TRB - EEEDirect recruitment of Assistant Professors in Government Engineering Colleges 2013 - 2014 & 2014 - 15 This material consists: Addentum Prospectus Syllabus Question paper for AP recruitment in Govt Engg Colleges 2012 Answer key for AP recruitment in Govt Engg Colleges 2012 Question paper for Lecturer recruitment in Govt Polytechnics Answer key for Lecturer recruitment in Govt Polytechnics Objective type questions and Answers for the following subjects o Control system o Electromagnetic theory o Electrical Engineering o Electrical Machine Design o Measurements and Instrumentation Prepared by V.Arivumani, Assistant Professor, Department of EEE, Government College of Engineering, Bargur - 635104. Mail Address:
[email protected] Web: www.co4.in Addendum for Notification/ Advertisement No. 03 / 2014 Dated : 16.07.2014 Government of Tamil Nadu TEACHERS RECRUITMENT BOARD 4th Floor, EVK Sampath Maaligai, DPI Compound, College Road, Chennai -600 006 The following Addendum is issued to the notification / advertisement No. 03/2014 relating to the Direct recruitment of Assistant Professors in Engineering Colleges, published in New Indian Express, Dinamani and the Daily Thanthi on 16.07.2014. ADDENDUM In the said advertisement under para 1, the important Dates may be read as follows: B. Commencement of Sale of Application : 17-08-2016 C. Last Date for Receipt of Application : 07-09-2016 D. Tentative Date of Written Examination : 22-10-2016 2. In light of the letter No.14730 /A2/2013 dated 19.06.2015 of Commissioner of Technical Education, Chennai, in the said advertisement under para 2, the subject-wise Details of Vacancies may be read as follows: BC MBC/ Sub. GT BC SC SC (A) ST Total Subject (M) DNC Code 14E G W G W G W G W G W G W G W G W All 01 Civil Engineering 5 2 4 2 1 4 1 3 1 1 18 6 24 02 Mechanical Engg. 6 2 3 1 1 4 1 2 1 1 16 6 22 03 E.E.E 4 2 3 2 1 2 1 2 1 1 13 6 19 04 E.C.E 5 2 3 2 1 4 1 2 1 1 15 7 22 05 EIE * 1 1 0 2 2 06 Computer Science Engg. 4 2 3 2 1 3 1 2 1 13 6 19 08 Metallurgy 1 1 0 1 09 Mathematics 5 2 5 2 1 3 2 3 2 17 8 25 10 English 3 2 4 2 1 3 1 2 1 13 6 19 11 Physics 3 2 4 2 1 3 2 3 1 14 7 21 12 Chemistry 3 2 3 2 1 2 1 3 1 12 6 18 TOTAL 38 18 32 18 6 3 28 1 23 9 5 1 132 60 192 1 Abbreviations : GT General Turn BC Backward Class BCM Backward Class Muslim MBC Most Backward Class DNC De-Notified Community SC Scheduled Caste ST Scheduled Tribe G General W Women SCA Scheduled Caste EEE Electrical and Electronics Engineering ECE Electronics and EIE Electronics and Instrumentation Engg. * Backlog Vacancies 1 3.In light of the letter No.339/I1/ 2016-1 dated 21.06.2016 of Higher Education (I1) Department, Chennai, the qualifications prescribed in GO(Ms)No.144, HE(B1)Dept., dated 15-06-2011 is to be followed for the direct recruitment of Assistant Professors in Non- Engineering subjects in Govt. Engineering Colleges. 4. In the said advertisement, under para 5, the age may be read as follows: Candidates should not be over 57 years of age, as on 01.07.2016 for Engineering and Non-engineering Subjects. (As p e r G.O M.S No.157 dated 15.09.2014 Higher Education Department). Important note: 1. The Candidates who have already applied in response to advertisement No.03/2014 dated 16.07.2014 and have no changes, need not apply again. However they should go through the prospectus available in the TRB website http://trb.tn.nic.in and note the new instructions therein. 2. The points regarding the equivalent subjects, age, key answers etc., are given in prospectus. 3. The original notification / advertisement No.03/2014 dated 16.07.2014, the corrigendum issued on 17.07.2014 and 09.09.2014 to the above said notification and the addendum with prospectus are available in TRB website http://trb.tn.nic.in 4. The New modified experience certificate model is attached in prospectus and available in TRB website. The candidates are requested to use the new modified experience certificate. 5. The candidates shall scrupulously follow the instructions comprised in the prospectus issued along with the application forms which also form part of this notification. MEMBER SECRETARY. 2 GOVERNMENT OF TAMIL NADU TEACHERS RECRUITMENT BOARD 4th Floor, EVK Sampath Maaligai, DPI Compound, College Road, Chennai 600 006. Direct recruitment of Assistant Professors in Government Engineering Colleges 2013 - 2014 & 2014 - 15 PROSPECTUS 1. Applications are invited from qualified candidates up to 5.00 p.m on 07-09-2016 for written competitive examination for direct recruitment of Assistant Professors in Government Engineering Colleges. The posts will be filled up on the basis of marks secured in written competitive examination and weightage marks awarded after Certificate Verification, following communal reservation as per existing rules of the Government of Tamilnadu. 2. The tentative estimated vacancies for the post of Assistant Professors in Government Engineering Colleges are given in Annexure - I. (The vacancies are likely to be changed). 3. Scale of Pay : Rs.15,600 - 39,100/- + AGP. Rs.6000 /- 4. Communal Reservation : 69% Communal Reservation will be strictly followed as per the existing rules and Government Orders in vogue. 1 5. Tamil Medium Reservation : 20% reservation on preferential basis for persons studied in Tamil Medium (PSTM) is followed as per existing Government Orders. This reservation is subject to the availability of suitable eligible candidates. In the event of non-availability of such candidates the posts reserved for PSTM candidates will be filled by General candidates. 6. Special Reservation: 3% Reservation for the Differently Abled candidates (PWD candidates) will be followed as per existing Government Orders. a) Visually Impaired: Candidates should possess certificate in prescribed format from the Competent Authority for one of the following: (i) Total absence of sight on both eyes, or (ii) Visual acuity not exceeding 6/60 or 20/200 (Snellen) in the better eye with correcting lenses or (iii) Limitation of the field of vision subtending an angle of 20 degrees or worse. One-eyed visually impaired persons cannot claim reservation against Visually Impaired category. b) Orthopedically Impaired: Candidates claiming reservation under the Differently-Abled (Ortho) category should possess certificate in prescribed format from the Competent Authority for at least 40% and above. Note: All certificates should have been obtained prior to the last date for submission of filled-in Application announced in the Recruitment Notification published in Newspapers. 2 7.Qualifications: Post Qualification Assistant Professor B.E. or B.Tech and M.E. or M.Tech. in (Engineering Subjects) the relevant Branch of Engineering or [Civil, Mechanical, EEE, Technology with First Class or its ECE, EIE, Computer equivalent either in B.E or B.Tech. / Science Engineering, and M.E. or M.Tech Metallurgy] Assistant Professor 1. Master’s Degree in the relevant (Non-Engineering subject with good academic record Subjects) with not less than 55% of marks or [English / Mathematics an equivalent Cumulative Grade Point / Physics / Chemistry] Average (CGPA) from an Indian University or an equivalent Degree from a Foreign University, and 2. Pass in the National Eligibility Test (NET) for Lecturers conducted by the UGC, Council for Scientific and Industrial Research (CSIR) or similar test accredited by the University Grants Commission. Provided that holders of Ph.D Degree are exempted from passing the said test. 3 Equivalent Subjects : Candidates should apply for the relevant subject. If a candidate claims that the educational qualification in the subject possessed by him/her is equivalent to any one of the above mentioned subjects, the appointing authority i.e., user department (Directorate of Technical Education) will decide the equivalence at the time of appointment. The acceptance or rejection of such claims is vested with Directorate of Technical Education. Candidate may apply only for the subjects for which the vacancies are notified and subject code numbers assigned. The candidates applying for the posts mentioned in Annexure I should have passed Tamil Language under Part I or Part II in SSLC / PUC / Higher Secondary Course level. If not, he / she should pass Tamil Language Test conducted by the Tamil Nadu Public Service Commission within two years from the date of their appointment. 8. Community Certificate : Permanent Community Certificate obtained from the under-mentioned authorities on or before the last date for submission of the filled-in application form is essential for candidates claiming communal reservation. a. ST - Revenue Divisional Officer / Sub-collector dated after 11.11.1989. b. SC - Tahsildar of native taluk of the candidate. c. BC / MBC / DNC - Headquarters’ Deputy Tahsildar or Special Deputy Tahsildar of the candidate’s native taluk. 4 Note: (i) Candidates with the Community Certificate issued by other authorities from Tamil Nadu will not be considered for communal reservation. (ii) Married Women should possess Community certificate issued in father’s name only. (iii) The other State candidates (other than Tamil Nadu) claiming Community Reservation will be considered only for General Turn (GT). 9. Age: Candidates should not be over 57 years of age, as on 01.07.2016. (As per G.O M.S No.157 dated 15.09.2014 Higher Education Department) 10. Application form and Examination fee: a. The OMR Application Form along with Prospectus can be purchased from 17-08-2016 to 07-09-2016 in person from the Office of the Chief Educational Officers of all 32 Districts in Tamilnadu on payment of Rs.100/- (Rupees One hundred only) in cash towards the cost of the Application Form and Prospectus. b. Submission of Filled-in Application Forms: Candidates are advised to submit the filled-in application forms at the Office of the Chief Educational Officer concerned on or before 07-09-2016 upto 5.00 P.M. The Candidates are advised NOT to send the filled-in Application Forms by post or in person to the Teachers Recruitment Board, Chennai – 600 006. 5 c. Candidates are advised to get an acknowledgement on the photocopy of the Application Form in the following format. Acknowledgement Format: TEAM No : Sl. No of Receipt : Date of Receipt : Signature of the : Team Head O/o Chief Educational Officer ..........……………………………… d. Applications received in any form other than the OMR application issued by Teachers Recruitment Board shall be rejected. e. Examination Fee: The Examination fee is Rs.600/- (Rupees Six Hundred only) for all the candidates except SC/ST and Differently Abled candidates. For SC/ST and Differently Abled candidates examination fee is Rs.300/- (Rupees Three Hundred only). The fee should be paid by the candidates in any Branch of S T A T E B A N K O F I N D I A / INDIAN OVERSEAS BANK using only the prescribed challan attached with the prospectus. Payment of examination fees in any other method will not be accepted. The prescribed challan contains certain details of the fees, Application number, account number for the specific recruitment etc., Candidates have to write the Name of the Bank where the candidates 6 make the payment, the date of payment, fee remittance branch code and bank journal number in the relevant columns in the application form. f. The Teachers Recruitment Board's copy of the challan should not be pasted / stapled/ tied, but it has to be kept in a separate envelope and submitted along with the application form without fail. g. The decision of the Teachers Recruitment Board is final for fixing the eligibility of the candidate to appear for the Examination. 11. Scheme of Examination: The written examination will consist of a single paper of 3-hour duration with 190 marks. The question paper will be of objective type with multiple choice questions. The question paper will be based on the Syllabus for the subject hosted on TRB website. The marks allotted to the Main Subject and General Knowledge are as follows Main Part A 1 mark question: 100 100 Marks Subject Part B 2 mark question: 40 80 Marks General Knowledge 1 mark question: 10 10 Marks Total questions : 150 190 Marks The Question Papers for all subjects will be in English only. The candidates are required to answer the questions in the special OMR answer sheet provided, by shading a single answer for each question in blue or black ball-point pen only. The decision of the Chairman, Teachers Recruitment Board is final for fixing the eligibility of the candidate to sit for the Examination. 7 12.Written Examination: The written Examination will be held on 22-10-2016 from 10.00 A.M. to 1.00 P.M. The venue for the Examination will be intimated in the Hall Ticket. Hall Ticket will be uploaded in Teachers Recruitment Board official website http://www.trb.tn.nic.in. The Hall Tickets will not be sent through post at any cost. The candidate may refer to TRB website (http://trb.tn.nic.in) for details. The candidate will be allowed to sit for examination after verifying his/her identity with the nominal roll in Exam centre before the commencement of the examination. Visually Impaired candidates will be allowed assistance of Scribes, who are not Graduates/Postgraduates in the respective Subjects. The decision of Chairman, Teachers Recruitment Board on the eligibility of the candidate to sit for the Examination will be final. Key Answers: Tentative key will be published on completion of the exams. The candidates who intend to have objections on tentative key answers shall raise them along with materials they relay within 5 days from date of release of tentative key. Any objections and materials produced beyond the stipulated time will not be entertained and that candidates are stopped from questioning them at later point of time. On consideration of such objections, final key answers would be published and the same would be final. No independent orders either accepting or rejecting the objections of the candidates will be passed. Only final key would be published. 8 Constitution of experts to consider the objections cannot be questioned by the candidates. Written E xamination Results : The results of the Written Competitive Examination with Marks of all the candidates will be released in the website of Teachers Recruitment Board viz. http://trb.tn.nic.in by notifying about release of results in the Press / Media. 13. Merit List : The merit list of candidates short-listed for Certificate Verification (CV), in the ratio of 1:2, based on written examination marks following the communal reservation, will also be published in the website. If more than one candidate secures the same lowest cut- off mark for a particular communal turn, all such candidates will be called for Certificate Verification. Hence the number of candidates called for Certificate Verification may be slightly higher than twice the number of vacancies. Weightage marks will not be added to the marks scored by the candidate in the written examination for short listing candidates for certificate verification. 14. Certificate Verification : Candidates, short-listed as above will be called for certificate verification by intimation through official website. The candidate should bring the original and attested copies of all certificates to the certificate verification centre, as stated in the call letter for Certificate Verification. Weightage marks as shown below will be awarded after Certificate Verification. All the certificates should have been issued prior to the last date for submission of filled 9 in Application (cut-off date). Certificate issued after the cut off date will not be considered and shall be rejected. Description Engineering Non-Engineering For Teaching experience i of two years and above 2 marks 2 marks in a recognized college For M.Phil Degree from a recognized University ii in the appropriate --- 3 marks branch of study in the non-engineering subject For Ph.D. in the relevant 8 marks 5 marks iii subject These marks will be added for preparing the provisional merit-cum- communal selection list. Teaching Experience Certificate, issued by Principal of the Institution in the prescribed form (Specimen copy of the Teaching Experience Certificate is attached in Annexure-II) and countersigned by the officer concerned, should be produced. The Teaching Experience Certificate may be obtained for a period of service after the cut-off date, but the period of service shall be counted upto the cut-off date only. The certificates for higher qualifications, shown above, should have been obtained before the cut-off date. 10 15. Provisional Selection : The provisional list of candidates selected for appointment after the Certificate Verification and addition of weightage marks for the short-listed candidates duly following the merit cum communal rotation, will be published in the website of TRB viz. http://trb.tn.nic.in by notifying about release of the provisional result in the Press/media. Intimation to the provisionally selected candidates will not be sent by post individually. The final eligibility of the candidates will be subject to the decision of Teachers Recruitment Board and the Board has every right to alter or cancel their results. 16. TA / DA : No T.A./D.A. will be paid. Candidates will have to bear their own expenses to attend the Written Examination in districts and for Certificate Verification at Teachers Recruitment Board, Chennai, if called. 17. Special Instructions: a. The Application Forms should be carefully filled up. The passport size photograph should be pasted in the space provided and should not be stapled. The photograph should not be attested and it should be free from any mark, as the same has to be used for printing the Hall Tickets. b. Incomplete Application Forms will be summarily rejected. Canvassing in any form will be a disqualification for selection. c. The Application Form should not be folded. The Application form should be submitted in the envelope issued along with the form. 11 d. The Subject Code should be clearly filled up in the space allotted in the Application Form. The name of the subject should be entered exactly as shown in the application form. e. As the form is computer readable and pre-programmed, any information written outside the boxes provided will not be read by the computer. Hence, altering the form or adding any additional box will result in your application becoming invalid. f. A photocopy of the filled and signed application form with acknowledgement may be preserved. g. The TRB will not take any responsibility for non-submission of essential certificates by the candidates. h. The Teaching Experience Certificate should be in the prescribed format as in the Annexure II. i. Candidates are informed to ascertain their full eligibility for the post to which they have applied. The onus of proof of providing subject equivalence is vested with the candidates only. TRB cannot take any responsibility for the non-selection and ineligibility if any mistake detected at any stage during or after the recruitment and declaration of results and their candidature will be liable for cancellation. j. Electronic gadgets / Clark’s Table / Calculators / Cell Phones are not permitted inside the Examination Hall. 12 k. In the matter of recruitment, the decision of the TRB is final. Any representation for non-selection will not be entertained at any cost. Application forms will not be accepted after 5.00 p.m. on 07-09-2016. MEMBER SECRETARY. 13 14 15 INSTRUCTIONS TO FILL UP THE OMR APPLICATION FORM FOR DIRECT RECRUITMENT OF ASSISTANT PROFESSORS IN ENGINEERING COLLEGES 2013-2014 and 2014-2015 General: A. Candidates are advised to be very careful while filling in the OMR Application. Omission to fill in the relevant columns and / or shade them and commission of mistakes in writing / marking / shading the required details in the OMR Application will result in rejection of the OMR Application. B. Candidates should use prescribed OMR Application form for Recruitment Examination for Assistant Professors in Govt. Engineering Colleges. C. Application forms should be filled up in Blue / Black ball point pen only. D. After filling up of application take xerox copy of the same and use it for getting acknowledgment from the Office of the Chief Educational officer concerned. **** 16 1. CANDIDATE’S NAME: Candidates should write their name in capital Letters, each letter occupying one box. The initials must be written at the end after leaving one box blank after the name. Moreover the candidates have to correctly shade the appropriate circles below each letter as the computer reads the shaded region only. For Example : If the Candidate’s name is P. UMA MAHESHWARI, fill in the box as below. U M A M A H E S H W A R I P 2. DATE OF BIRTH: Fill-in the appropriate boxes with Date of Birth (e.g. 12 JAN 1982) and shade the relevant circles. 3. NAME OF THE FATHER / MOTHER / HUSBAND / GUARDIAN: a. Shade the relevant circle b. Candidate should write his/her father’s / mother’s / husband’s /guardian’s name in capital letters. Each letter should occupy one box. 4. GENDER: Candidates should shade the appropriate circle whether MALE or FEMALE or TRANSGENDER. 5. COMMUNITY: Candidate should shade the relevant circle to denote his/her community. 6. SPECIFY DIFFERENTLY ABLED (IF ANY) : If the Candidate is differently-abled with Physical Disability / Visual impairment, he/she should shade the appropriate circle. Otherwise no need to shade the circle. 17 7. Post Applied For : Candidate should shade the relevant circle to denote the post applied for. 8. Subject Code : Fill in the Box with correct subject code and shade the relevant circle. For subject code refer Annexure I. 9. Exam Center Code : Candidate should select the Examination Centre from the list given in Annexure III and fill up the boxes with the selected centre number and shade the appropriate circles. 10. Photograph : Candidates should paste the recent Passport size photo. (Don’t staple the photo with pin). Applications with stapled photo will not be accepted 11. Signature of the Candidate : Put the signature within the box 12. Address for Communication : Write the Name and Address in capital letters and PIN code legibly in the space provided for that purpose. As this portion is to be scanned and uploaded as Hall Ticket, strictly limit your writings within the boxes provided in the application form 13. (a) Educational Qualification : Shade the relevant circle to denote the subject studied in UG and PG Degree. (b)whether secured 60% and above (B.E/B.Tech and M.E/M.Tech): Shade the relevant circle whether secured 55% and above (M.A/M.Sc) : Shade the relevant circle (c) Medium Studied in .............. : Shade the relevant circle 18 (d) Have you completed SLET / NET (OR) Ph.D, M.Phil : Shade the relevant circle 14. PAYMENT DETAILS: The Payment Details have to be made by making entries in boxes and shading the circles. Examination Fees paid: The Examination fee is Rs.600/- for all the candidates except SC/ST and Differently Abled candidates. For SC/ST and Differently Abled candidates examination fees is Rs.300/- Bank : Payment of Examination Fees may be made in any one of the following Banks - State Bank of India (SBI) or Indian Overseas Bank (IOB). Shade the appropriate circle. Date of payment: - Please enter the date of payment as mentioned in the Challan by which payment is made in the Bank. Remittance Branch Code: Candidate has to write 5 digit branch code in the column provided. If your Branch Code is in 4 digits, put ‘0’ in first box and write the remaining 4 digits. Bank Journal No.: 9 digit numeric. This number will be given by the remittance bank during the payment of fees through the challan issued along with the application form. If the Journal Number is 8 digits add ‘0’ in the first box and if the Journal Number is 7 digits add ‘0’ in the first two boxes and write the other digits in the remaining boxes, so that the Bank Journal Number will be 9 digits. 19 For Example: If the Journal Number is 54376421 write in the box provided and shade the relevant circles. 0 0 0 5 4 3 7 6 4 2 1 If the Journal Number is 1453247 write in the box provided and shade the relevant circles. 0 0 0 0 1 4 5 3 2 4 7 15. DECLARATION: The Declaration given in the second page must be signed without fail. Sign in the box provided. Applications without signature of the candidate will be summarily rejected by Teachers Recruitment Board. 20 ANNEXURE – I Estimated Vacancies [Tentative] 2013-2014 Sub. GT BC BC (M) MBC/ DNC SC SC (A) ST Total No S. Code Subject G W G W G W G W G W G W G W G W All Civil 1 14E01 5 2 4 2 1 4 1 3 1 1 18 6 24 Engineering Mechanical 2 14E02 6 2 3 1 1 4 1 2 1 1 16 6 22 Engg. 3 14E03 E.E.E 4 2 3 2 1 2 1 2 1 1 13 6 19 4 14E04 E.C.E 5 2 3 2 1 4 1 2 1 1 15 7 22 5 14E05 EIE * 1 1 0 2 2 Computer 6 14E06 4 2 3 2 1 3 1 2 1 13 6 19 Science Engg. 7 14E08 Metallurgy 1 1 0 1 8 14E09 Mathematics 5 2 5 2 1 3 2 3 2 17 8 25 9 14E10 English 3 2 4 2 1 3 1 2 1 13 6 19 10 14E11 Physics 3 2 4 2 1 3 2 3 1 14 7 21 11 14E12 Chemistry 3 2 3 2 1 2 1 3 1 12 6 18 TOTAL 38 18 32 18 6 3 28 11 23 9 5 1 132 60 192 * Backlog vacancies Note: The estimated number of vacancies given above is tentative and subject to modification from time to time. 21 For Submission to Teachers Recruitment Board, Chennai -6 Passport size - photograph of the Candidate duly Annexure-II attested by the certificate issuing EXPERIENCE CERTIFICATE authority. (Sign and Seal should be partly in photograph and application) Name of the Candidate Name and address of the Institution in which employed Type of Institution Govt. / Aided / Self-Financing / State University / Deemed University Date of appointment as (a) Lecturer (b) Senior Lecturer (c) Assistant Professor Subjects taught No. of Total period of service S.No Subjects taught periods per Date Date Period week from to Y M D i ii TOTAL Certified that the above facts are verified with Pay acquittance / Staff attendance register / Appointment & Termination letter and other relevant records available on behalf of the above individual and found correct. Place: Signature: Date: Name: Seal: Designation: Principal (In case of Govt. Colleges/University/Aided & Self Finance Colleges) Counter Signature Ref. No. Place: Signature: Date: Name: Seal: Designation: / (In Director, DOTE Regional Joint Director (In case of Govt/Aided/ Self-finance case of Govt/Aided/Self-finance Engineering Colleges) Arts & Registrar Science Collges) (In case of State/ Deemed Universities) 22 Note: Separate form should be used for each Institution worked. The Teaching Experience Certificate should be properly attested, signed and proper seal affixed by the Regional Joint Director of Collegiate Education in the case of Government / Aided/ Self-Financing Arts & Science Colleges and Director of Technical Education in the case of Engineering Colleges / Registrars in case of Deemed Universities. Teaching Experience Certificate in the subject applied alone will be considered. Inconsistencies/errors that are not attested by the issuing officer with seal will result in rejection of the certificate. The issuing authorities should maintain records including serial no, date of issue, place of issue and keep one original copy of the certificates issued by them for future verification. A passport size photograph should be affixed in each certificate. Those photographs have to be attested by the issuing Authority. Part of the signature and seal should be on the photograph. Marks will be awared only when the candidate submit the Experience Certificate at the timem of certificate verification. 23 Annexure III Exam Center and Code District Exam Center Code Chennai 01 Vellore 02 Villupuram 03 Salem 04 Coimbatore 05 Trichy 06 Thanjavur 07 Madurai 08 Tirunelveli 09 Sivagangai 10 24 SYLLABUS FOR COMPETITIVE EXAMINATION FOR RECRUITMENT OF ASSISTANT PROFESSORS IN GOVERNMENT ENGINEERING COLLEGES 2013-2014 ELECTRICAL AND ELECTRONICS ENGINEERING Unit 1: Engineering Mathematics Linear Algebra: Matrix Algebra, Systems of Linear equations, Eigen Values and eigen vectors. Calculus: Mean Value Theorems, Theorems of integral Calculus Evaluation of definite and improper integrals, Partial Derivatives, Maxima and minima, Multiple integrals, Fourier series. Vector identities, Directional derivatives, Line, Surface and Volume integrals, Stokes, Gauss and Green’s theorems. Differential equations: First order equation (linear and nonlinear), Higher order linear differential equations with constant coefficients, Method of variation of parameters, Cauchy’s and Euler’s equations, initial and boundary value problems, Partial Differential Equations and variable separable method. Complex variables: Analytic functions, Cauchy’s integral theorem and integral formula, Taylor’s and Laurent’ series, Residue theorem, solution integrals. Probability and Statistics: Sampling theorems, Conditional probability, Mean, median, mode and standard deviation, Random variables, Discrete and continuous distributions, Poisson, Normal and Binomial distribution, Correlation and regression analysis. Numerical Methods: Solutions of non-linear algebraic equations, single and multi-step methods for differential equations. Transform Theory: Fourier transform, Laplace transform, Z-transform. Unit 2: Electric Circuits and Fields Network graph, KCL, KVL, node and mesh analysis, transient response of dc and ac networks; sinusoidal steady-state analysis, resonance, basic filter concepts; ideal current and voltage sources, Thevenin’s, Norton’s and Superposition and Maximum Power Transfer theorems, two-port networks, three phase circuits. Gauss Theorem, electric field and potential due to point, line, plane and spherical charge distributions; Ampere’s and Biot-Savart’s laws; inductance; dielectrics; capacitance. TEACHERS RECRUITMENT BOARD, CHENNAI 600 006 Page 7 SYLLABUS FOR COMPETITIVE EXAMINATION FOR RECRUITMENT OF ASSISTANT PROFESSORS IN GOVERNMENT ENGINEERING COLLEGES 2013-2014 Unit 3: Signals and Systems Representation of continuous and discrete-time signals; shifting and scaling operations; linear, time-invariant and casual systems; Fourier series representation of continuous periodic signals; sampling theorem; Fourier, Laplace and Z transforms. Unit 4: Electrical Machines Single Phase transformer – equivalent circuit, phasor diagram, tests, regulation and efficiency; three phase transformers – connections, parallel operation; auto-transformer; energy conversion principles; DC machines – types, windings, generator characteristics, armature reaction and commutation, starting and speed control of motors; three phase induction motors – principles, types, performance characteristics, starting and speed control; Single phase induction motors; synchronous machines – performance, regulation and parallel operation of generators, motor starting, characteristics and applications; servo and stepper motors. Unit 5: Power Systems Basic power generation concepts; transmission line models and performance; cable performance insulation; corona and radio interference; distribution systems; per-unit quantities; bus impedance and admittance matrices; load flow; voltage control; power factor correction; economic operation; symmetrical components; fault analysis. Unit 6: Protection and switchgear Principles of over-current, differential and distance protection; solid state relays and digital protection; circuit breakers; system stability concepts, swing curves and equal area criterion; HVDC transmission and FACTS concepts. Unit 7: Control Systems Principles of feedback; transfer function; block diagrams; steady – state errors; Routh and Niquist techniques; Bode plots; root loci; lag, lead and lead-leg compensation; state space model; state transition matrix, controllability and observability. Unit 8: Electrical and Electronic Measurements Bridges and potentiometers; PMMC, moving iron, dynamometer and induction type instruments; measurement of voltage, current, power, energy and power factor; instrument transformers; digital voltmeters and multimeters; phase, time and frequency measurement; Q-meters; Oscilloscopes; potentiometric recorders; error analysis. TEACHERS RECRUITMENT BOARD, CHENNAI 600 006 Page 8 SYLLABUS FOR COMPETITIVE EXAMINATION FOR RECRUITMENT OF ASSISTANT PROFESSORS IN GOVERNMENT ENGINEERING COLLEGES 2013-2014 Unit 9: Analog and Digital Electronics Characteristics of diodes, BJT, FET; amplifiers – biasing, equivalent circuit and frequency response; oscillators and feedback amplifiers; operational amplifiers – characteristics and applications; simple active filters; VCOs’ and timers; combinational and sequential logic circuits; multiplexer; Schmitt trigger; multi-vibrators; sample and hold circuits; A/D and D/A convertors; 8-bit microprocessor basics, architecture, programming and interfacing. Unit 10: Power Electronics and Drives Semiconductor power diodes, transistors, thyristors, triacs, GTOs, MOSFETs and IGBTs – static characteristics and principles of operation; triggering circuits; phase control rectifiers; bridge converters – fully controlled and half controlled; principles of choppers and inverters; basis concepts of adjustable speed dc and ac drives. TEACHERS RECRUITMENT BOARD, CHENNAI 600 006 Page 9 KEY-EG03 TEACHERS RECRUITMENT BOARD, CHENNAI-6. EG03 (EEE) ====================================================================== 1 2 3 4 5 6 7 8 9 10 A B A D D B D B B A 11 12 13 14 15 16 17 18 19 20 A B C D A C C D C B 21 22 23 24 25 26 27 28 29 30 B A B C D D C C C B 31 32 33 34 35 36 37 38 39 40 B * C B A D C C A D 41 42 43 44 45 46 47 48 49 50 B A D C B A C C B B 51 52 53 54 55 56 57 58 59 60 B D D B C D D C C C 61 62 63 64 65 66 67 68 69 70 D B A C B A D B D A 71 72 73 74 75 76 77 78 79 80 B A B A D C A B B B 81 82 83 84 85 86 87 88 89 90 C A D C D C A C C B 91 92 93 94 95 96 97 98 99 100 A C B A D D D D D D 101 102 103 104 105 106 107 108 109 110 D D B B C C C C D B 111 112 113 114 115 116 117 118 119 120 D C A B C A C C B C 121 122 123 124 125 126 127 128 129 130 C D A B A C B A A C 131 132 133 134 135 136 137 138 139 140 C C C C C C C B D A 141 142 143 144 145 146 147 148 149 150 C A C D C B B B D C ====================================================================== Checked By 1. Checked By 2. Page 1 K-PT03A TEACHERS RECRUITMENT BOARD, CHENNAI-6. (12PT03-EEE) BOOK A ====================================================================== 1 2 3 4 5 6 7 8 9 10 B C C D C B A B C * 11 12 13 14 15 16 17 18 19 20 C C B A D B D B A B 21 22 23 24 25 26 27 28 29 30 A B D C A D C * D A 31 32 33 34 35 36 37 38 39 40 C B A C/D A C D D D B 41 42 43 44 45 46 47 48 49 50 * B C A C * C B B C 51 52 53 54 55 56 57 58 59 60 A B B B A B D C B C 61 62 63 64 65 66 67 68 69 70 C B C A C A D B * C 71 72 73 74 75 76 77 78 79 80 B B C A A D B B C A 81 82 83 84 85 86 87 88 89 90 C * C A B A D B C A 91 92 93 94 95 96 97 98 99 100 C B B D B B D D B A 101 102 103 104 105 106 107 108 109 110 A C B C C B D B C B 111 112 113 114 115 116 117 118 119 120 B D B C * B A A * D 121 122 123 124 125 126 127 128 129 130 B B A D B C C B A C 131 132 133 134 135 136 137 138 139 140 A * A B A A A B A B 141 142 143 144 145 146 147 148 149 150 D D C B C D B B A * ====================================================================== Checked By 1. Checked By 2. Page 1 K-PT03B TEACHERS RECRUITMENT BOARD, CHENNAI-6. (12PT03-EEE) BOOK B ====================================================================== 1 2 3 4 5 6 7 8 9 10 C C B A D B D B A B 11 12 13 14 15 16 17 18 19 20 A B B B A B D C B C 21 22 23 24 25 26 27 28 29 30 B C C D C B A B C * 31 32 33 34 35 36 37 38 39 40 * B C A C * C B B C 41 42 43 44 45 46 47 48 49 50 C B C A C A D B * C 51 52 53 54 55 56 57 58 59 60 C B B D B B D D B A 61 62 63 64 65 66 67 68 69 70 B B C A A D B B C A 71 72 73 74 75 76 77 78 79 80 C * C A B A D B C A 81 82 83 84 85 86 87 88 89 90 C B A C/D A C D D D B 91 92 93 94 95 96 97 98 99 100 A B D C A D C * D A 101 102 103 104 105 106 107 108 109 110 C B D B C B B C A C 111 112 113 114 115 116 117 118 119 120 A * A B A A A B A B 121 122 123 124 125 126 127 128 129 130 D D C B C D B B A * 131 132 133 134 135 136 137 138 139 140 B D B C * B A A * D 141 142 143 144 145 146 147 148 149 150 B B A D B C C B A C ====================================================================== Checked By 1. Checked By 2. Page 1 K-PT03C TEACHERS RECRUITMENT BOARD, CHENNAI-6. (12PT03-EEE) BOOK C ====================================================================== 1 2 3 4 5 6 7 8 9 10 * B C A C * C B B C 11 12 13 14 15 16 17 18 19 20 C B B D B B D D B A 21 22 23 24 25 26 27 28 29 30 C B A C/D A C D D D B 31 32 33 34 35 36 37 38 39 40 C * C A B A D B C A 41 42 43 44 45 46 47 48 49 50 A B D C A D C * D A 51 52 53 54 55 56 57 58 59 60 B B C A A D B B C A 61 62 63 64 65 66 67 68 69 70 C C B A D B D B A B 71 72 73 74 75 76 77 78 79 80 C B C A C A D B * C 81 82 83 84 85 86 87 88 89 90 B C C D C B A B C * 91 92 93 94 95 96 97 98 99 100 A B B B A B D C B C 101 102 103 104 105 106 107 108 109 110 D B A C B C C B C B 111 112 113 114 115 116 117 118 119 120 C C B A C D B B A * 121 122 123 124 125 126 127 128 129 130 A * A B A B D B C * 131 132 133 134 135 136 137 138 139 140 B B A D B D D C B C 141 142 143 144 145 146 147 148 149 150 A A B A B B A A * D ====================================================================== Checked By 1. Checked By 2. Page 1 K-PT03D TEACHERS RECRUITMENT BOARD, CHENNAI-6. (12PT03-EEE) BOOK D ====================================================================== 1 2 3 4 5 6 7 8 9 10 C B B D B B D D B A 11 12 13 14 15 16 17 18 19 20 C * C A B A D B C A 21 22 23 24 25 26 27 28 29 30 B B C A A D B B C A 31 32 33 34 35 36 37 38 39 40 C B C A C A D B * C 41 42 43 44 45 46 47 48 49 50 A B B B A B D C B C 51 52 53 54 55 56 57 58 59 60 * B C A C * C B B C 61 62 63 64 65 66 67 68 69 70 C B A C/D A C D D D B 71 72 73 74 75 76 77 78 79 80 A B D C A D C * D A 81 82 83 84 85 86 87 88 89 90 C C B A D B D B A B 91 92 93 94 95 96 97 98 99 100 B C C D C B A B C * 101 102 103 104 105 106 107 108 109 110 C B C B D B A C B C 111 112 113 114 115 116 117 118 119 120 D D C B C A * A B A 121 122 123 124 125 126 127 128 129 130 B D B C * B B A D B 131 132 133 134 135 136 137 138 139 140 B A A * D D B B A * 141 142 143 144 145 146 147 148 149 150 C C B A C A A B A B ====================================================================== Checked By 1. Checked By 2. Page 1 GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS NO OF UNIT NAME QNS 1A DC GENERATORS 124 1B DC MOTORS 123 2 TRANSFORMERS 135 THREE PHASE INDUCTION 3A MOTORS 101 SINGLE PHASE INDUCTION 3B MOTORS 110 4 SYNCHRONOUS MOTORS 124 TRANSMISSION AND 5A DISTRIBUTION 102 5B CABLES 56 TOTAL 875 1. A. DC GENERATORS 1. Laminations of core are generally made of (a) case iron (b) carbon (c) silicon steel (d) stainless steel Ans: c 2. Which of the following could be lamina-proximately the thickness of laminations of a D.C. machine ? (a) 0.005 mm (b) 0.05 mm (c) 0.5 m (d) 5 m Ans: c 3. The armature of D.C. generator is laminated to (a) reduce the bulk (b) provide the bulk (c) insulate the core (d) reduce eddy current loss Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: d 4. The resistance of armature winding depends on (a) length of conductor (b) cross-sectional area of the conductor (c) number of conductors (d) all of the above Ans: d 5. The field coils of D.C. generator are usually made of (a) mica (b) copper (c) cast iron (d) carbon Ans: b 6. The commutator segments are connected to the armature conductors by means of (a) copper lugs (b) resistance wires (c) insulation pads (d) brazing Ans: a 7. In a commutator (a) copper is harder than mica (b) mica and copper are equally hard (c) mica is harder than copper (d) none of the above Ans: c 8. In D.C. generators the pole shoes are fastened to the pole core by (a) rivets (b) counter sunk screws (c) brazing (d) welding Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 9. According to Fleming's right-hand rule for finding the direction of induced e.m.f., when middle finger points in the direction of induced e.m.f., forefinger will point in the direction of (a) motion of conductor (b) lines of force (c) either of the above (d) none of the above Ans: b 10. Fleming's right-hand rule regarding direction of induced e.m.f., correlates (a) magnetic flux, direction of current flow and resultant force (b) magnetic flux, direction of motion and the direction of e.m.f. induced (c) magnetic field strength, induced voltage and current (d) magnetic flux, direction of force and direction of motion of conductor Ans: b 11. While applying Fleming's right-hand rule to And the direction of induced e.m.f., the thumb points towards (a) direction of induced e.m.f. (b) direction of flux (c) direction of motion of the conductor if forefinger points in the direction of generated e.m.f. (d) direction of motion of conductor, if forefinger points along the lines of flux Ans: d 12. The bearings used to support the rotor shafts are generally (a) ball bearings (b) bush bearings (c) magnetic bearmgs (d) needle bearings Ans: a 13. In D.C. generators, the cause of rapid brush wear may be (a) severe sparking (b) rough commutator surface (c) imperfect contact (d) any of the above Ans: d Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 14. In lap winding, the number of brushes is always (a) double the number of poles (b) same as the number of poles (c) half the number of poles (d) two Ans: b 15. For a D.C. generator when the number of poles and the number of armature conductors is fixed, then which winding will give the higher e.m.f. ? (a) Lap winding (b) Wave winding (c) Either of (a) and (b) above (d) Depends on other features of design Ans: b 16. In a four-pole D.C. machine (a) all the four poles are north poles (b) alternate poles are north and south (c) all the four poles are south poles (d) two north poles follow two south poles Ans: b 17. Copper brushes in D.C. machine are used (a) where low voltage and high currents are involved (b) where high voltage and small cur-rents are involved (c) in both of the above cases (d) in none of the above cases Ans: a 18. A separately excited generator as compared to a self-excited generator (a) is amenable to better voltage con-trol (b) is more stable (c) has exciting current independent of load current (d) has all above features Ans: d 19. In case of D.C. machines, mechanical losses are primary function of (a) current Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) voltage (c) speed (d) none of above Ans: c 20. Iron losses in a D.C. machine are independent of variations in (a) speed (b) load (c) voltage (d) speed and voltage Ans: b 21. In D.C. generators, current to the external circuit from armature is given through (a) commutator (b) solid connection (c) slip rings (d) none of above Ans: a 23. Brushes of D.C. machines are made of (a) carbon (b) soft copper (c) hard copper (d) all of above Ans: a 24. If B is the flux density, I the length of conductor and v the velocity of conductor, then induced e.m.f. is given by (a)Blv (b)Blv2 (c)Bl2v (d)Bl2v2 Ans: a 25. In case of a 4-pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be (a) 4 (b) 8 (c) 16 (d) 32 Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 26. The material for commutator brushes is generally (a) mica (b) copper (c) cast iron (d) carbon Ans: d 27. The insulating material used between the commutator segments is normally (a) graphite (b) paper (c) mica (d) insulating varnish Ans: c 28. In D.C. generators, the brushes on commutator remain in contact with conductors which (a) lie under south pole (b) lie under north pole (c) lie under interpolar region (d) are farthest from the poles Ans: c 29. If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis, there will be (a) demagnetisation only (b) cross magnetisation as well as magnetisation (c) crossmagnetisation as well as demagnetising (d) cross magnetisation only Ans: c 30. Armature reaction of an unsaturated D.C. machine is (a) crossmagnetising (b) demagnetising (c) magnetising (d) none of above Ans: a 31. D.C. generators are connected to the busbars or disconnected from them only under the floating condition (a) to avoid sudden loading of the primemover (b) to avoid mechanicaljerk to the shaft (c) to avoid burning of switch contacts Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) all above Ans: d 32. Eddy currents are induced in the pole shoes of a D.C. machine due to (a) oscillating magnetic field (b) pulsating magnetic flux (c) relative rotation between field and armature (d) all above Ans: c 33. In a D.C. machine, short-circuited field coil will result in (a) odour of barning insulation (b) unbalanced magnetic pull producing vibrations (c) reduction of generated voltage for which excitation has to be increased to maintain the voltage (d) all above Ans: 34. Equilizer rings are required in case armature is (a) wave wound (b) lap wound (c) delta wound (d) duplex wound Ans: b 35. Welding generator will have (a) lap winding (b) wave winding (c) delta winding (d) duplex wave winding Ans: a 36. In case of D.C. machine winding, number of commutator segments is equal to (a) number of armature coils (b) number of armature coil sides (c) number of armature conductors (d) number of armature turns Ans: a 37. For a D.C. machines laboratory following type of D.C. supply will be suitable (a) rotary converter (b) mercury are rectifier (c) induction motor D.C. generator set Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) synchronous motor D.C. generator set Ans: c 38. The function of pole shoes in the case of D.C. machine is (a) to reduce the reluctance of the magnetic path (b) to spread out the flux to achieve uniform flux density (c) to support the field coil (d) to discharge all the above functions Ans: d 39. In the case of lap winding resultant pitch is (a) multiplication of front and back pitches (b) division of front pitch by back pitch (c) sum of front and back pitches (d) difference of front and back pitches Ans: d 40. A D.C. welding generator has (a) lap winding (b) wave moving (c) duplex winding (d) any of the above Ans: a 41. Which of the following statement about D.C. generators is false ? (a) Compensating winding in a D.C. machine helps in commutation (b) In a D. C. generator interpoles winding is connected in series with the armature winding (c) Back pitch and front pitch are both odd and approximately equal to the pole pitch (d) Equilizing bus bars are used with parallel running of D.C. shunt generators Ans: d 42. The demagnetising component of armature reaction in a D.C. generator (a) reduces generator e.m.f. (b) increases armature speed (c) reduces interpoles flux density (d) results in sparking trouble Ans: a 43. Magnetic field in a D.C. generator is produced by (a) electromagnets (b) permanent magnets (c) both (a) and (b) Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) none of the above Ans: a 44. The number of brushes in a commutator depends on (a) speed of armature (b) type of winding (c) voltage (d) amount of current to be collected Ans: d 45. Compensating windings are used in D.C. generators (a) mainly to reduce the eddy currents by providing local short-circuits (b) to provide path for the circulation of cooling air (c) to neutralise the cross-magnetising effect of the armature reaction (d) none of the above Ans: c 46. Which of the following components of a D.C, generator plays vital role for providing direct current of a D.C. generator ? (a) Dummy coils (b) Commutator (c) Eye bolt (d) Equilizer rings Ans: b 47. In a D.C. generator the ripples in the direct e.m.f. generated are reduced by (a) using conductor of annealed copper (b) using commutator with large number of segments (c) using carbon brushes of superior quality (d) using equiliser rings Ans: c 48. In D.C. generators, lap winding is used for (a) high voltage, high current (b) low voltage, high current (c) high voltage, low current (d) low voltage, low current Ans: b 49. Two generators A and B have 6-poles each. Generator A has wave wound armature while generator B has lap wound armature. The ratio of the induced e.m.f. is generator A and B will be (a) 2 : 3 Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) 3 : 1 (c) 3 : 2 (d) 1 : 3 Ans: b 50. The voltage drop for which of the following types of brush can be expected to be least ? (a) Graphite brushes (b) Carbon brushes (c) Metal graphite brushes (d) None of the above Ans: c 51. The e.m.f. generated by a shunt wound D.C. generator isE. Now while pole flux remains constant, if the speed of the generator is doubled, the e.m.f. generated will be (a) E/2 (b) 2E (c) slightly less than E (d) E Ans: b 52. In a D.C. generator the actual flux distribution depends upon (a) size of air gap (b) shape of the pole shoe (c) clearance between tips of the ad¬jacent pole shoes (d) all of the above Ans: 53. The armature core of a D.C. generator is usually made of (a) silicon steel (b) copper (c) non-ferrous material (d) cast-iron Ans: a 9.63. Satisfactory commutation of D.C. machines requires (a) brushes should be of proper grade and size (b) brushes should smoothly run in the holders (c) smooth, concentric commutator properly undercut (d) all of the above Ans: d 54. Open circuited armature coil of a D.C. machine is (a) identified by the scarring of the commutator segment to which open circuited coil is Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS connected (b) indicated by a spark completely around the commutator (c) both (a) and (b) (d) none of the above Ans: c 55. In a D.C. machine, fractional pitch winding is used (a) to increase the generated voltage (b) to reduce sparking (c) to save the copper because of shorter end connections (d) due to (b) and (c) above Ans: 56. For the parallel operation of two or more D.C. compound generators, we should ensure that (a) voltage of the incoming generator should be same as that of bus bar (b) polarity of incoming generator should be same as that of bus bar (c) all the series fields should be run in parallel by means of equilizer connection (d) series fields of all generators should be either on positive side or negative side of the armature (e) all conditions mentioned above should be satisfied Ans: d 57. D.C. series generator is used (a) to supply traction load (b) to supply industrial load at constant voltage (c) voltage at the toad end of the feeder (d) for none of the above purpose Ans: c 58. Following D.C. generator will be in a position to build up without any residual magnetism in the poles (a) series generator (b) shunt generator (c) compound generator (d) self-excited generator Ans: d 59. Interpole flux should be sufficient to (a) neutralise the commutating self induced e.m.f. (b) neutralise the armature reaction flux (c) neutralise both the armature reaction flux as well as commutating e.m.f. induced in the coil Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) perform none of the above functions Ans: c 60. D.C. generator generally preferred for charging automobile batteries is (a) series generator (b) shunt generator (c) long shunt compound generator (d) any of'the above Ans: c 61. In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when (a) r.p.m. is more than 300 (b) r.p.m. is less than 300 (c) number of poles is 4 (d) number of poles is 2 Ans: d 62. Permeance is the reciprocal of (a) flux density (b) reluctance (c) ampere-turns (d) resistance Ans: b 63. In D.C. generators the polarity of the interpoles (a) is the same as that of the main pole ahead (b) is the same as that of the immediately preceding pole (c) is opposite to that of the main pole ahead (d) is neutral as these poles do not play part in generating e.m.f. Ans: a 64. The e.m.f. generated in a D.C. generator is directly proportional to (a) flux/pole (b) speed of armature (c) number of poles (d) all of the above Ans: b 65. In a D.C. generator the magnetic neutral axis coincides with the geometrical neutral axis, when (a) there is no load on|he generator (b) the generator runs on full load Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) the generator runs on overload (d) the generator runs on designed speed Ans: a 66. In a D.C. generator in order to reduce sparking at brushes, the self-induced e.m.f. in the coil is neutralised by all of the following except (a) interpoles (b) dummy coils (c) compensating winding (d) shifting of axis of brushes Ans: b 67. In D.C. generators on no-load, the air gap flux distribution in space is (a) sinusoidal (b) triangular (c) pulsating (d) flat topped Ans: d 68. A shunt generator running at 1000 r.p.m. has generated e.m.f. as 200 V. If the speed increases to 1200 r.p.m., the generated e.m.f. will be nearly (a) 150 V (b) 175 V (c) 240 V (d) 290 V Ans: c 69. The purpose of providing dummy coils in a generator is (a) to reduce eddy current losses (b) to enhance flux density (c) to amplify voltage (d) to provide mechanical balance for the rotor Ans: d 70. In a shunt generator the voltage build up is generally restricted by (a) speed limitation (b) armature heating (c) insulation restrictions (d) saturation of iron Ans: 71. If a D.C. generator fails to build up the probable cause could not be (a) imperfect brush contact Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) field resistance less than the critical resistance (c) no residual magnetism in the generator (d) faulty shunt connections tending to reduce the residual magnetism Ans: b 72. Flashing the field of D.C. generator means (a) neutralising residual magnetism (b) creating residual magnetism by a D.C. source (c) making the magnetic losses of forces parallel (d) increasing flux density by adding extra turns of windings on poles Ans: b 73. The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be (a) 640 V (b) 620 V (c) 600 V (d) 580 V Ans: d 74. In a D.C. generator the critical resistance refers to the resistance of (a) brushes (b) field (c) armature (d) load Ans: b 75. To achieve sparkless commutation brushes of a D.C. generator are rockedm ahead so as to bring them (a) just ahead of magnetic neutral axis (b) in magnetic neutral axis (c) just behind the magnetic neutral axis Ans: a 76. Armature coil is short circuited by brushes when it lies (a) along neutral axis (b) along field axis (c) in any of the above positions (d) in none of the above positions Ans: a 77. A cumulatively compounded long shunt generator when operating as a motor would be (a) cumulatively compounded long shunt Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) differentially compounded long shunt (c) cumulatively compounded short shunt (d) differentially compounded short shunt Ans: b 78. To avoid formation of grooves in the commutator of a D.C. machine (a) the brushes of opposite polarity should track each other (b) the brushes of same polarity should track each other (c) brush position has no effect on the commutator grooving Ans: a 79. The following constitute short-circuit in the armature winding. (a) Insulation failure between two com-mutator bars (6) Insulation failure between two turns of a coil (c) Two of more turns of the same coil getting grounded (d) All of the above Ans: d 80. The rapid wear of brushes takes place due to (a) abrasion from dust (b) excessive spring pressure (c) rough commutator bars (d) high mica insulation between com-mutation bars (e) all of the above factors Ans: e 81. Number of tappings for each equilizer ring is equal to (a) number of pole pairs (b) number of poles (c) number of parallel paths (d) number of commutator segments Ans: a 82. A D.C. generator can be considered as (a) rectifier (b) primemover (c) rotating amplifier (d) power pump Ans: c 83. In any rotating machine that part which houses the conductors and in which e.m.f. induced is to be utilised is called (a) rotor Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) stator (c) field (d) armature Ans: d 84. In a D.C. machine stray loss is the sum of (a) total copper loss and mechanical loss (b) armature copper loss and iron loss (c) shunt field copper loss and mechanical loss (d) iron loss and mechanical loss Ans: d 85. Lap winding is composed of (a) any even number of conductors (b) any odd number of conductors (c) that even number which is exact multiple of poles + 2 (d) that even number which is exact multiple of poles Ans: a 86. In a D.C. generator in case the resistance of the field winding is increased, then output voltage will (a) increase (b) decrease (c) remain unaffected (d) fluctuate heavily Ans: b 87. An exciter for a turbo generator is a (a) separately excited generator (b) shunt generator (c) series generator (d) compound generator Ans: b 88. In case of a flat compounded generator (a) voltage generated is less than the rated voltage (b) generated voltage is proportional to the load on the generator (c) voltage remains constant irrespec¬tive of the load (d) speed varies in proportion to the load on the generator Ans: c 89. Which of the following generator will have negligible terminal voltage while running on no-load ? Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) Series generator (b) Shunt generator (c) Compound generator (d) Separately excited generator Ans: a 90. Which of the following D.C. generators will be in a position to build up without any residual magnetism in the poles ? (a) Series generator (b) Shunt generator (c) Compound generator (d) None of the above Ans: d 91. In over compounded generator, full load terminal voltage is (a) almost zero (b) less than noload terminal voltage (c) more than noload terminal voltage (d) equal to no-load terminal voltage Ans: c 92. In a level compounded D.C. generator, full load terminal voltage is (a) negligibly low (b) equal to no-load terminal voltage (c) more than no-load terminal voltage (d) less than no-load terminal voltage Ans: b 93. The terminal voltage of a D.C. shunt generator drops on load because of all of the following reasons except (a) armature reaction (b) armature resistance drop (c) field weakening due to armature reaction and armature (d) commutation Ans: d 94. In a D.C. generator (a) external resistance = internal char-acteristic - armature reaction (b) internal characteristic = magnetisation characteristic - ohmic drop (c) external characteristic = magnetisation characteristic - ohmic drop - armature reaction (d) magnetisation characteristic = external characteristic Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 95. A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave (a) will be zero (b) will be of 5 Hz (c) willbeof5xiVHz (d) will be of v Hz 5 Ans: b 96. A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be (a) zero (b) about 2 V (c) about 50 V (d) 220 V Ans: b 97. In a separately excited generator supplying rated load the armature reaction , (a) is always present (b) is always absent (c) may be sometimes present (d) none of the above Ans: a 98. If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be (a) zero (b) small (c) the same as rated voltage (d) high Ans: a 99. Armature reaction in a generator results in (a) demagnetisation of leading pole tip and magnetisation of trailing pole tip (b) demagnetisation of trailing pole tip and magnetisation of leading pole tip (c) damagnetising the centre of all poles (d) magnetising the centre of all poles Ans: a 100. Following energized winding of a D.C. machine should not be opened as it would produce high inductive voltage which may be dangerous to personnel and may cause its own insulation failure. (a) Series field (b) Compensating field Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) Inter pole field (d) Shunt field Ans: d 101. Wave winding is composed of (a) any even number of conductors (b) any odd number of conductors (c) that even number which is exact multiple of poles + 2 (d) that even number which is exact multiple of poles Ans: c 102. The critical resistance of the D.C. generator is the resistance of (a) field (b) brushes (c) armature (d) load Ans: a 103. When two D.C. series generators are running in parallel, an equilizer bar is used (a) to increase the speed and hence generated e.m.f. (b) to increase the series flux (c) so that two similar machines will pass approximately equal currents to the load (d) to reduce the combined effect of ar-mature reaction of both machines Ans: c 104. Which of the following generating machine will offer constant voltage on all loads ? (a) Self-excited generator (b) Separately excited generator (c) Level compounded generator . (d) All of the above Ans: c 105. Which of the following generators will be preferred if they are required to be run in parallel ? (a) Shunt generators (b) Series generators (c) Compound generators (d) None of the above Ans: a 106. Two generators are running in parallel. One of the generators may run as motor for which of the following reasons ? (a) The direction of that generator is reversed Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) The speed of that generator is increased (c) The field of that generator is weakened (d) That generator takes large share of loads Ans: d 107. A D.C. generator works on the principle of (a) Lenz's law (b) Ohm's law (c) Faraday's law of electromagnetic induction (d) none of the above Ans: c 108. A series generator can self-excite (a) only if the load current is zero (b) only if the load current is not zero (c) irrespective of the value of load current (d) none of the above Ans: b 109. A shunt generator can self-excite (a) only if the resistance of the field circuit is less than critical value (b) only if the resistance of the field circuit is greater than critical value (c) irrespective of the value of the resis-tance in the field circuit Ans: a 110. The terminal voltage of a series generator is 150 V when the load current is 5 A. If the load current is increased to 10 A, the terminal voltage will be (a) 150 V (b) less than 150 V (c) greater than 150 V (d) none of the above Ans: c 111. The open circuit voltage of a compound generator is 250 V. At full load the terminal voltage (a) will be less than 250 V (b) will always be 250 V (c) may be greater or less than 250 V (d) none of the above Ans: c 112. Two D.C. shunt generators, each with armature resistance of 0.02 ohm and field resistance of 50 ohm run in parallel and supply a total current of 1000 amperes to the load Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS circuit. If their e.m.fs. are 270 V and 265 V, their bus bar voltage will be (a) 270 V (b) 267.5 V (c) 265 V (d) 257.4 V Ans: b 113. The essential condition for parallel operation of two D.C. generators is that they have ' (a) same kW rating (b) the same operation r.p.m. (c) the same drooping voltage charac-teristics (d) same percentage regulation Ans: c 114. When two D.C. generators are running in parallel an equilizer bar is used (a) to increase the series flux (b) to increase the generated e.m.f. (c) to reduce the combined effect of ar-mature reaction of both the machines (d) so that the two identical machines will pass approximately equal currents to the load Ans: d 115. With a D.C. generator which of the following regulation is preferred ? (a) 100% regulation (b) infinite regulation (c) 50% regulation (d) 1% regulation Ans: d 116. Which generator would you prefer for feeding long D.C. transmission lines ? (a) Series generator (b) Shunt generator (c) Over compound generator (d) Flat compound generator Ans: c 117. In a D.C. generator the critical resistance can be increased by (a) increasing its field resistance (b) decreasing its field resistance (c) increasing its speed (d) decreasing its speed Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 118. The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is (a) 2 (b) 4 (c) 6 (d) 8 Ans: b 119. For both lap and wave windings, there are as many commutator bars as the number of (a) slots (b) armature conductors (c) winding elements (d) poles Ans: c 120. The series field of a short-shunt D.C. generator is excited by (a) external current (b) armature current (c) shunt current (d) load current Ans: d 121. As a result of armature reaction, the reduction in the total mutual air gap flux in a D.C. generator is approximately (a) 40 percent (b) 25 percent (c) 10 percent (d) 5 percent Ans: d 122. Shunt generators are most suited for stable parallel operation because of their (a) rising voltage characteristics (b) identical voltage characteristics (c) drooping voltage characteristics (d) linear voltage characteristics Ans: c 123. The main factor which leads to unstable parallel operation of flat and over compounded generators is (a) their rising voltage characteristics (b) unequal number of turns in their series field windings (c) unequal speed regulation of their primemovers (d) unequal series field resistances Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: a 124. If a self excited D.C. generator after being installed, fails to build up on its first trial run, the first thing to do is to (a) reverse the field connections (b) increase the field resistance (c) increase the speed of primemover (d) check armature insulation resis¬tance Ans: a 1. B. DC MOTOR 1. No-load speed of which of the following motor will be highest ? (a) Shunt motor (b) Series motor (c) Cumulative compound motor (d) Differentiate compound motor Ans: b 2. The direction of rotation of a D.C. series motor can be changed by (a) interchanging supply terminals (b) interchanging field terminals (c) either of (a) and (b) above (d) None of the above Ans: b 3. Which of the following application requires high starting torque ? (a) Lathe machine (b) Centrifugal pump (c) Locomotive (d) Air blower Ans: c 4. If a D.C. motor is to be selected for conveyors, which rriotor would be preferred ? (a) Series motor (b) Shunt motor (c) Differentially compound motor (d) Cumulative compound motor Ans: a 5. Which D.C. motor will be preferred for machine tools ? (a) Series motor (b) Shunt motor Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) Cumulative compound motor (d) Differential compound motor Ans: b 6. Differentially compound D.C. motors can find applications requiring (a) high starting torque (b) low starting torque (c) variable speed (d) frequent on-off cycles Ans: b 7. Which D.C. motor is preferred for elevators ? (a) Shunt motor (b) Series motor (c) Differential compound motor (d) Cumulative compound motor Ans: d 8. According to Fleming's left-hand rule, when the forefinger points in the direction of the field or flux, the middle finger will point in the direction of (a) current in the conductor aovtaat of conductor (c) resultant force on conductor (d) none of the above Ans: a 9. If the field of a D.C. shunt motor gets opened while motor is running (a) the speed of motor will be reduced % (b) the armature current will reduce (c) the motor will attain dangerously high speed 1 (d) the motor will continue to nuvat constant speed Ans: c 10. Starters are used with D.C. motors because (a) these motors have high starting torque (b) these motors are not self-starting (c) back e.m.f. of these motors is zero initially (d) to restrict armature current as there is no back e.m.f. while starting Ans: d 11. In D.C. shunt motors as load is reduced (a) the speed will increase abruptly (b) the speed will increase in proportion to reduction in load (c) the speed will remain almost/constant Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) the speed will reduce Ans: c 12. A D.C. series motor is that which (a) has its field winding consisting of thick wire and less turns (b) has a poor torque (c) can be started easily without load (d) has almost constant speed Ans: a 13. For starting a D.C. motor a starter is required because (a) it limits the speed of the motor (b) it limits the starting current to a safe value (c) it starts the motor (d) none of the above Ans: b 14. The type of D.C. motor used for shears and punches is (a) shunt motor (b) series motor (c) differential compoutid D.C. motor (d) cumulative compound D.C. motor Ans: d 15. If a D.C. motor is connected across the A.C. supply it will (a) run at normal speed (b) not run (c) run at lower speed (d) burn due to heat produced in the field winding by .eddy currents Ans: d 16. To get the speed of D.C, motor below the normal without wastage of electrical energy is used. (a) Ward Leonard control (b) rheostatic control (c) any of the above method (d) none of the above method Ans: a 17. When two D.C. series motors are connected in parallel, the resultant speed is (a) more than the normal speed (b) loss than the normal speed (c) normal speed Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) zero Ans: c 18. The speed of a D.C. shunt motor more than its full-load speed can be obtained by (a) decreasing the field current (b) increasing the field current (c) decreasing the armature current (d) increasing the armature current Ans: a 19. In a D.C. shunt motor, speed is (a) independent of armature current (b) directly proportional to the armature current (c) proportional to the square of the current (d) inversely proportional to the armature current Ans: a 20. A direct on line starter is used: for starting motors (a) iip to 5 H.P. (b) up to 10 H.P. (c) up to 15 H.P. (d) up to 20 H.P. Ans: a 21. What will happen if the back e.m.f. of a D.C. motor vanishes suddenly? (a) The motor will stop (b) The motor will continue to run (c) The armature may burn (d) The motor will run noisy Ans: c 22. In case of D.C. shunt motors the speed is dependent on back e.m.f. only because (a) back e.m.f. is equal to armature drop (b) armature drop is negligible (c) flux is proportional to armature current (d) flux is practically constant in D:C. shunt motors Ans: d 23. In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be (a) almost negligible (b) rated full-load current (c) less than full-load current Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) more than full-load current Ans: d 24. These days D.C. motors are widely used in (a) pumping sets (b) air compressors (c) electric traction (d) machine shops Ans: c 25. By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor? (a) Frame (b) Shaft (c) Commutator (d) Stator Ans: c 26. In which of the following applications D.C. series motor is invariably tried? (a) Starter for a car (b) Drive for a water pump (c) Fan motor (d) Motor operation in A.C. or D.C. Ans: a 27. In D.C. machines fractional pitch winding is used (a) to improve cooling (b) to reduce copper losses (c) to increase the generated e.m.f. (d) to reduce the sparking Ans: d 28. A three point starter is considered suitable for (a) shunt motors (b) shunt as well as compound motors (c) shunt, compound and series motors (d) all D.C. motors Ans: b 29. In case-the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be (a) 100% (b) around 90% Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) anywhere between 75% and 90% (d) less than 50% Ans: d 30. The ratio of starting torque to full-load torque is least in case of (a) series motors (b) shunt motors (c) compound motors (d) none of the above Ans: b 32. In D.C. motor which of the following can sustain the maximum temperature rise? (a) Slip rings (b) Commutator (c) Field winding (d) Armature winding Ans: c 33. Which of the following law/rule can he used to determine the direction of rotation of D.C. motor ? (a) Lenz's law (b) Faraday's law (c) Coloumb's law (d) Fleming's left-hand rule Ans: d 34. Which of the following load normally needs starting torque more than the rated torque? (a) Blowers (b) Conveyors (c) Air compressors (d) Centrifugal pumps Ans: b 35. The starting resistance of a D.C. motor is generally (a) low (b) around 500 Q (c) 1000 Q (d) infinitely large Ans: a 36. The speed of a D.C. series motor is (a) proportional to the armature current Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) proportional to the square of the armature current (c) proportional to field current (d) inversely proportional to the armature current Ans: d 37. In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to (a) 100% of the previous value (b) 50% of the previous value (c) 25% of the previous value (d) 10% of the previous value (e) none of the above Ans: c 38. The current drawn by the armature of D.C. motor is directly proportional to (a) the torque required (b) the speed of the motor (c) the voltage across the terminals (d) none of the above Ans: a 39. The power mentioned on the name plate of an electric motor indicates (a) the power drawn in kW (b) the power drawn in kVA (c) the gross power (d) the output power available at the shaft Ans: d 40. Which D.C. motor has got maximum self loading property? (a) Series motor (b) Shunt motor (c) Cumulatively compounded 'motor (d) Differentially compounded motor Ans: d 41. Which D.C. motor will be suitable alongwith flywheel for intermittent light and heavy loads? (a) Series motor (b) Shunt motor (c) Cumulatively compounded motor (d) Differentially compounded motor Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 42. If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens (a) nothing will happen to th£ motor (b) this will make armature to take heavy current, possibly burning it (c) this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses (d) motor will run at very slow speed Ans: c 43. D.C. series motors are used (a) where load is constant (b) where load changes frequently (c) where constant operating speed is needed (d) in none of the above situations. Ans: d 44. For the same H.P. rating and full load speed, following motor has poor starting torque (a) shunt (b) series (c) differentially compounded (d) cumulativelyc'ompounded Ans: c 45. In case of conductively compensated D.C. series motors, the compensating winding is provided (a) as separately wound unit (6) in parallel with armature winding (c) in series with armature winding (d) in parallel with field winding Ans: c 46. Sparking at the commutator of a D.C. motor may result in (a) damage to commutator segments (b) damage to commutator insulation (c) increased power consumption (d) all of the above Ans: d 47. Which of the following motor is preferred for operation in highly explosive atmosphere ? (a) Series motor (b) Shunt motor (c) Air motor (d) Battery operated motor Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: c 48. If the supply voltage for a D.C. motor is increased, which of the following will decrease ? (a) Starting torque (b) Operating speed (c) Full-load current (d) All of the above Ans: c 49. Which one of the following is not the function of pole shoes in a D.C. machine ? (a) To reduce eddy current loss (b) To support the field coils (c) To spread out flux for better unifor-mity (d) To reduce the reluctance of the mag-netic path Ans: a 50. The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is (a) 4.0 (b) 2.0 (c) 1.0 (d) 0.5 Ans: d 51. The condition for maximum power in case of D.C. motor is (a) back e.m.f. = 2 x supply voltage (b) back e.m.f. = | x supply voltage (c) supply voltage = | x back e.m.f. (d) supply voltage = back e.m.f. Ans: b 52. For which of the following applications a D.C. motor is preferred over an A.C. motor ? (a) Low speed operation (b) High speed operation (c) Variable speed operation (d) Fixed speed operation Ans: c 53. In D.C. machines the residual magnetism is of the order of (a) 2 to 3 per cent (6) 10 to 15 per cent (c) 20 to 25 per cent Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) 50 to 75 per cent Ans: a 54. Which D.C. motor is generally preferred for cranes and hoists ? (a) Series motor (b) Shunt motor (c) Cumulatively compounded motor (d) Differentially compounded motor Ans: a 55. Three point starter can be used for (a) series motor only (b) shunt motor only (c) compound motor only (d) both shunt and compound motor Ans: d 56. Sparking, is discouraged in a D.C. motor because (a) it increases the input power con-sumption (b) commutator gets damaged (c) both (a) and (b) (d) none of the above Ans: b 57. Speed control by Ward Leonard method gives uniform speed variation (a) in one direction (b) in both directions (c) below normal speed only (d) above normal speed only. Ans: b 58. Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be (a) level compounded (b) under compounded (c) cumulatively compounded (d) differentially compounded Ans: c 59. Following motor is used where high starting torque and wide speed range control is required. (a) Single phase capacitor start (b) Induction motor Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) Synchronous motor (d) D.C. motor (e) None of the above Ans: d 60. In a differentially compounded D.C. motor, if shunt field suddenly opens (a) the motor will first stop and then run in opposite direction as series motor (b) the motor will work as series motor and run at slow speed in the same direction (c) the motor will work as series motor and run at high speed in the same direction (d) the motor will not work and come to stop Ans: a 61. Which of the following motor has the poorest speed regulation ? (a) Shunt motor (b) Series motor (c) Differential compound motor (d) Cumulative compound motor Ans: b 62. Buses, trains, trolleys, hoists, cranes require high starting torque and therefore make use of (a) D.C. series motor (b) D.C. shunt motor (c) induction motor (d) all of above motors Ans: a 63. As -the load is increased the speed of D.C. shunt motor will (a) reduce slightly (b) increase slightly (c) increase proportionately (d) remains unchanged Ans: a 64. The armature torque of the D.C. shunt motor is proportional to (a) field flux only (b) armature current only (c) both (a) and (b) (d) none of the above Ans: b 65. Which of the following method of speed control of D.C. machine will offer minimum efficiency ? Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) Voltage control method (b) Field control method (c) Armature control method (d) All above methods Ans: c 66. Usually wide and sensitive speed control is desired in case of (a) centrifugal pumps (b) elevators (c) steel rolling mills (d) colliery winders Ans: d 67. The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. The speed regulation of the motor is (a) 2.36% (6) 4.76% (c) 6.77% (d) 8.84% Ans: b 68. The armature voltage control of D.C. motor provides (a) constant torque drive (b) constant voltage drive (c) constant current drive (d) none of the above Ans: a 69. As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit (a) a resistance is connected in series with armature (b) a resistance is connected parallel to the armature (c) armature is temporarily open circuited (d) a high value resistor is connected across the field winding Ans: a 70. The speed of a D.C. shunt motor can be increased by (a) increasing the resistance in armature circuit (b) increasing the resistance in field circuit (c) reducing the resistance in the field circuit (d) reducing the resistance in the armature circuit Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 71. If I2 be the armature current, then speed of a D.C. shunt motor is (a) independent of Ia (b) proportional to la (c) varies as (Ia) (d) varies as la Ans: a 72. In case the back e.m.f. and the speed of a D.C. motor are doubled, the torque developed by the motor will (a) remain unchanged (6) reduce to one-fourth value (c) increase four folds (d) be doubled Ans: a 73. At the instant of starting when a D.C. motor is put on supply, it behaves like (a) a highly resistive circuit (6) a low resistance circuit (c) a capacitive circuit (d) none of the above Ans: b 74. The speed of a D.C. motor can be varied by varying (a) field current (b) applied voltage (c) resistance in series with armature (d) any of the above Ans: d 75. Which one of the following is not necessarily the advantage of D.C. motors over A.C. motors ? (a) Low cost (b) Wide speed range (c) Stability (d) High starting torque. Ans: a 76. For a D.C. shunt motor if the excitation is changed (a) torque will remain constant (b) torque will change but power will remain constant (c) torque and power both will change (d) torque, power and speed, all will change Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 77. Which motor has the poorest speed control? (a) Differentially compounded motor (b) Cumulatively compounded motor (c) Shunt motor (d) Series motor Ans: d 78. The plugging gives the (a) zero torque braking (b) smallest torque braking (c) highest torque braking (d) none of the above Ans: c 79. The armature voltage control of D.C. motor provides (a) constant voltage drive (b) constant current drive (c) constant torque drive (d) none of the above Ans: c 80. If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor (a) of lower H.P. should be selected (6) of higher H.P. should be selected (c) can be used for 50°C ambient temperature also (d) is to be derated by a factor recom-mended by manufacturer and select the next higher H.P. motor Ans: d 81. If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking (o) regenerative (b) plugging (c) dynamic braking (d) none of the above (e) any of the above Ans: b 82. Which of the following motors one will choose to drive the rotary compressor ? (a) D.C. shunt motor (b) D.C. series motor Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) Universal motor (d) Synchronous motor Ans: d 83. If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will (a) increase (b) decrease (c) remain same (d) become zero Ans: a 84. Why are the D.C. motors preferred for traction applications ? (a) Torque and speed are inversely proportional to armature current (b) Torque is proportional to armature current (c) Torque is proportional to square root of armature current (d) The speed is inversely proportional to the torque and the torque is proportional to square of armature current Ans: d 85. Which of the following motors is usually used in house-hold refrigerators ? (a) D.C. shunt motor (b) D.C. series motor (c) Single phase induction motor (split phase start or induction run motor) (d) Reluctance motor (e) Synchronous motor Ans: c 86. Which of the following motors is most suitable for signalling devices and many kinds of timers ? (a) D.C. shunt motor (b) D.C. series motor (c) Induction motor (d) Reluctance motor Ans: d 87. Which motor should not be started on no-load ? (a) Series motor (b) Shunt motor (c) Cumulatively compounded motor (d) Differentially compounded motor. Ans: a 88. Ward-Leonard control is basically a Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) voltage control method (b) field divertor method (c) field control method (d) armature resistance control method Ans: a 89. For constant torque drive which speed control method is preferred ? (a) Field control (b) Armature voltage control (c) Shunt armature control (d) Mechanical loading system Ans: b 90. In Ward-Leonard control the lower limit of speed is imposed by (a) residual magnetism of the generator (b) core losses of motor (c) mechanical losses of motor and gen¬erator together (d) all of the above Ans: a 91. The main disadvantage of the Ward-Leonard control method is (a) high initial cost (b) high maintenance cost (c) low efficiency at Hght loads (d) all of the above Ans: d 92. Regenerative method of braking is based on that (a) back e.m.f. is less than the applied voltage (b) back e.m.f. is equal to the applied voltage (c) back e.m.f. of rotor is more than the applied voltage (d) none of the above Ans: b 93. The hysteresis loss in a D.C. machine least depends on (a) Frequency of magnetic reversals (b) Maximum value of flux density (c) Volume and grade of iron (d) Rate of flow of ventilating air Ans: d 94. In a D.C. generator all of the following could be the effects of iron losses except (a) Loss of efficiency Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) Excessive heating of core (c) Increase in terminal voltage (d) Rise in temperature of ventilating air Ans: c 95. The losses occurring in a D.C. generator are given below. Which loss is likely to have highest proportion at rated load of the generator ? (a) hysteresis loss (b) field copper loss (c) armature copper loss (d) eddy current loss Ans: c 96. Which of the following loss in a D.C. generator varies significantly with the load current ? (a) Field copper loss (b) Windage loss (c) Armature copper loss (d) None of the above Ans: c 97. Torque developed by a D.C. motor depends upon (a) magnetic field (b) active length of the conductor (c) current flow through the conductors (d) number of conductors (e) radius of armature (f) all above factors Ans: f 98. D.C. shunt motors are used for driving (a) trains (b) cranes (c) hoists (d) machine tools Ans: d 99. In a manual shunt motor starter (a) over load relay is connected in series and no volt relay in parallel with the load (6) over load relay is connected in paral¬lel and no volt relay in series with the load (c) over load relay and no volt relay are both connected in series with the load (d) over load relay and no volt relay are both connected in parallel with the load Ans: a Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 100. Which of the following steps is likely to result in reduction of hysteresis loss in a D.C. generator ? (a) Providing laminations in armature core (b) Providing laminations in stator (c) Using non-magnetic material for frame (d) Using material of low hysteresis co-efficient for armature core material Ans: d 101. Which of the following loss in a D.C. generator is dissipated in the form of heat? (a) Mechanical loss (b) Core loss (c) Copper loss (d) All of the above Ans: d 102. Which of the following losses are significantly reduced by laminating the core of a D.C. generator ? (a) Hysteresis losses (b) Eddy current losses (c) Copper losses (d) Windage losses Ans: b 103. The total losses in a well designed D.C. generator of 10 kW will be nearly (a) 100 W (b) 500 W (c) 1000 W (d) 1500 W Ans: b 104. The condition for maximum efficiency for a D.C. generator is (a) eddy current losses = stray losses (b) hysteresis losses = eddy current losses (c) copper losses = 0 (d) variable losses = constant losses Ans: d 105. D.C. generators are normally designed for maximum efficiency around (a) full-load (b) rated r.p.m. (c) rated voltage (d) all of the above Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: a 106. In a D.C. generator, the iron losses mainly take place in (a) yoke (b) commutator (c) armature conductors (d) armature rotor Ans: d 107. D.C. generators are installed near the load centres to reduce (a) iron losses (b) line losses (c) sparking (d) corona losses Ans: b 108. The purpose of retardation test on D.C. shunt machines is to find out (a) stray losses (b) eddy current losses (c) field copper losses (d) windage losses Ans: a 109. Which of the following tests will be suitable for testing two similar D.C. series motors of large capacity ? (a) Swinburne's test (b) Hopkinson's test (c) Field test (d) Brake test Ans: c 110. Hopkinson's test on D.C. machines is conducted at (a) no-load (b) part load (c) full-load (d) overload Ans: c 111. During rheostat braking of D.C. series motors (a) motor is run as a generator (b) motor is reversed in direction (c) motor is run at reduced speed Ans: a Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 112. For which types of D.C. motor, dynamic braking is generally used ? (a) Shunt motors (b) Series motors (c) Compound motors (d) All of the above Ans: d 113. Which method of braking is generally used in elevators ? (a) Plugging (b) Regenerative braking (c) Rheostatic braking (d) None of the above Ans: a 114. In variable speed motor (a) a stronger commutating field is needed at low speed than at high speed (b) a weaker commutating field is needed at low speed than at high speed (c) same commutating field is needed at low speed than at high speed (d) none of the above is correct Ans: b 115. When the armature of a D.C. motor rotates, e.m.f. induced is (a) self-induced e.m.f. (b) mutually induced e.m.f. (c) back e.m.f. (d) none of the above Ans: c 116. Where D.C. motor of H.P. 12 or more requires frequent starting, stopping, reversing and speed control (a) drum type controller is used (b) three point starter is used (c) four point starter is used (d) all above can be used Ans: a 117. If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens (a) this will make armature to take heavy current, possibly burning it (6) this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses (c) nothing will happen to motor (d) motor will come to stop Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: a 118. D.C. motor is to drive a load which has certain minimum value for most of the time and some peak value for short duration. We will select the (a) series motor (b) shunt motor (c) compound motor (d) any of the above Ans: a 119. D.C. motor is to a drive a load which is almost nil for certain part of the load cycle and peak value for short duration. We will select this (a) series motor (b) shunt motor (c) compound motor (d) any of the above Ans: c 120. Which D.C. motor has got maximum self relieving property ? (a) Series motor (6) Shunt motor (c) Cumulatively compounded motor (d) Differentially compounded motor Ans: a 121. In the D.C. motor the iron losses occur in (a) the field (b) the armature (c) the brushes (d) the commutator Ans: b 122. The speed of a D.C. shunt motor is required to be more than full load speed. This is possible by (a) reducing the field current (b) decreasing the armature current (c) increasing the armature current (d) increasing the excitation current (e) none of the above methods Ans: a 123. One D.C. motor drives another D.C. motor. The second D.C. motor when excited and Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS driven (a) runs as a generator (b) does not run as a generator (c) also runs as a motor comes to stop after sometime Ans: a 2. TRANSFORMERS 1. Which of the following does not change in a transformer ? (a) Current (b) Voltage (c) Frequency (d) All of the above Ans: c 2. In a transformer the energy is conveyed from primary to secondary (a) through cooling coil (b) through air (c) by the flux (d) none of the above Ans: c 3. A transformer core is laminated to (a) reduce hysteresis loss (b) reduce eddy current losses (c) reduce copper losses (d) reduce all above losses Ans: b 4. The degree of mechanical vibrations produced by the laminations of a transformer depends on (a) tightness of clamping (b) gauge of laminations (c) size of laminations (d) all of the above Ans: d Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 5. The no-load current drawn by transformer is usually what per cent of the full-load current ? (a) 0.2 to 0.5 per cent (b) 2 to 5 per cent (c) 12 to 15 per cent (d) 20 to 30 per cent Ans: b 6. The path of a magnetic flux in a transformer should have (a) high resistance (b) high reluctance (c) low resistance (d) low reluctance Ans: d 7. No-load on a transformer is carried out to determine (a) copper loss (b) magnetising current (c) magnetising current and loss (d) efficiency of the transformer Ans: c 8. The dielectric strength of transformer oil is expected to be (a) lkV (b) 33 kV (c) 100 kV (d) 330 kV Ans: b 9. Sumpner's test is conducted on trans-formers to determine (a) temperature (b) stray losses (c) all-day efficiency (d) none of the above Ans: a 10. The permissible flux density in case of cold rolled grain oriented steel is around Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) 1.7 Wb/m2 (b) 2.7 Wb/m2 (c) 3.7 Wb/m2 (d) 4.7 Wb/m2 Ans: a The efficiency of a transformer will be maximum when (a) copper losses = hysteresis losses (b) hysteresis losses = eddy current losses (c) eddy current losses = copper losses (d) copper losses = iron losses Ans: d 12. No-load current in a transformer (a) lags behind the voltage by about 75° (b) leads the voltage by about 75° (c) lags behind the voltage by about 15° (d) leads the voltage by about 15° Ans: a 13. The purpose of providing an iron core in a transformer is to (a) provide support to windings (b) reduce hysteresis loss (c) decrease the reluctance of the magnetic path (d) reduce eddy current losses Ans: c 14. Which of the following is not a part of transformer installation ? (a) Conservator (b) Breather (c) Buchholz relay (d) Exciter Ans: d 15. While conducting short-circuit test on a transformer the following side is short circuited (a) High voltage side (b) Low voltage side Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) Primary side (d) Secondary side Ans: b 16. In the transformer following winding has got more cross-sectional area (a) Low voltage winding (b) High voltage winding (c) Primary winding (d) Secondary winding Ans: a 17. A transformer transforms (a) voltage (b) current (c) power (d) frequency Ans: c 18. A transformer cannot raise or lower the voltage of a D.C. supply because (a) there is no need to change the D.C. voltage (b) a D.C. circuit has more losses (c) Faraday's laws of electromagnetic induction are not valid since the rate of change of flux is zero (d) none of the above Ans: c 19. Primary winding of a transformer (a) is always a low voltage winding (b) is always a high voltage winding (c) could either be a low voltage or high voltage winding (d) none of the above Ans: c 20. Which winding in a transformer has more number of turns ? (a) Low voltage winding (b) High voltage winding (c) Primary winding (d) Secondary winding Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: b 21. Efficiency of a power transformer is of the order of (a) 100 per cent (b) 98 per cent (c) 50 per cent (d) 25 per cent Ans: b 22. In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are (a) friction and windage losses (b) copper losses (c) hysteresis and eddy current losses (d) none of the above Ans: c 23. A common method of cooling a power transformer is (a) natural air cooling (b) air blast cooling (c) oil cooling (d) any of the above Ans: c 24. The no load current in a transformer lags behind the applied voltage by an angle of about (a) 180° (b) 120" (c) 90° (d) 75° Ans: d 25. In a transformer routine efficiency depends upon (a) supply frequency (b) load current (c) power factor of load (d) both (b) and (c) Ans: d Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 26. In the transformer the function of a conservator is to (a) provide fresh air for cooling the transformer (b) supply cooling oil to transformer in time of need (c) protect the transformer from damage when oil expends due to heating (d) none of the above Ans: c 27. Natural oil cooling is used for transformers upto a rating of (a) 3000 kVA (b) 1000 kVA (c) 500 kVA (d) 250 kVA Ans: a 28. Power transformers are designed to have maximum efficiency at (a) nearly full load (b) 70% full load (c) 50% full load (d) no load Ans: a 29. The maximum efficiency of a distribution transformer is (a) at no load (b) at 50% full load (c) at 80% full load (d) at full load Ans: b 30. Transformer breaths in when (a) load on it increases (b) load on it decreases (c) load remains constant (d) none of the above Ans: b 31. No-load current of a transformer has (a) has high magnitude and low power factor Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) has high magnitude and high power factor (c) has small magnitude and high power factor (d) has small magnitude and low power factor Ans: d 32. Spacers are provided between adjacent coils (a) to provide free passage to the cool¬ing oil (b) to insulate the coils from each other (c) both (a) and (b) (d) none of the above Ans: a 33. Greater the secondary leakage flux (a) less will be the secondary induced e.m.f. (b) less will be the primary induced e.m.f. (c) less will be the primary terminal voltage (d) none of the above Ans: a 34. The purpose of providing iron core in a step-up transformer is (a) to provide coupling between primary and secondary (b) to increase the magnitude of mutual flux (c) to decrease the magnitude of mag-netizing current (d) to provide all above features Ans: c 35. The power transformer is a constant (a) voltage device (b) current device (c) power device (d) main flux device Ans: d 36. Two transformers operating in parallel will share the load depending upon their (a) leakage reactance (b) per unit impedance (c) efficiencies (d) ratings Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: b 37. If R2 is the resistance of secondary winding of the transformer and K is the transformation ratio then the equivalent secondary resistance referred to primary will be (a) R2/VK (b) R2IK2 (c) R22!K2 (d) R22/K Ans: b 38. What will happen if the transformers working in parallel are not connected with regard to polarity ? (a) The power factor of the two trans-formers will be different from the power factor of common load (b) Incorrect polarity will result in dead short circuit (c) The transformers will not share load in proportion to their kVA ratings (d) none of the above Ans: b 39. Ifthe percentage impedances of the two transformers working in parallel are different, then (a) transformers will be overheated (b) power factors of both the trans-formers will be same (c) parallel operation will be not possible (d) parallel operation will still be possible, but the power factors at which the two transformers operate will be different from the power factor of the common load Ans: d 40. In a transformer the tappings are generally provided on (a) primary side (b) secondary side (c) low voltage side (d) high voltage side Ans: c 41. The use of higher flux density in the transformer design (a) reduces weight per kVA (6) reduces iron losses Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) reduces copper losses (d) increases part load efficiency Ans: a 42. The chemical used in breather for transformer should have the quality of (a) ionizing air (b) absorbing moisture (c) cleansing the transformer oil (d) cooling the transformer oil. Ans: b 43. The chemical used in breather is (a) asbestos fibre (b) silica sand (c) sodium chloride (d) silica gel Ans: d 44. An ideal transformer has infinite values of primary and secondary inductances. The statement is (a) true (b) false Ans: b 45. The transformer ratings are usually expressed in terms of (a) volts (b) amperes (c) kW (d) kVA Ans: d 46. The noise resulting from vibrations of laminations set by magnetic forces, is termed as (a) magnetostrication (b) boo (c) hum (d) zoom Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 47. Hysteresis loss in a transformer varies as CBmax = maximum flux density) (a) Bmax (b) Bmax1-6 (C) Bmax1-83 (d) B max Ans: b 48. Material used for construction of transformer core is usually (a) wood (b) copper (c) aluminium (d) silicon steel Ans: d 49. The thickness of laminations used in a transformer is usually (a) 0.4 mm to 0.5 mm (b) 4 mm to 5 mm (c) 14 mm to 15 mm (d) 25 mm to 40 mm Ans: a 50. The function of conservator in a transformer is (a) to project against'internal fault (b) to reduce copper as well as core losses (c) to cool the transformer oil (d) to take care of the expansion and contraction of transformer oil due to variation of temperature of sur-roundings Ans: d 51. The highest voltage for transmitting electrical power in India is (a) 33 kV. (6) 66 kV (c) 132 kV (d) 400 kV Ans: d 52. In a transformer the resistance between its primary and secondary is (a) zero Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) 1 ohm (c) 1000 ohms (d) infinite Ans: d 53. A transformer oil must be free from (a) sludge (b) odour (c) gases (d) moisture Ans: d 54. A Buchholz relay can be installed on (a) auto-transformers (b) air-cooled transformers (c) welding transformers (d) oil cooled transformers Ans: d 55. Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds (a) 50°C (b) 80°C (c) 100°C (d) 150°C Ans: d 56. The main reason for generation of harmonics in a transformer could be (a) fluctuating load (b) poor insulation (c) mechanical vibrations (d) saturation of core Ans: d 57. Distribution transformers are generally designed for maximum efficiency around (a) 90% load (b) zero load (c) 25% load Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) 50% load Ans: d 58. Which of the following property is not necessarily desirable in the material for transformer core ? (a) Mechanical strength (6) Low hysteresis loss (c) High thermal conductivity (d) High permeability Ans: c 59. Star/star transformers work satisfactorily when (a) load is unbalanced only (b) load is balanced only (c) on balanced as well as unbalanced loads (d) none of the above Ans: b 60. Delta/star transformer works satisfactorily when (a) load is balanced only (b) load is unbalanced only (c) on balanced as well as unbalanced loads (d) none of the above Ans: c 61. Buchholz's relay gives warning and protection against (a) electrical fault inside the transformer itself (b) electrical fault outside the transformer in outgoing feeder (c) for both outside and inside faults (d) none of the above Ans: a 62. The magnetising current of a transformer is usually small because it has (a) small air gap (b) large leakage flux (c) laminated silicon steel core (d) fewer rotating parts Ans: a Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 63. Which of the following does not change in an ordinary transformer ? (a) Frequency (b) Voltage (c) Current (d) Any of the above Ans: a 64. Which of the following properties is not necessarily desirable for the material for transformer core ? (a) Low hysteresis loss (b) High permeability (c) High thermal conductivity (d) Adequate mechanical strength Ans: c 65. The leakage flux in a transformer depends upon (a) load current (b) load current and voltage (c) load current, voltage and frequency (d) load current, voltage, frequency and power factor Ans: a 66. The path of the magnetic flux in transformer should have (a) high reluctance (b) low reactance (c) high resistance (d) low resistance Ans: b 67. Noise level test in a transformer is a (a) special test (b) routine test (c) type test (d) none of the above Ans: c 68. Which of the foJIowing is not a routine test on transformers ? Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) Core insulation voltage test (b) Impedance test (c) Radio interference test (d) Polarity test Ans: c 69. A transformer can have zero voltage regulation at (a) leading power factor (b) lagging power factor (c) unity power factor (d) zero power factor Ans: a 70. Helical coils can be used on (a) low voltage side of high kVA trans¬formers (b) high frequency transformers (c) high voltage side of small capacity transformers (d) high voltage side of high kVA rating transformers Ans: a 71. Harmonics in transformer result in (a) increased core losses (b) increased I2R losses (c) magnetic interference with communication circuits (d) all of the above Ans: d 72. The core used in high frequency transformer is usually (a) copper core (b) cost iron core (c) air core (d) mild steel core Ans: c 73. The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be (a) 6400 W (b) 1600 W Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) 800 W (d) 400 W Ans: d 1.74. The value of flux involved m the e.m.f. equation of a transformer is (a) average value (b) r.m.s. value (c) maximum value (d) instantaneous value Ans: c L.75. Silicon steel used in laminations mainly reduces (a) hysteresis loss (b) eddy current losses (c) copper losses (d) all of the above Ans: a 76. Which winding of the transformer has less cross-sectional area ? (a) Primary winding (b) Secondary winding (c) Low voltage winding (d) High voltage winding Ans: d 77. Power transformers are generally designed to have maximum efficiency around (a) no-load (b) half-load (c) near full-load (d) 10% overload Ans: c .78. Which of the following is the main advantage of an auto-transformer over a two winding transformer ? (a) Hysteresis losses are reduced (b) Saving in winding material (c) Copper losses are negligible (d) Eddy losses are totally eliminated Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: b 79. During short circuit test iron losses are negligible because (a) the current on secondary side is negligible (b) the voltage on secondary side does not vary (c) the voltage applied on primary side is low (d) full-load current is not supplied to the transformer Ans: c 80. Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in (a) short-circuiting of the secondaries (b) power factor of one of the trans¬formers is leading while that of the other lagging (c) transformers having higher copper losses will have negligible core losses (d) loading of the transformers not in proportion to their kVA ratings Ans: d 81. The changes in volume of transformer cooling oil due to variation of atmospheric temperature during day and night is taken care of by which part of transformer (a) Conservator (b) Breather (c) Bushings (d) Buchholz relay Ans: a 82. An ideal transformer is one which has (a) no losses and magnetic leakage (b) interleaved primary and secondary windings (c) a common core for its primary and secondary windings (d) core of stainless steel and winding of pure copper metal (e) none of the above Ans: a 83. When a given transformer is run at its rated voltage but reduced frequency, its (a) flux density remains unaffected (b) iron losses are reduced (c) core flux density is reduced Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) core flux density is increased Ans: d 84. In an actual transformer the iron loss remains practically constant from noload to fullload because (a) value of transformation ratio remains constant (b) permeability of transformer core remains constant (c) core flux remains practically constant (d) primary voltage remains constant (c) secondary voltage remains constant Ans: c 85. An ideal transformer will have maximum efficiency at a load such that (a) copper loss = iron loss (b) copper loss < iron loss (c) copper loss > iron loss (d) none of the above Ans: a 86. If the supply frequency to the transformer is increased,"the iron loss will (a) not change (b) decrease (c) increase (d) any of the above Ans: c 87. Negative voltage regulation is indicative that the load is (a) capacitive only (b) inductive only (c) inductive or resistive (d) none of the above Ans: a 88. Iron loss of a transformer can be measured by (a) low power factor wattmeter (b) unity power factor wattmeter (c) frequency meter (d) any type of wattmeter Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: a 89. When secondary of a current transformer is open-circuited its iron core will be (a) hot because of heavy iron losses taking place in it due to high flux density (b) hot because primary will carry heavy current (c) cool as there is no secondary current (d) none of above will happen Ans: a 90. The transformer laminations are insulated from each other by (a) mica strip (6) thin coat of varnish (c) paper (d) any of the above Ans: b 91. Which type of winding is used in 3phase shell-type transformer ? (a) Circular type (b) Sandwich type (c) Cylindrical type (d) Rectangular type Ans: b 92. During open circuit test of a transformer (a) primary is supplied rated voltage (b) primary is supplied full-load current (c) primary is supplied current at reduced voltage (d) primary is supplied rated kVA Ans: a 93. Open circuit test on transformers is conducted to determine (a) hysteresis losses (b) copper losses (c) core losses (d) eddy current losses Ans: c 94. Short circuit test on transformers is conducted to determine Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) hysteresis losses (b) copper losses (c) core losses (d) eddy current losses Ans: b 95. For the parallel operation of single phase transformers it is necessary that they should have (a) same efficiency (b) same polarity (c) same kVA rating (d) same number of turns on the secondary side. Ans: b 96. The transformer oil should have _____ volatility and _____ viscosity. (a) low,low (b) high,high (c) low,high (d) high,low Ans: a 97. The function of breather in a transformer is (a) to provide oxygen inside the tank (b) to cool the coils during reduced load (c) to cool the transformer oil (d) to arrest flow of moisture when outside air enters the transformer Ans: d 98. The secondary winding of which of the following transformers is always kept closed ? (a) Step-up transformer (b) Step-down transformer (c) Potential transformer (d) Current transformer Ans: d 99. The size of a transformer core will depend on (a) frequency (b) area of the core Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) flux density of the core material (d) (a) and (b) both Ans: d 100. N atural air coo ling is generally restricted for transformers up to (a) 1.5 MVA (b) 5 MVA (c) 15 MVA (d) 50 MVA Ans: a 101. A shell-type transformer has (a) high eddy current losses (b) reduced magnetic leakage (c) negligibly hysteresis losses (d) none of the above Ans: b 102. A transformer can have regulation closer to zero (a) on full-load (b) on overload (c) on leading power factor (d) on zero power factor Ans: c 103. A transformer transforms (a) voltage (b) current (c) current and voltage (d) power Ans: d 104. Which of the following is not the standard voltage for power supply in India ? (a) llkV (b) 33kV (c) 66 kV (d) 122 kV Ans: d Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 105. Reduction in core losses and increase in permeability are obtained with transformer employing (a) core built-up of laminations of cold rolled grain oriented steel (b) core built-up of laminations of hot rolled sheet (c) either of the above (d) none of the above Ans: a 106. In a power or distribution transformer about 10 per cent end turns are heavily insulated (a) to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns (b) to absorb the line surge voltage and save the winding of transformer from damage (c) to reflect the line surge and save the winding of a transformer from damage (d) none of the above Ans: a 107. For given applied voltage, with the increase in frequency of the applied voltage (a) eddy current loss will decrease (b) eddy current loss will increase (c) eddy current loss will remain unchanged (d) none of the above Ans: c 108. Losses which occur in rotating electric machines and do not occur in trans formers are (a) friction and windage losses (b) magnetic losses (c) hysteresis and eddy current losses (d) copper losses Ans: a 109. In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are (a) hysteresis and eddy current losses (b) friction and windage losses (c) copper losses Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) none of the above Ans: a 110. Which of the following statements regarding an idel single-phase transformer having a turn ratio of 1 : 2 and drawing a current of 10 A from 200 V A.C. supply is incorrect ? (a) Its secondary current is 5 A (b) Its secondary voltage is 400 V (c) Its rating is 2 kVA (d) Its secondary current is 20 A (e) It is a step-up transformer Ans: d 111 The secondary of a current transformer is always short-circuited under operating conditions because it (a) avoids core saturation and high voltage induction (b) is safe to human beings (c) protects the primary circuit (d) none of the above Ans: a 112. In a transformer the resistance between its primary and secondary should be (a) zero (b) 10 Q (c) 1000 Q (d) infinity Ans: d 113. A good voltage regulation of a transformer means (a) output voltage fluctuation from no load to full load is least (b) output voltage fluctuation with power factor is least (c) difference between primary and secondary voltage is least (d) difference between primary and secondary voltage is maximum Ans: a 114. For a transformer, operating at constant load current, maximum efficiency will occur at (a) 0.8 leading power factor Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) 0.8 lagging power factor (c) zero power factor (d) unity power factor Ans: d 115. Which of the following protection is normally not provided on small distribution transformers ? (a) Overfluxing protection (b) Buchholz relay (c) Overcurrent protection (d) All of the above Ans: b 116. Which of the following acts as a protection against high voltage surges due to lightning and switching ? (a) Horn gaps (b) Thermal overload relays (c) Breather (d) Conservator Ans: a 117. The efficiency of two identical transformers under load conditions can be determined by (a) short-circuit test (b) back-to-back test (c) open circuit test (d) any of the above Ans: b 118. Which of the following insulating materials can withstand the highest temperature safely ? (a) Cellulose (b) Asbestos (c) Mica (d) Glass fibre Ans: c 119. Which of the following parts of a transformer is visible from outside ? Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) Bushings (b) Core (c) Primary winding (d) Secondary winding Ans: a 120. The noise produced by a transformer is termed as (a) zoom (b) hum (c) ringing (d) buzz Ans: b 121. Which of the following loss in a transformer is zero even at full load ? (a) Core loss (b) Friction loss (c) Eddy current loss (d) Hysteresis loss Ans: b 122. Which of the following is the most likely source of harmonics in a transformer ? (a) poor insulation (b) Overload (c) loose connections (d) Core saturation Ans: d 123. If a transformer is continuously operated the maximum temperature rise will occur in (a) core (b) windings (c) tank (d) any of the above Ans: b 124. The hum in a transformer is mainly attributed to (a) load changes (b) oil in the transformer Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) magnetostriction (d) mechanical vibrations Ans: c 125. The maximum load that a power transformer can carry is limited by its (a) temperature rise (b) dielectric strength of oil (c) voltage ratio (d) copper loss Ans: c 126. The efficiency of a transformer, under heavy loads, is comparatively low because (a) copper loss becomes high in proportion to the output (b) iron loss is increased considerably (c) voltage drop both in primary and secondary becomes large (d) secondary output is much less as compared to primary input Ans: a 127. An open-circuit test on a transformer is conducted primarily to measure (a) insulation resistance (b) copper loss (c) core loss (d) total loss (e) efficiency (f) none of the above Ans: c 128. A no-load test is performed on a transformer to determine (a) core loss (b) copper loss (c) efficiency (d) magnetising current (e) magnetising current and loss Ans: e 129. The voltage transformation ratio of a transformer is equal to the ratio of (a) primary turns to secondary turns (b) secondary current to primary current Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) secondary induced e.m.f. to primary induced e.m.f. (d) secondary terminal voltage to primary applied voltage Ans: c 130. Part of the transformer which is most subject to damage from overheating is (a) iron core (b) copper winding (c) winding insulation (d) frame or case (e) transformer tank Ans: c 131. If a transformer is switched on to a voltage more than the rated voltage (a) its power factor will deteriorate (b) its power factor will increase (c) its power factor will remain unaffected (d) its power factor will be zero Ans: a 132. Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is (a) approximately equal to one (b) less than one (c) great than one (d) none of the above Ans: a 133. Minimum voltage regulation occurs when the power factor of the load is (a) unity (b) lagging (c) leading (d) zero Ans: c 134. In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of (a) less than 15 A (b) more than 15 A Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) 15 A (d) none of the above Ans: a 135. The efficiencies of transformers compared with that of electric motors of the same power are (a) about the same (6) much smaller (c) much higher (d) somewhat smaller (e) none of the above Ans: c 3. A. THREE PHASE INDUCTION MOTORS 1. Which of the following component is usually fabricated out of silicon steel ? (a) Bearings (b) Shaft (c) Statorcore (d) None of the above Ans: c 2. The frame of an induction motor is usually made of (a) silicon steel (b) cast iron (c) aluminium (d) bronze Ans: b 3. The shaft of an induction motor is made of (a) stiff (b) flexible (c) hollow (d) any of the above Ans: a 4. The shaft of an induction motor is made of (a) high speed steel (b) stainless steel (c) carbon steel (d) cast iron Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: c 5. In an induction motor, no-load the slip is generally (a) less than 1% (b) 1.5% (c) 2% (d) 4% Ans: a 6. In medium sized induction motors, the slip is generally around (a) 0.04% (b) 0.4% (c) 4% (d) 14% Ans: c 7. In squirrel cage induction motors, the rotor slots are usually given slight skew in order to (a) reduce windage losses (b) reduce eddy currents (c) reduce accumulation of dirt and dust (d) reduce magnetic hum Ans: d 8. In case the air gap in an induction motor is increased (a) the magnetising current of the rotor will decrease (b) the power factor will decrease (c) speed of motor will increase (d) the windage losses will increase Ans: b 9. Slip rings are usually made of (a) copper (b) carbon (c) phospor bronze (d) aluminium Ans: c 10. A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor e.m.f. will be (a) 200 Hz (b) 50 Hz (c) 2 Hz Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) 0.2 Hz Ans: c 11. In Ns is the synchronous speed and s the slip, then actual running speed of an induction motor will be (a) Ns (b) s.N, (c) (l-s)Ns (d) (Ns-l)s Ans: c The efficiency of an induction motor can be expected to be nearly (a) 60 to 90% (b) 80 to 90% (c) 95 to 98% (d) 99% Ans: b 13. The number of slip rings on a squirrel cage induction motor is usually (a) two (b) three (c) four (d) none Ans: d 14. The starting torque of a squirrel-cage induction motor is (a) low (b) negligible (c) same as full-load torque (d) slightly more than full-load torque Ans: a 15. A double squirrel-cage induction motor has (a) two rotors moving in oppsite direction (b) two parallel windings in stator (c) two parallel windings in rotor (d) two series windings in stator Ans: c 16. Star-delta starting of motors is not possible in case of (a) single phase motors (b) variable speed motors (c) low horse power motors Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) high speed motors Ans: a 17. The term 'cogging' is associated with (a) three phase transformers (b) compound generators (c) D.C. series motors (d) induction motors Ans: d 18. In case of the induction motors the torque is (a) inversely proportional to (Vslip) (b) directly proportional to (slip)2 (c) inversely proportional to slip (d) directly proportional to slip Ans: d 19. An induction motor with 1000 r.p.m. speed will have (a) 8 poles (b) 6 poles (c) 4 poles (d) 2 poles Ans: b 20. The good power factor of an induction motor can be achieved if the average flux density in the air gap is (a) absent (b) small (c) large (d) infinity Ans: b 21. An induction motor is identical to (a) D.C. compound motor (b) D.C. series motor (c) synchronous motor (d) asynchronous motor Ans: d 22. The injected e.m.f. in the rotor of induction motor must have (a) zero frequency (b) the same frequency as the slip fre-quency Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) the same phase as the rotor e.m.f. (d) high value for the satisfactory speed control Ans: b 23. Which of the following methods is easily applicable to control the speed of the squirrel-cage induction motor ? (a) By changing the number of stator poles (b) Rotor rheostat control (c) By operating two motors in cascade (d) By injecting e.m.f. in the rotor circuit Ans: a 24. The crawling in the induction motor is caused by (a) low voltage supply (b) high loads (c) harmonics develped in the motor (d) improper design of the machine (e) none of the above Ans: c 25. The auto-starters (using three auto transformers) can be used to start cage induction motor of the following type (a) star connected only (b) delta connected only (c) (a) and (b) both (d) none of the above Ans: c 26. The torque developed in the cage induction motor with autostarter is (a) k/torque with direct switching (6) K x torque with direct switching (c) K2 x torque with direct switching (d) k2/torque with direct switching Ans: c 27. When the equivalent circuit diagram of doouble squirrel-cage induction motor is constructed the two cages can be considered (a) in series (b) in parallel (c) in series-parallel (d) in parallel with stator Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 28. It is advisable to avoid line-starting of induction motor and use starter because (a) motor takes five to seven times its full load current (b) it will pick-up very high speed and may go out of step (c) it will run in reverse direction (d) starting torque is very high Ans: a 29. Stepless speed control of induction motor is possible by which of the following methods ? (a) e.m.f. injection in rotor eueuit (b) Changing the number of poles (c) Cascade operation (d) None of the above Ans: b 30. Rotor rheostat control method of speed control is used for (a) squirrel-cage induction motors only (b) slip ring induction motors only (c) both (a) and (b) (d) none of the above Ans: b 31. In the circle diagram for induction motor, the diameter of the circle represents (a) slip (b) rotor current (c) running torque (d) line voltage Ans: b 32. For which motor the speed can be controlled from rotor side ? (a) Squirrel-cage induction motor (b) Slip-ring induction motor (c) Both (a) and (b) (d) None of the above Ans: b 33. If any two phases for an induction motor are interchanged (a) the motor will run in reverse direction (b) the motor will run at reduced speed (c) the motor will not run (d) the motor will burn Ans: a Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 34. An induction motor is (a) self-starting with zero torque (b) self-starting with high torque (c) self-starting with low torque (d) non-self starting Ans: c 35. The maximum torque in an induction motor depends on (a) frequency (b) rotor inductive reactance (c) square of supply voltage (d) all of the above Ans: d 36. In three-phase squirrel-cage induction motors (a) rotor conductor ends are short-circuited through slip rings (b) rotor conductors are short-circuited through end rings (c) rotor conductors are kept open (d) rotor conductors are connected to insulation Ans: b 37. In a three-phase induction motor, the number of poles in the rotor winding is always (a) zero (b) more than the number of poles in stator (c) less than number of poles in stator (d) equal to number of poles in stator Ans: d 38. DOL starting of induction motors is usually restricted to (a) low horsepower motors (b) variable speed motors (c) high horsepower motors (d) high speed motors Ans: a 39. The speed of a squirrel-cage induction motor can be controlled by all of the following except (a) changing supply frequency (b) changing number of poles (c) changing winding resistance (d) reducing supply voltage Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 40. The 'crawling" in an induction motor is caused by (a) high loads (6) low voltage supply (c) improper design of machine (d) harmonics developed in the motor Ans: d 41. The power factor of an induction motor under no-load conditions will be closer to (a) 0.2 lagging (b) 0.2 leading (c) 0.5 leading (d) unity Ans: a 42. The 'cogging' of an induction motor can be avoided by (a) proper ventilation (b) using DOL starter (c) auto-transformer starter (d) having number of rotor slots more or less than the number of stator slots (not equal) Ans: d 43. If an induction motor with certain ratio of rotor to stator slots, runs at 1/7 of the normal speed, the phenomenon will be termed as (a) humming (b) hunting (c) crawling (d) cogging Ans: c 44. Slip of an induction motor is negative when (a) magnetic field and rotor rotate in opposite direction (b) rotor speed is less than the syn-chronous speed of the field and are in the same direction (c) rotor speed is more than the syn-chronous speed of the field and are in the same direction (d) none of the above Ans: c 45. Size of a high speed motor as compared to low speed motorfor the same H.P. will be (a) bigger (b) smaller (c) same Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) any of the above Ans: b 46. A 3-phase induction motor stator delta connected, is carrying full load and one of its fuses blows out. Then the motor (a) will continue running burning its one phase (b) will continue running burning its two phases (c) will stop and carry heavy current causing permanent damage to its winding (d) will continue running without any harm to the winding Ans: a 47. A 3-phase induction motor delta connected is carrying too heavy load and one of its fuses blows out. Then the motor (a) will continue running burning its one phase (b) will continue running burning its two phase (c) will stop and carry heavy current causing permanent damage to its winding (d) will continue running without any harm to the winding Ans: c 48. Low voltage at motor terminals is due to (a) inadequate motor wiring (b) poorely regulated power supply (c) any one of the above (d) none of the above Ans: c 49. In an induction motor the relationship between stator slots and rotor slots is that (a) stator slots are equal to rotor slots (b) stator slots are exact multiple of rotor slots (c) stator slots are not exact multiple of rotor slots (d) none of the above Ans: c 50. Slip ring motor is recommended where (a) speed control is required (6) frequent starting, stopping and reversing is required (c) high starting torque is needed (d) all above features are required Ans: d 51. As load on an induction motor goes on increasing (a) its power factor goes on decreasing Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) its power factor remains constant (c) its power factor goes on increasing even after full load (d) its power factor goes on increasing upto full load and then it falls again Ans: d 52. If a 3-phase supply is given to the stator and rotor is short circuited rotor will move (a) in the opposite direction as the direction of the rotating field (b) in the same direction as the direction of the field (c) in any direction depending upon phase squence of supply Ans: b 53. It is advisable to avoid line starting of induction motor and use starter because (a) it will run in reverse direction (b) it will pick up very high speed and may go out of step (c) motor takes five to seven times its fullload current (d) starting torque is very high Ans: c 54. The speed characteristics of an induction motor closely resemble the speedload characteristics of which of the following machines (a) D.C. series motor (b) D.C. shunt motor (c) universal motor (d) none of the above Ans: b 55. Which type of bearing is provided in small induction motors to support the rotor shaft ? (a) Ball bearings (b) Cast iron bearings (c) Bush bearings (d) None of the above Ans: a 56. A pump induction motor is switched on to a supply 30% lower than its rated voltage. The pump runs. What will eventually happen ? It will (a) stall after sometime (b) stall immediately (c) continue to run at lower speed without damage (d) get heated and subsequently get damaged Ans: d Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 57. 5 H.P., 50-Hz, 3-phase, 440 V, induction motors are available for the following r.p.m. Which motor will be the costliest ? (a) 730 r.p.m. (b) 960 r.p.m. (c) 1440 r.p.m. (d) 2880 r.p.m. Ans: a 58. A 3-phase slip ring motor has (a) double cage rotor (6) wound rotor (c) short-circuited rotor (d) any of the above Ans: b 59. The starting torque of a 3-phase squirrel cage induction motor is (a) twice the full load torque (b) 1.5 times the full load torque (c) equal to full load torque Ans: b 60. Short-circuit test on an induction motor cannot be used to determine (a) windage losses (b) copper losses (c) transformation ratio (d) power scale of circle diagram Ans: a 61. In a three-phase induction motor (a) iron losses in stator will be negligible as compared to that in rotor (6) iron losses in motor will be neg¬ligible as compared to that in rotor (c) iron losses in stator will be less than that in rotor (d) iron losses in stator will be more than that in rotor Ans: d 62. In case of 3-phase induction motors, plugging means (a) pulling the motor directly on line without a starter (b) locking of rotor due to harmonics (c) starting the motor on load which is more than the rated load (d) interchanging two supply phases for quick stopping Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: d 63. Which is of the following data is required to draw the circle diagram for an induction motor ? (a) Block rotor test only (b) No load test only (c) Block rotor test and no-load test (d) Block rotor test, no-load test and stator resistance test Ans: d 64. In three-phase induction motors sometimes copper bars are placed deep in the rotor to (a) improve starting torque (b) reduce copper losses (c) improve efficiency (d) improve power factor Ans: a 65. In a three-phase induction motor (a) power factor at starting is high as compared to that while running (b) power factor at starting is low as compared to that while running (c) power factor at starting in the same as that while running Ans: b 66. The vafcie of transformation ratio of an induction motor can be found by (a) open-circuit test only (b) short-circuit test only (c) stator resistance test (d) none of the above Ans: b 67. The power scale of circle diagram of an induction motor can be found from (a) stator resistance test (6) no-load test only (c) short-circuit test only (d) noue of the above Ans: c 68. The shape of the torque/slip curve of induction motor is (a) parabola (b) hyperbola (c) rectangular parabola (d) straigth line Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: c 69. A change of 4% of supply voltage to an induction motor will produce a change of appromimately (a) 4% in the rotor torque (b) 8% in the rotor torque (c) 12% in the rotor torque (d) 16% in the rotor torque Ans: d 70. The stating torque of the slip ring induction motor can be increased by adding (a) external inductance to the rotor (b) external resistance to the rotor (c) external capacitance to the rotor (d) both resistance and inductance to rotor Ans: b 71. A 500 kW, 3-phase, 440 volts, 50 Hz, A.C. induction motor has a speed of 960 r.p.m. on full load. The machine has 6 poles. The slip of the machine will be (a) 0.01 (b) 0.02 (c) 0.03 (d) 0.04 Ans: d 72. The complete circle diagram of induetion motor can be drawn with the help of data found from (a) noload test (6) blocked rotor test (c) stator resistance test (d) all of the above Ans: d 73. In the squirrel-cage induction motor the rotor slots are usually given slight skew (a) to reduce the magnetic hum and locking tendency of the rotor (b) to increase the tensile strength of the rotor bars (c) to ensure easy fabrication (d) none of the above Ans: a 74. The torque of a rotor in an induction motor under running condition is maximum (a) at the unit value of slip (b) at the zero value of slip Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) at the value of the slip which makes rotor reactance per phase equal to the resistance per phase (d) at the value of the slip which makes the rotor reactance half of the rotor Ans: c 75. What will happen if the relative speed between the rotating flux of stator and rotor of the induction motor is zero ? (a) The slip of the motor will be 5% (b) The rotor will not run (c) The rotor will run at very high speed (d) The torque produced will be very large Ans: b 76. The circle diagram for an induction motor cannot be used to determine (a) efficiency (b) power factor (c) frequency (d) output Ans: a 77. Blocked rotor test on induction motors is used to find out (a) leakage reactance (b) power factor on short circuit (c) short-circuit current under rated voltage (d) all of the above Ans: d 78. Lubricant used for ball bearing is usually (a) graphite (b) grease (c) mineral oil (d) molasses Ans: b 79. An induction motor can run at synchronous speed when (a) it is run on load (b) it is run in reverse direction (c) it is run on voltage higher than the rated voltage (d) e.m.f. is injected in the rotor circuit Ans: d 80. Which motor is preferred for use in mines where explosive gases exist ? (a) Air motor Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) Induction motor (c) D.C. shunt motor (d) Synchronous motor Ans: a 81. The torque developed by a 3-phase induction motor least depends on (a) rotor current (b) rotor power factor (c) rotor e.m.f. (d) shaft diameter Ans: d 82. In an induction motor if air-gap is increased (a) the power factor will be low (b) windage losses will be more (c) bearing friction will reduce (d) copper loss will reduce In an induction motor Ans: a 83. In induction motor, percentage slip depends on (a) supply frequency (b) supply voltage (c) copper losses in motor (d) none of the above Ans: c 84. When /?2 is tne rotor resistance, .X2 the rotor reactance at supply frequency and s the slip, then the condition for maximum torque under running condi-tions will be (a) sR2X2 = 1 (b) sR2 = X2 (c) R2 = sX2 id) R2 = s2X2 Ans: c 85. In case of a double cage induction motor, the inner cage has (a) high inductance arid low resistance (b) low inductance and high resistance (c) low inductance and low resistance (d) high inductance and high resis¬tance Ans: a 86. The low power factor of induction motor is due to (a) rotor leakage reactance Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) stator reactance (c) the reactive lagging magnetizing current necessary to generate the magnetic flux (d) all of the above Ans: d 87. Insertion of reactance in the rotor circuit (a) reduces starting torque as well as maximum torque (b) increases starting torque as well as maximum torque (c) increases starting torque but maxi-mum torque remains unchanged (d) increases starting torque but maxi-mum torque decreases Ans: a 88. Insertion of resistance in the rotcir of an induction motor to develop a given torque (a) decreases the rotor current (b) increases the rotor current (c) rotor current becomes zero (d) rotor current rernains same Ans: d 89. For driving high inertia loods best type of induction motor suggested is (a) slip ring type (b) squirrel cage type (c) any of the above (d) none of the above Ans: a 90. Temperature of the stator winding of a three phase induction motor is obtained by (a) resistance rise method (b) thermometer method (c) embedded temperature method (d) all above methods Ans: d 91. The purpose of using short-circuit gear is (a) to short circuit the rotor at slip rings (b) to short circuit the starting resis¬tances in the starter (c) to short circuit the stator phase of motor to form star (d) none of the above Ans: a 92. In a squirrel cage motor the induced e.m.f. is (a) dependent on the shaft loading (b) dependent on the number of slots Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) slip times the stand still e.m.f. induced in the rotor (d) none of the above Ans: c 93. Less maintenance troubles are experienced in case of (a) slip ring induction motor (6) squirrel cage induction motor (c) both (a) and (b) (d) none of the above Ans: b 94. A squirrel cage induction motor is not selected when (a) initial cost is the main consideration (b) maintenance cost is to be kept low (c) higher starting torque is the main consideration (d) all above considerations are involved Ans: c 95. Reduced voltage starter can be used with (a) slip ring motor only but not with squirrel cage induction motor (b) squirrel cage induction motor only but not with slip ring motor (c) squirrel cage as well as slip ring induction motor (d) none of the above Ans: c 96. Slip ring motor is preferred over squirrel cage induction motor where (a) high starting torque is required (b) load torque is heavy (c) heavy pull out torque is required (d) all of the above Ans: a 97. In a star-delta starter of an induction motor (a) resistance is inserted in the stator (b) reduced voltage is applied to the stator (c) resistance is inserted in the rotor (d) applied voltage per1 stator phase is 57.7% of the line voltage Ans: d 98. The torque of an induction motor is (a) directly proportional to slip (b) inversely proportional to slip (c) proportional to the square of the slip Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) none of the above Ans: a 99. The rotor of an induction motor runs at (a) synchronous speed (b) below synchronous speed (c) above synchronous speed (d) any of the above Ans: b 100. The starting torque of a three phase induction motor can be increased by (a) increasing slip (b) increasing current (c) both (a) and (b) (d) none of the above Ans: c 101. Insertion of resistance in the stator of an induction motor (a) increases the load torque (b) decreases the starting torque (c) increases the starting torque (d) none of the above Ans: b 3. B. SINGLE PHASE INDUCTION MOTORS 1. In a split phase motor, the running winding should have (a) high resistance and low inductance (b) low resistance and high inductance (c) high resistance as well as high inductance (d) low resistance as well as low inductiance Ans: b 2. If the capacitor of a single-phase motor is short-circuited (a) the motor will not start (b) the motor will run (c) the motor will run in reverse direction (d) the motor will run in the same direction at reduced r.p.m. Ans: a 3. In capacitor start single-phase motors (a) current in the starting winding leads the voltage Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) current in the starting winding lags the voltage (c) current in the starting winding is in phase with voltage in running winding (d) none of the above Ans: a 4. In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to (a) improve power factor (b) increase overload capacity (c) reduce fluctuations in torque (d) to improve torque Ans: a 5. In a capacitor start motor, the phase displacement between starting and running winding can be nearly (a) 10° (b) 30° (c) 60° (d) 90° Ans: d 6. In a split phase motor (a) the starting winding is connected through a centrifugal switch (b) the running winding is connected through a centrifugal switch (c) both starting and running windings are connected through a centrifugal switch (d) centrifugal switch is used to control supply voltage Ans: a 7. The rotor developed by a single-phase motor at starting is (a) more than i.he rated torque (b) rated torque (c) less than the rated torque (d) zero Ans: d 8. Which of the following motor will give relatively high starting torque ? (a) Capacitor start motor (b) Capacitor run motor (c) Split phase motor (d) Shaded pole motor Ans: a 9. Which of the following motor will have relatively higher power factor ? Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) Capacitor run motor (b) Shaded pole motor (c) Capacitor start motor (d) Split phase motor Ans: a 10. In a shaded pole motor, the shading coil usually consist of (a) a single turn of heavy wire which is in parallel with running winding (b) a single turn of heavy copper wire which is short-circuited and carries only induced current (c) a multilayer fine gauge copper wire in parallel with running winding (d) none of the above Ans: b 11. In a shaded pole single-phase motor, the revolving field is produced by the use of (a) inductor (b) capacitor (c) resistor (d) shading coils Ans: d 12. A centrifugal switch is used to dis- connect 'starting winding when motor has (a) run for about 1 minute (b) run for about 5 minutes (c) picked up about 50 to 70 per cent of rated speed (d) picked up about 10 to 25 per cent of rated speed Ans: c 13. If a particular application needs high speed and high starting torque, then which of the following motor will be preferred ? (a) Universal motor (b) Shaded pole type motor (c) Capacitor start motor (d) Capacitor start and run motor Ans: a 14. The value of starting capacitor of a fractional horse power motor will be (a) 100 uF (6) 200 uF (c) 300 uF (d) 400 uF Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 15. In repulsion motor direction of rotation of motor (a) is opposite to that of brush shift (b) is the same as that of brush shift (c) is independent of brush shift Ans: b 16. In a single phase motor the centrifugal switch (a) disconnects auxiliary winding of the motor (b) disconnects main winding of the motor (c) reconnects the main winding the motor (d) reconnects the auxiliary winding of the motor Ans: a 17. The running winding of a single phase motor on testing with meggar is found to be ground. Most probable location of the ground will be (a) at the end connections (b) at the end terminals (c) anywhere on the winding inside a slot (d) at the slot edge where coil enters or comes out of the slot Ans: d 18. A capacitor-start single phase induction motor is switched on to supply with its capacitor replaced by an inductor of equivalent reactance value. It will (a) start and then stop (b) start and run slowly (c) start and run at rated speed (d) not start at all Ans: d 19. Which of the following motors is used in mixies ? (a) Repulsion motor (b) Reluctance motor (c) Hysteresis motor (d) Universal motor Ans: d 20. Which of the following motors is inherently self starting ? (a) Split motor (b) Shaded-pole motor (c) Reluctance motor (d) None of these Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 21. The direction of rotation of an hysteresis motor is determined by (a) interchanging the supply leads (b) position of shaded pole with respect to main pole (c) retentivity of the rotor material (d) none of these Ans: b 22. Burning out of windings is due to (a) short circuited capacitor (b) capacitor value hiving changed (c) open circuiting of capacitor (d) none of the above Ans: a 23. Direction of rotation of a split phase motor can be reversed by reversing the connection of (a) running winding only (b) starting winding only (c) either (a) or (b) (d) both (a) and (b) Ans: c 24. Short-circuiter is used in (a) repulsion induction motor (b) repulsion motor (c) repulsion start induction run motor (d) none of the above Ans: c 25. The range of efficiency for shaded pole motors is (a) 95% to 99% (b) 80% to 90% (c) 50% to 75% (d) 5% to 35% Ans: d 26. In a capacitor start single-phase motor, when capacitor is replaced by a resistance (a) torque will increase (b) the motor will consume less power (c) motor will run in reverse direction (d) motor will continue to run in same direction Ans: d Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 27. The power factor of a single-phase induction motor is usually (a) lagging (b) always leading (c) unity (d) unity to 0.8 leading Ans: a 28. A shaded pole motor can be used for (a) toys (b) hair dryers (c) circulators (d) any of the above Ans: d 29. A hysteresis motor works on the principle of (a) hysteresis loss (b) magnetisation of rotor (c) eddy current loss (d) electromagnetic induction Ans: a 30. Which of the following motor will give the highest starting torque ? (a) D.C. shunt motor (b) Schrage motor (c) Repulsion start and induction run motor (d) Universal motor Ans: b 31. For which of the applications a reluctance motor is preferred ? (a) Electric shavers (b) Refrigerators (c) Signalling and timing devices (d) Lifts and hoists Ans: c 32. The motor used on small lathes is usually (a) universal motor (b) D.C. shunt motor (c) single-phase capacitor run motor (d) 3-phase synchronous motor Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 33. Which of the following motors is preferred for tape-recorders ? (a) Shaded pole motor (b) Hysteresis motor (c) Two value capacitor motor (d) Universal motor Ans: b 34. A single-phase induction motor is (a) inherently self-starting with high torque (b) inherently self-starting with low torque (c) inherently non-self-starting with low torque (d) inherently non-self-starting with high torque Ans: c 35. A schrage motor can run on (a) zero slip (b) negative slip (c) positive slip (d) all of the above Ans: d 36. A universal motor can run on (a) A.C. only (6) D.C. only (c) either A.C. or D.C. (d) none of the above Ans: c 37. Which of the following single-phase motors is suitable for timing and control purposes ? (a) Reluctance motor (b) Series motor (c) Repulsion motor (d) Universal motor Ans: a 38. Single phase induction motor usually operates on (a) 0.6 power factor lagging (b) 0.8 power factor lagging (c) 0.8 power factor leading (d) unity power factor Ans: a Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 39. In split-phase motor iauxiliary winding is of (a) thick wire placed at the bottom of the slots (b) thick wire placed at the top of the slots (c) thin wire placed at the top of the slots (d) thin wire placed at the bottom of the slots Ans: c 40. Which of the following motors will operate at high power factor ? (a) Shaped pole motor (b) Split phase motor (c) Capacitor start motor (d) Capacitor run motor Ans: d 41. In a two value capacitor motor, the capacitor used for running purposes is (a) air capacitor (b) paper spaced oilfilled type (c) ceramic type (d) a.c. electrolytic type Ans: b 42. Which of the following motors can be run on AC. as well as D.C. supply ? (a) Universal motor (b) Repulsion motor (c) Synchronous motor (d) Reluctance motor Ans: a 43. In A.C. series motor compensating winding is employed to (a) reduce the effects of armature reaction (b) increase the torque (c) reduce sparking at the brushes (d) none of the above Ans: c 44. Which of the following single-phase induction motors is generally used in time phonographs ? (a) Resistance start (b) Capacitor start capacitor run (c) Shaded pole (d) Universal Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 45. Which of the following motors has highest starting torque ? (a) Repulsion motor (b) Shaped pole motor (c) Capacitor-start motor (d) Split-phase motor Ans: c 46. The repulsion-start induction-run motor is used because of (a) good power factor (b) high efficiency (c) minimum cost (d) high starting torque Ans: d 47. In case of a shaded pole motor the direction of rotation of the motor is (a) from main pole to shaded pole (b) from shaded pole to main pole (c) either of the above depending on voltage (d) either of the above depending on power factor Ans: a 48. In case of high speed universal motor which of the following needs more attention ? (a) End play (b) Air gap (c) Insulation in rotor (d) Balancing of rotor Ans: d 49. The wattage rating for a ceiling fan motor will be in the range (a) 200 to 250 W (b) 250 to 500 W (c) 50 to 150 W (d) 10 to 20 W Ans: c 50. The wattage of motor for driving domestic sewing machine will be around (a) 100 to 150 W (b) 40 to 75 W (c) 10 to 30 W (d) 5 to 10 W Ans: a 51. Which of the following single-phase motors has relatively poor starting torque ? Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) Universal motor (b) Repulsion motor (c) Capacitor motor (d) All single phase motors have zero starting torque Ans: c 52. Which type of load is offered by cranes and hoists ? (a) Gradually varying load (b) Non-reversing, no-load start (c) Reversing, light start (d) Reversing, heavy start Ans: d 53. The speed of a universal motor is generally reduced by using (a) gear trains (b) V-belts (c) brakes (d) chains Ans: a 54. Which of the following motors can be used for unity power factor ? (a) Capacitor run motor (b) Shaded pole motor (c) Hysteresis motor (d) Schrage motor Ans: d 55. When a D.C. series motor is connected to A.C. supply, the power factor will be low because of (a) high inductance of field and armature circuits (b) induced current in rotor due to variations of flux (c) fine copper wire winding (d) none of the above Ans: a 56. The direction of rotation of universal motor can be reversed the by reversing the flow of current through (a) armature winding (b) field winding (c) either armature winding or field winding (d) none of the above Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 57. In which single-phase motor, the rotor has no teeth or winding ? (a) Split phase motor (b) Reluctance motor (c) Hysteresis motor (d) Universal motor Ans: c 58. Which motor is normally free from mechanical and magnetic vibrations ? (a) Split phase motor (b) Universal motor (c) Hysteresis motor (d) Shaded pole motor Ans: c 59. As hysteresis motors are free from mechanical and magnetic vibrations therefore these are considered as suitable for (a) fans (b) blowers (c) sound equipment (d) mixer grinders Ans: c 60. A reluctance motor (a) is self-starting (b) is constant speed motor (c) needs no D.C. excitation (d) all of the above Ans: d 61. In a hysteresis motor, the rotor must have (a) retentivity (b) resistivity (c) susceptibility (d) none of the above Ans: a 62. The rotor of a hysteresis motor is made of (a) aluminium (b) cast iron (c) chrome steel (d) copper Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 63. The electric motor used in portable drills is (a) capacitor run motor (b) hysteresis motor (c) universal motor (d) repulsion motor Ans: c 64. Which of the following applications always have some load whenever switched on ? (a) Vacuum cleaners (b) Fan motors (c) Pistol drills (d) All of the above Ans: c 65. The speed control of universal motor used for sewing machines is by (a) friction (b) varying the resistance (c) tapping the field (d) centrifugal mechanism Ans: b 66. Torque developed by a single phase induction motor at starting is (a) pulsating (b) uniform (c) none of the above (d) nil Ans: d 67. In split phase motor main winding is of (a) thin wire placed at the top of the slots (b) thin wire placed at the bottom of the slots (c) thick wire placed at the bottom of the slots (d) thick wire placed at the top of the" slots Ans: c 68. In repulsion motor, maximum torque is developed when (a) brush axis is at 45° electrical to the field axis (b) brush axis coincides with the field axis (c) brush axis is at 90° electrical to the field axis (d) none of the above Ans: a 69. If the centrifugal switch does not open at 70 to 80 percent of synchronous speed of Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS motor, it would result in (a) damage to the starting winding (b) damage to the centrifugal switch (c) overloading of running winding (d) none of the above Ans: a 70. Speed torque characteristic of a repulsion induction motor is similar to that of a D.C. (a) shunt motor (b) series motor (c) compound motor (d) separately excited motor Ans: c 71. In a ceilingfan employing capacitor run motor (a) secondary winding surrounds the primary winding (b) primary winding surrounds the secondary winding (c) both are usual arrangements (d) none of the above Ans: a 72. The shaded pole motor is used for (a) high starting torque (b) low starting torque (c) medium starting torque (d) very high starting torque Ans: b 73. The rotor slots, in an induction motor, are usually not quite parallel to the shaft because it (a) improves the efficiency (b) helps the rotor teeth to remain under the stator teeth (c) helps in reducing the tendency of the rotor teeth to remain under the stator teeth (d) improves the power factor Ans: c 74. The speed/load characteristics of a universal motor is same as that of (a) A.C. motor (b) D.C. shunt motor (c) D.C. series motor (d) none of the above Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 75. The purpose of stator winding in the compensated repulsion motor is to (a) provide mechanical balance (b) improve power factor and provide better speed regulation (c) prevent hunting in the motor (d) eliminate armature reaction Ans: b 76. Which of the following motors is used for unity power factor ? (a) Hysteresis motor (b) Schrage motor (c) Universal motor (d) Reluctance motor Ans: b 77. The motor used for the compressors is (a) d.c. series motor (b) shaded pole motor (c) capacitor-start capacitor-run motor (d) reluctance motor Ans: c 78. Which of the following motors is used in a situation where load increases with speed ? (a) Induction motor (b) Three-phase series motor (c) Schrage motor (d) Hysteresis motor Ans: b 79. In repulsion motor, zero torque is developed when (a) brush axis is 45° electrical to field axis (b) brush axis coincides with the field axis (c) brush axis is 90° electrical to field axis (d) both (b) and (c) Ans: d 80. Centrifugal switch disconnects the auxiliary winding of the motor at about ____ percent of synchronous speed (a) 30 to 40 (b) 70 to 80 (c) 80 to 90 (d) 100 Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 81. Starting winding of a single phase motor of a refrigerator is disconnected from the circuit by means of a (a) magnetic relay (b) thermal relay (c) centrifugal switch (d) none of the above Ans: a 82. If a single phase induction motor runs slower than normal, the most likely defect is (a) worn bearings (b) short-circuit in the winding (c) open-circuit in the winding (d) none of the above Ans: a 83. Which of the following motors is used in tape-recorders ? (a) Hysteresis motor (b) Reluctance motor (c) Capacitor-run motor (d) Universal motor Ans: a 84. Which of the following statements regarding two value capacitor motor is incorrect ? (a) It is a reversing motor (b) It is preferred to permanent-split single-value capacitor motor where frequent reversals are required (c) It has low starting as well as rush¬ing currents (d) It has high starting torque Ans: b 85. Two-value capacitor motor finds increased application as compressor motor in small home air-conditioners because (a) it is comparatively cheaper (b) it has almost non-destructible capacitor (c) it has low starting as well as running currents at relatively high power factor (d) it is quiet in operation Ans: c 86. If the centrifugal switch of a two-value capacitor motor using two capacitors fails to open then (a) motor will not come upto speed (b) motor will not carry the load Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) current drawn by the motor will be excessively high (d) electrolytic capacitor will, in all probability, suffer break down Ans: d 87. In a universal motor, the most common cause of brush sparking is (a) open armature winding (b) shorted armature winding (c) shorted field winding" (d) high commutator mica (e) all of the above Ans: e 88. If starting winding of a single-phase induction motor is left in the circuit, it will (a) run faster (b) spark at light loads (c) draw excessive current and overheat (d) run slower Ans: c 89. Most of the fractional horsepower motors have either (a) hard and annealed bearings (b) ball or roller bearings (c) soft and porous bearings (d) plain or sleeve bearings Ans: d 90. Which of the following statements regarding reluctance-start motor is incorrect ? (a) It is similar to reluctance motor (b) It is basically an induction motor and not a synchronous one (c) So far as its basic working principle is concerned, it is similar to shaded pole motor (d) the air-gap between rotor and salient poles is non- uniform Ans: a 91. To reverse the direction of rotation of acapacitor start motor while it is running we should (a) disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding (b) disconnect motor from supply and immediately reconnect it to supply with reversed connections of the main winding (c) reverse the direction of connection of the auxiliary winding and after motor comes to rest then connect auxiliary winding to the supply (d) reverse the direction of connections of the auxiliary winding and im-mediately connect it to supply Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: a 92. In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will (a) become unstable (b) draw excessive armature current and may burn out (c) fall out of synchronism and come to stand still (d) run as induction motor Ans: d 93. Which of the following motors has two separate windings on the motor ? (a) Repulsion motor (b) Repulsion induction motor (c) Repulsion start induction run motor (d) None of the above Ans: b 94. A shaded pole motor does not possess (a) centrifugal switch (b) capacitor (c) commutator (d) all of the above Ans: d 95. In a A.C. series motor armature coils are usually connected to commutator (a) through resistance (b) through reactances (c) through capacitors (d) solidly Ans: a 96. Which of the following statements regarding a reluctance motor is incorrect ? (a) It cannot be reversed, ordinarily (b) It requires no D.C. field excitation for its operation (c) It is nothing else but a single-phase, salient pole synchronous-induction motor (d) Its squirrel cage-rotor is of unsym-metrical magnetic construction in order to vary reluctance path bet¬ween stator and rotor Ans: a 97. A universal motor is one which (a) can be operated either on D.C. or A.C. supply at approximately the same speed and output (b) can be marketed internationally Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) runs at dangerously high speed on no-load Ans: a 98. A repulsion motor is equipped with (a) slip rings (b) commutator (c) both (a) and (b) (d) none of the above Ans: b 99. The capacitors used in single-phase capacitor motors have no (a) voltage rating (b) dielectric medium (c) polarity marking (d) definite value Ans: c 100. If a D.C. series motor is operated on A.C. supply, it will (a) spark excessively (b) have poor efficiency (c) have poor power factor (d) all of the above Ans: d 101. After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on (a) running winding (b) rotor winding (c) field winding (d) compensating winding Ans: a 102. Which of the following statements regarding repulsion-start induction motor is incorrect ? (a) It requires more maintenance of commutator and other mechanical devices (b) It makes quite a bit of noise on starting (c) In fractional horse power motors, it has replaced the capacitor motors (d) It is not easily reversed Ans: c 103. A.C. series motor as compared to D.C. series motor has (a) smaller brush width (b) less number of field turns Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) more number of armature turns (d) less air gap (e) all of the above Ans: e 104. Locked rotor current of a shaded pole motor is (a) equal to full load current (b) less than full load current (c) slightly more than full load current (d) several times the full load current Ans: c 105. Speed control of a universal motor is achieved by (a) varying field flux with tapped field windings (b) connecting rheostat in series (c) applying variable voltage by means of silicon controlled rectifier (d) applying variable voltage by means of variable auto-transformer (e) all of the above methods Ans: e 106. Hysteresis motor is particularly useful for high-quality record players and tape- recorders because (a) it revolves synchronously (b) it is not subject to any magnetic or mechanical vibrations (c) it can be easily manufactured in extremely small sizes of upto 1 W output (d) it develops hysteresis torque which is extremely steady both in amplitude and phase Ans: d 107. Which of the following statements regarding hysteresis motor is in incorrect ? (a) It is extremely sensitive to fluctuations in supply voltage (b) Its high starting torque is due to its high rotor hysteresis loss (c) It is extremely quiet in operation (d) It accelerates from rest to full-speed almost instantaneously Ans: a 108. Which of the following statements regarding single-phase induction motoris correct ? (a) It requires only one winding (b) It can rotate in one direction only (c) It is self-starting (d) It is not self-starting Ans: d Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 109. The starting winding of a single-phase motor is placed in (a) armature (b) field (c) rotor (d) stator Ans: d 110. The speed of a universal motor is usually reduced by using (a) gearing (b) belts (c) brakes (d) chains Ans: a 4. SYNCHRONOUS MOTORS 1. Synchronous motors are generally not self-starting because (a) the direction of rotation is not fixed (b) the direction of instantaneous torque reverses after half cycle (c) startes cannot be used on these machines (d) starting winding is not provided on the machines Ans: b 2. In case one phase of a three-phase synchronous motor is short-circuited the motor will (a) not start (b) run at 2/3 of synchronous speed (c) run with excessive vibrations (d) take less than the rated load Ans: a 3. A pony motor is basically a (a) small induction motor (b) D.C. series motor (c) D.C. shunt motor (d) double winding A.C./D.C. motor Ans: a 4. A synchronous motor can develop synchronous torque (a) when under loaded (b) while over-excited (c) only at synchronous speed Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) below or above synchronous speed Ans: c 5. A synchronous motor can be started by (a) pony motor (b) D.C. compound motor (c) providing damper winding (d) any of the above Ans: d 6. A three-phase synchronous motor will have (a) no slip-rings (b) one slip-ring (c) two slip-rings (d) three slip-rings Ans: c 7. Under which of the following conditions hunting of synchronous motor is likely to occur ? (a) Periodic variation of load (b) Over-excitation (c) Over-loading for long periods (d) Small and constant load Ans: a 8. When the excitation of an unloaded salient pole synchronous motor suddenly gets disconnected (a) the motor stops (b) it runs as a reluctance motor at the same speed (c) it runs as a reluctance motor at a lower speed (d) none of the above Ans: a 9. When V is the applied voltage, then the breakdown torque of a synchronous motor varies as (a) V (b) V312 (c) V2 (d) 1/V Ans: a 10. The power developed by a synchronous motor will be maximum when the load angle is (a) zero Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) 45° (c) 90° (d) 120° Ans: c 11. A synchronous motor can be used as a synchronous capacitor when it is (a) under-loaded (b) over-loaded (c) under-excited (d) over-excited Ans: d 12. A synchronous motor is running on a load with normal excitation. Now if the load on the motor is increased (a) power factor as well as armature current will decrease (b) power factor as well as armature current will increase (c) power factor will increase but armature current will decrease (d) power factor will decrease and armature current will increase Ans: d 13. Mostly, synchronous motors are of (a) alternator type machines (6) induction type machines (c) salient pole type machines (d) smooth cylindrical type machines Ans: c 14. The synchronous motor is not inherently self-starting because (a) the force required to accelerate the rotor to the synchronous speed in an instant is absent (b) the starting device to accelerate the rotor to near synchronous speed is absent (c) a rotating magnetic field does not have enough poles (d) the rotating magnetic field is produced by only 50 Hz frequency currents Ans: a 15. As the load is applied to a synchronous motor, the motor takes more armature current because (a) the increased load has to take more current (b) the rotor by shifting its phase backward causes motor to take more current (c) the back e.m.f. decreases causing an increase in motor current (d) the rotor strengthens the rotating field casuing more motor current Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 16. Synchronous motor always runs at (a) the synchronous speed (b) less than synchronous speed (c) more than synchronous speed (d) none of the above Ans: a 17. An over-excited synchronous motor takes (a) leading current (b) lagging current (c) both (a) and (b) (d) none of the above Ans: a 18. The working of a synchronous motor is similar to (a) gear train arrangement (b) transmission of mechancial power by shaft (c) distribution transformer (d) turbine (e) none of the above Ans: b 19. The minimum armature current of the synchronous motor corresponds to operation at (a) zero power factor leading (b) unity power factor (c) 0.707 power factor lagging (d) 0.707 power factor leading Ans: b 20. In a synchronous motor, the magnitude of stator back e.m.f. £& depends on (a) d.c. excitation only (b) speed of the motor (c) load on the motor (d) both the speed and rotor flux Ans: a 21. If load (or torque) angle of a 4-pole synchronous motor is 6° electrical, its value in mechanical degrees is (a) 2 (b) 3 (c) 4 (d) 6 Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 22. For V-curves for a synchronous motor the graph is drawn between (a) field current and armature current (b) terminal voltage and load factor (c) power factor and field current (d) armature current and power factor Ans: a 23. The back e.m.f. of a synchronous motor depends on (a) speed (b) load (c) load angle (d) all of the above Ans: c 24. A synchronous motor can operate at (a) lagging power factor only (6) leading power factor only (c) unity power factor only (d) lagging, leading and unity power factors Ans: d 25. In a synchronous motor which loss varies with load ? (a) Windage loss (b) Bearing friction loss (c) Copper loss (d) Core loss Ans: c 26. A synchronous motor can be made self starting by providing (a) damper winding on rotor poles (b) damper winding on stator (c) damper winding on stator as well as rotor poles (d) none of the above Ans: d 27. The oscillations in a synchronous motor can be damped out by (a) maintaining constant excitation (b) running the motor on leading power factors (c) providing damper bars in the rotor pole faces (d) oscillations cannot be damped Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 28. The shaft of synchronous motor is made of (a) mild steel (b) chrome steel (c) alnico (d) stainless steel Ans: a 29. When the field of a synchronous motor is under-excited, the power factor will be (a) leading (b) lagging (c) unity (d) zero Ans: b 30. The speed regulation of a synchronous motor is always (a) 1% (b) 0.5% (c) positive (d) zero Ans: d 31. The percentage slip in case of a synchronous motor is (a) 1% (b) 100% (c) 0.5% (d) zero Ans: d 32. The operating speed of a synchronous motor can be changed to new fixed value by (a) changing the load (b) changing the supply voltage (c) changing frequency (d) using brakes Ans: c 33. A synchronous motor will always stop when (a) supply voltage fluctuates (b) load in motor varies (c) excitation winding gets disconnected (d) supply voltage frequency changes Ans: c 34. riunting in a synchronous motor takes place Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) when supply voltage fluctuates (b) when load varies (c) when power factor is unity (d) motor is under loaded Ans: b 35. When load on an over-excited or under excited synchronous*motor is increased, rate of change of its armature current as compared with that of power factor is (a) more (b) less (c) equal (d) twice Ans: b 36. The rotor copper losses, in a synchronous motor, are met by (a) d.c. source (b) armature input (c) motor input (d) supply lines Ans: a 37. The maximum power developed in a synchronous motor occurs at a coupling angle of (a) 30° (b) 60° (c) 90° (d) 180° Ans: c 38. When the stator windings are connected in such a fashion that the number of poles are made half, the speed of the rotor of a synchronous motor (a) remains same as the original value (b) decreases to half the original value (c) tends to becomes zero (d) increases to two times the original value Ans: d 39. In which of the following motors the stator and rotor magnetic field rotate at the same speed ? (a) Universal motor (b) Synchronous motor (c) Induction motor (d) Reluctance motor Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: b 40. Synchronsizingpower of a synchronous machine is (a) direcly proportional to the synchronous reactance (6) inversely proportional to the synchronous reactance (a) equal to the synchronous reactance (d) none of the above Ans: b 41. Synchronous motors are (a) not-self starting (b) self-starting (c) essentially self-starting (d) none of the above Ans: a 42. The standard full-load power factor ratings for synchronous motors are (a) zero or 0.8 leading (b) unity or 0.8 lagging (c) unity or 0.8 leading (d) unity or zero Ans: c 43. A synchronous motor running with normal excitation adjusts to load increases essentially by increase in (a) back e.m.f. (b) armature current (c) power factor (d) torque angle Ans: b 44. A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because (a) synchronous motor has no slip (b) stator supply is not required to produce magnetic field (c) mechanical load on the rotor remains constant (d) synchronous motor has large airgap Ans: b 45. A synchronous motor working at leading power factor can be used as (a) voltage booster (b) phase advancer Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) noise generator (d) mechanical synchronizer Ans: b 46. Slip rings are usually made of (a) carbon or graphite (b) brass or steel (c) silver or gold (d) copper or aluminium Ans: b 47. An over excited synchronous motor is used for (a) fluctuating loads (b) variable speed loads (c) low torque loads (d) power factor corrections Ans: d 48. When the voltage applied to a synchronous motor is increased, which of the following will reduce ? (a) Stator flux (b) Pull in torque (c) Both (a) and (b) (d) None of the above Ans: d 51. The efficiency of a properly designed synchronous motor will usually fall in range (a) 60 to 70% (6) 75 to 80% (c) 85 to 95% (d) 99 to 99.5% Ans: c 52. To limit the operating temperature an electrical machine should have proper (a) voltage rating (b) current rating (c) power factor (d) speed Ans: b 53. Slip-rings in a synchronous motor carry (a) direct current (b) alternating current Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) no current (d) all of the above Ans: a 54. A synchronous machine with large air gap has (a) a higher value of stability limit (6) a small value of inherent regulation (c) a higher synchronizing power which makes the machine less sensitive to load variations (d) all of the above Ans: d 55. The armature current of the synchronous motor has higher values for (a) high excitation only (b) low excitation only (c) both (a) and (b) (d) none of the above Ans: c 56. In a synchronous motor running with fixed excitation, when the load is increased three times, its torque angle becomes approximately (a) one-third (b) twice (c) thrice (d) six times (e) nine times Ans: c 57. The angle between the rotating stator flux and rotor poles is called _____ angle. (a) torque (b) obtuse (c) synchronizing (d) power factor Ans: a 58. Which of the following methods is used to start a synchronous motor ? (a) Damper winding (b) Star-delta starter (c) Damper winding in conjunction with star-delta starter (d) Resistance starter in the armature circuit Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 59. When the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop (a) inductor motor torque (b) induction generator torque (c) synchronous motor torque (d) d.c. motor toque (e) none of the above Ans: b 60. An important advantage of a synchronous motor over wound round induction motor is that (a) its power factor may be varied at will (b) its speed is independent of supply frequency (c) its speed may be controlled more easily (d) none of the above Ans: a 61. The mechanical displacement of the rotor with respect to the stator, in polyphase multipolar synchronous motors running at full load, is of the order of (a) zero degree (b) two degrees (c) five degrees (d) ten degrees Ans: c 62. Power factor of a synchronous motor is unity when (a) the armature current is maximum (b) the armature current is minimum (c) the armature current is zero (d) none of the above Ans: b 63. Change of D.C. excitation of a synchronous motor changes (a) applied voltage of the motor (b) motor speed (c) power factor of power drawn by the motor (d) any of the above (e) all of the above Ans: c 64. While starting a synchronous motor by induction motor action, field winding is Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS usually (a) connected to D.C. supply (b) short-circuited by low resistance (c) kept open-circuited (d) none of the above Ans: b 65. Which of the following motors will be used in electric clocks ? (a) D.C. shunt motor (b) D.C. series motor (c) A.C. induction motor (d) A.C. synchronous motor Ans: d 66. If in a synchronous motor, driving mechanical load and drawing current at lagging power factor from constant voltage supply, its field excitation is increased, then its power factor (a) become more (b) become less (c) remain constant (d) none of the above Ans: b 67. A synchronous motor installed at the receiving end substation operates with such an excitation that it takes power at lagging power factor. Now if the applied voltage of the synchronous motor goes down, the power factor of the synchronous motor will (a) remain same (b) go down (c) improve (d) none of the above Ans: c 68. While starting a salient pole synchronous motor by induction motor action and connecting field discharge resistance across field, starting and accelerting torque is produced by (a) induction motor torque in field winding (b) induction motor torque in damper winding (c) eddy current and hysteresis torque in pole faces (d) reHetance motor torque due to saliency of the rotor (e) all of the above methods Ans: e Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 69. Armature of a synchronous machine is (a) of reducing number of slip rings on the rotor (b) armature is associated with large power as compared to the field circuits (c) of difficulty of providing high voltage insulation on rotor (d) all of the above reasons Ans: d 70. If excitation of a synchronous motor running with a constant load is decreased from its normal value, ignoring effects of armature reaction, it leads to (a) increase in both armature current and power factor angle (b) increase in back e.m.f. but decrease in armature current (c) increase in both armature current and power factor which is lagging (d) increase in torque angle but decrease in back e.m.f. Ans: a 71. When a 3-phase synchronous generator is supplying a zero power factor lagging load, the armature field affects the main field in the following way (a) augments it directly (b) directly opposes it (c) cross-magnetises it (d) none of the above Ans: b 72. Stability of a synchronous machine (a) decreases with increase in its excitation (b) increases with increase in its excitation (c) remains unaffected with increase in excitation (d) any of the above Ans: b 73. The power factor of a synchronous motor is better than that of induction motor because (a) stator supply is relieved of responsibility of producing magnetic field (b) mechanical load on the motor can be adjusted (c) synchronous motor runs at synchronous speed (d) synchronous motor has large air gap Ans: a 74. If in a synchronous motor, driving a given mechanical load and drawing current at a leading power factor from constant voltage supply its field excitation is increased, its power factor Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) will become more (b) will become less (c) will remain unchanged (d) none of the above. Ans: b 75. A synchronous motor is running with normal excitation. When the load is increased, the armature current drawn by it increases because (a) speed of the motor is reduced (b) power factor is decreased (c) Eb (back e.m.f.) becomes less than V (applied voltage) (d) Er (net resultant voltage) in armature is increased (e) none of the above Ans: d 76. If one-phase of a 3-phase synchronous motor is short-circuited, motor (a) will refuse to start (b) will overheat in spots (c) will not come upto speed (d) will fail to pull into step Ans: a 77. If the field circuit of an unloaded salientpole synchronous motor gets suddenly open- circuited, then (a) it runs at a slower speed (b) the motor stops (c) it continues to run at the same speed (d) it runs at a very high speed Ans: b 78. In which of the following motors the stator and rotor fields rotate simultaneously ? (a) D.C. motor (b) Reluctance motor (c) Universal motor (d) Synchronous motor (e) Induction motor Ans: d 79. The speed of a synchronous motor (a) increases as the load increases (b) decreases as the load decreases (c) always remains constant Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) none of the above Ans: c 80. A rotory converter can also be run as a (a) d.c. shunt motor (b) d.c. series motor (c) d.c. compound motor (d) induction motor (e) synchronous motor Ans: e 81. The maximum speed variation in a 3-phase synchronous motor is (a) 10 per cent (b) 6 per cent (c) 4 per cent (d) 2. per cent (e) zero Ans: e 82. Which of the following resistances can be measured by conducting insulation resistance test on a synchronous motor ? (a) Phase to phase winding resistance (b) Stator winding to earthed frame (c) Rotor winding to earthed shaft (d) All of the above Ans: d 83. Due to which of the following reasons a synchronous motor fails to pull into synchronism after applying D.C. field current ? (a) High field current (b) Low short circuit ratio (c) High core losses (d) Low field current Ans: d 84. In a synchronous motor, the maximum power developed depends on all of the following except (a) rotor excitation (b) maximum value of coupling angle (c) direction of rotation (d) supply voltage Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 85. In a 3-phase synchronous motor, the negative phase sequence exists when the motor is (a) supplied with unbalanced voltage (b) under-loaded (c) over-loaded (d) none of the above Ans: a 86. In a synchronous motor, damper windings are provided on (a) stator frame (b) rotor shaft (c) pole faces (d) none of the above Ans: c 87. The induced e.m.f. in a synchronous motor working on leading power factor will be (a) more than the supply voltage (b) less than the supply voltage (c) equal to the supply voltage Ans: a 88. The effect of increasing the load on a synchronous motor running with normal excitation is to (a) decrease both armature current and power factor (6) decrease armature current but increase power factor (c) increase armature current but decrease power factor (d) increase both its armature current and power factor Ans: c 89. The net armature voltage of a synchronous motor is equal to the (a) vector sum of Eb and V (b) arithmetic sum of Eb and V (c) arithmetic difference of Eb and V (d) vector difference of Eh and V Ans: d 90. The ratio of starting torque to running torque in a synchronous motor is (a) zero (b) one (c) two (d) infinity Ans: a Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 91. In a synchronous motor, the magnitude of stator back e.m.f. Eb depends on (a) load on the motor (b) d.c. excitation only (c) both the speed and rotor flux (d) none of the above Ans: b 92. A 3-phase synchronous motor is running clockwise. If the direction of its field current is reversed (a) the motor will stop (b) the motor continue to run in the same direction (c) the winding of the motor will burn (d) the motor will run in the reverse direction (e) none of the above Ans: b 93. The magnitude of field flux in a 3-phase synchronous motor (a) remains constant at all loads (b) varies with speed (c) varies with the load (d) varies with power factor Ans: a 94. The torque angle, in a synchronous motor, is the angle between (a) the supply voltage and the back e.m.f. (b) magnetising current and back e.m.f. (c) the rotating stator flux and rotor poles (d) none of the above Ans: c 95. Hunting in a synchronous motor cannot be due to (a) windage friction (b) variable load (c) variable frequency (d) variable supply voltage Ans: a 96. By which of the following methods the constant speed of a synchronous motor can be changed to new fixed value ? (a) By changing the supply frequency (b) By interchanging any two phases (c) By changing the applied voltage Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) By changing the load. Ans: a 97. In a synchronous motor, V-curves represent relation between (a) armature current and field current (b) power factor and speed (c) field current and speed (d) field current and power factor Ans: a 98. In a 3-phase, 4-pole, 50 Hz synchronous motor, the frequency, pole number and load torque all are halved. The motor speed will be (a) 3000 r.p.m. (b) 1500 r.p.m. (c) 750 r.p.m. (d) none of the above Ans: b 99. A synchronous motor connected to infinite bus-bars has at constant full load, 100% excitation and unity power fac tor. On changing the excitation only, the armature current will have (a) no change of power factor (b) lagging power factor with over-excitation (c) leading power factor with under-excitation (d) leading power factor with over-excitation Ans: d 100. Which of the following motors is non-self starting ? (a) D.C. series motor (b) synchronous motor (c) Squirrel cage induction motor (d) Wound round induction motor Ans: b 101. In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then (a) the motor is said to be fully loaded (b) the torque generated is maximum (c) the excitation is said to be zero per cent (d) the excitation is said to be hundred per cent Ans: d 102. In a synchronous motor, the damping winding is generally used to Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) prevent hunting and provide the starting torque (b) reduce the eddy currents (c) provide starting torque only (d) reduce noise level (e) none of the above Ans: a 103. If the field of a synchronous motor is underexcited, the power factor will be (a) zero (b) unity (c) lagging (d) leading Ans: c 104. The back e.m.f. in the stator of a synchronous motor depends on (a) number of poles (b) flux density (c) rotor speed (d) rotor excitation (e) none of the above Ans: d 105. The maximum value of torque that a synchronous motor can develop without losing its synchronism, is known as (a) slip torque (b) pull-out torque (c) breaking torque (d) synchronising torque Ans: d 106. In a synchronous motor, the armature current has large values for (a) high excitation only (b) low excitation only (c) both high and low excitation (d) none of the above Ans: c 107. Which of the following losses, in a synchronous motor, does not vary with load? (a) Windage loss (b) Copper losses (c) Any of the above (d) None of the above Ans: a Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 108. The size of a synchronous motor decreases with the increase in (a) flux density (b) horse power rating (c) speed (d) all of the above Ans: a 109. Which of the following losses is not dissipated by the stator core surface in a synchronous motor ? (a) Eddy current losses in the conductors (b) Iron losses in the stator (c) Copper losses in the slot portion of the conductors (d) Windage losses (e) None of the above Ans: d 110. The duration of sudden snort-circuit test on a synchronous motor is usually about (a) one hour (b) one minute (c) one second (d) none of the above Ans: c 111. The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as (a) pull-up torque (b) pull-in torque (c) pull-out torque (d) none of the above Ans: b 112. A synchronous machine with low value of short-circuit ratio has (a) lower stability limit (6) high stability limit (c) good speed regulation (d) good voltage regulation (e) none of the above Ans: a 113. The construction of a synchronous motor resembles (a) a series motor Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) an induction motor (c) an alternator (d) a rotary converter Ans: c 114. If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will (a) stop (b) run as induction motor (c) function as static condenser (d) burn with dense smoke Ans: a 115 For power factor correction, synchronous motors operate at (a) no-load and greatly over-excited fields (b) no-load and under-excited fields (c) normal load with minimum excitation (d) normal load with zero excitation Ans: a 116. The maximum torque which a synchronous motor will develop at rest for any angular position of the rotor, at rated stator supply voltage and frequency, is known as (a) locked-rotor torque (b) synchronous torque (c) pull up torque (d) reluctance torque Ans: a 117. Exciters of synchronous machines are (a) d.c. shunt machines (b) d.c. series machines (c) d.c. compound machines (d) any of the above Ans: a 118. The coupling angle or load angle of synchronous motor is defined as the angle between the (a) rotor and stator teeth (b) rotor and the stator poles of opposite polarity (c) rotor and the stator poles of the same polarity (d) none of the above Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 119. If the synchronous motor, properly synchronised to the supply is running on no load and is having negligible loss then (a) the stator current will be zero (b) the stator current will be very small (c) the stator current will be very high (d) the back e.m.f. will be more than the supply voltage (e) none of the above Ans: a 120 The armature current of the synchronous motor (a) has large values for low excitation i niy (b) has large values for high excitation only (c) has large values for low and high excitation (d) any of the above Ans: c 121. The maximum power developed in a synchronous motor will depend on (a) the rotor excitation only (b) the supply voltage only (c) the rotor excitation and supply volt-age both (d) the rotor excitation, supply voltage and maximum value of coupling angle (90°) (e) none of the above Ans: d 122. A synchronous motor which works on a leading power factor and does not drive a mechanical load is called as (a) static condenser (b) condenser (c) synchronous condenser (d) none of the above Ans: c 123. A synchronous motor develops maximum power when load angle is (a) 45° (b) 60° (c) 90° (d) 120° Ans: c 124. In a synchronous motor, the breakdown torque is (a) directly proportional to applied voltage Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) directly proportional to the square of the applied voltage (c) inversely proportional to applied voltage (d) none of the above Ans: a 5. A. TRANSMISSION AND DISTRIBUTION 1. By which of the following systems electric power may be transmitted ? (a) Overhead system (b) Underground system (c) Both (a) and (b) (d) None of the above Ans: c 2 are the conductors, which connect the consumer's terminals to the distribution (a) Distributors (b) Service mains (c) Feeders (d) None of the above Ans: b 3. The underground system cannot be operated above (a) 440 V (b) 11 kV (c) 33 kV (d) 66 kV Ans: d 4. Overhead system can be designed for operation upto (a) 11 kV (b) 33 kV (c) 66 kV (d) 400 kV Ans: c 5. If variable part of annual cost on account of interest and depreciation on the capital outlay is equal to the annual cost of electrical energy wasted in the conductors, the total annual cost will be minimum and the corresponding size of conductor will be most economical. This statement is known as (a) Kelvin's law (b) Ohm's law Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) Kirchhoffs law (d) Faraday's law (e) none of the above Ans: a 6. The wooden poles well impregnated with creosite oil or any preservative compound have life (a) from 2 to 5 years (b) 10 to 15 years (c) 25 to 30 years (d) 60 to 70 years Ans: c 7. Which of the following materials is not used for transmission and distribution of electrical power ? (a) Copper (b) Aluminium (c) Steel (d) Tungsten Ans: d 8. Galvanised steel wire is generally used as (a) stay wire (b) earth wire (c) structural components (d) all of the above Ans: d 9. The usual spans with R.C.C. poles are (a) 40—50 metres (b) 60—100 metres (c) 80—100 metres (d) 300—500 metres Ans: c 10. The corona is considerably affected by which of the following ? (a) Size of the conductor (b) Shape of the conductor (c) Surface condition of the conductor (d) All of the above Ans: d 11. Which of the following are the constants of the transmission lines ? Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) Resistance (b) Inductance (c) Capacitance (d) All of the above Ans: d 12. 310 km line is considered as (a) a long line (b) a medium line (c) a short line (d) any of the above Ans: a 13. The phenomenon qf rise in voltage at the receiving end of the open-circuited or lightly loaded line is called the (a) Seeback effect (b) Ferranti effect (c) Raman effect (d) none of the above Ans: b 14. The square root of the ratio of line impedance and shunt admittance is called the (a) surge impedance of the line (b) conductance of the line (c) regulation of the line (d) none of the above Ans: a 15. Which of the following is the demerit of a 'constant voltage transmission system' ? (a) Increase of short-circuit current of the system (b) Availability of steady voltage at all loads at the line terminals (c) Possibility of better protection for the line due to possible use of higher terminal reactances (d) Improvement of power factor at times of moderate and heavy loads (e) Possibility of carrying increased power for a given conductor size in case of long- distance heavy power transmission Ans: a 16. Low voltage cables are meant for use up to (a)l.lkV (b)3.3kV Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c)6.6kV (d)llkV Ans: e 17. The operating voltage of high voltage cables is upto (a)l.lkV (b)3.3kV (c)6.6kV (d)llkV Ans: d 18. The operating voltage of supertension cables is upto (a) 3.3 kV (b) 6.6 kV (c) 11 kV (d) 33 kV Ans: d 19. The operating voltage of extra high tension cables is upto (a) 6.6 kV (b) 11 kV (c) 33 kV (d) 66 kV (e) 132 kV Ans: d 20. Which of the following methods is used for laying of underground cables ? (a) Direct laying (b) Draw-in-system (c) Solid system (d) All of the above Ans: d 21. Which of the following is the source of heat generation in the cables ? (a) Dielectric losses in cable insulation (b) losses in the conductor (c) Losses in the metallic sheathings and armourings (d) All of the above Ans: 22. Due to which of the following reasons the cables should not be operated too hot ? (a) The oil may loose its viscosity and it may start drawing off from higher levels (b) Expansion of the oil may cause the sheath to burst Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) Unequal expansion may create voids in the insulation which will lead to ionization (d) The thermal instability may rise due to the rapid increase of dielectric losses with temperature (e) All of the above Ans: e 23. Which of the following D.C. distribution system is the simplest and lowest in first cost ? (a) Radial system (b) Ring system (c) Inter-connected system (d) None of the above Ans: a 24. A booster is a (a) series wound generator (b) shunt wound generator (c) synchronous generator (d) none of the above Ans: a 25. Besides a method of trial and error, which of the following methods is employed for solution of network problems in interconnected system ? (a) Circulating current method (b) Thevenin's theorem (c) Superposition of currents (d) Direct application of Kirehhoffs laws (e) All of the above Ans: e 26. Which of the following faults is most likely to occur in cables ? (a) Cross or short-circuit fault (b) Open circuit fault (c) Breakdown of cable insulation (d) All of the above Ans: d 27. The cause of damage to the lead sheath of a cable is (a) crystallisation of the lead through vibration (b) chemical action on the lead when buried in the earth (c) mechanical damage Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) all of the above Ans: d 28. The voltage of the single phase supply to residential consumers is (a) 110 V (b) 210 V (c) 230 V (d) 400 V Ans: c 29. Most of the high voltage transmission lines in India are (a) underground (b) overhead (c) either of the above (d) none of the above Ans: b 30. The distributors for residential areas are (a) single phase (b) three-phase three wire (c) three-phase four wire (d) none of the above Ans: c 31. The conductors of the overhead lines are (a) solid (b) stranded (c) both solid and stranded (d) none of the above Ans: b 32. High voltage transmission lines use (a) suspension insulators (b) pin insulators (c) both (a) and (b) (d) none of the above Ans: a 33. Multicore cables generally use (a) square conductors (b) circular conductors (c) rectangular conductors (d) sector-shaped conductors Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (e) none of the above Ans: d 34. Distribution lines in India generally use (a) wooden poles (b) R.C.C. poles (c) steel towers (d) none of the above Ans: b 35. The material commonly used for insulation in high voltage cables is (a) lead (b) paper (c) rubber (d) none of the above Ans: b 36. The loads on distributors systems are generally (a) balanced (b) unbalanced (c) either of the above (d) none of the above Ans: b 37. The power factor of industrial loads is generally (a) unity (b) lagging (c) leading (d) zero Ans: b 38. Overhead lines generally use (a) copper conductors (b) all aluminium conductors (c) A.C.S.R. conductors (d) none of these Ans: c 39. In transmission lines the cross-arms are made of (a) copper (b) wood (c) R.C.C. (d) steel Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS Ans: d 40. The material generally used for armour of high voltage cables is (a) aluminium (b) steel (c) brass (d) copper Ans: b 41. Transmission line insulators are made of (a) glass (b) porcelain (c) iron (d) P.V.C. Ans: b 42. The material commonly used for sheaths of underground cables is (a) lead (b) rubber (c) copper (d) iron Ans: a 43. The minimum clearance between the ground and a 220 kV line is about (a) 4.3 m (b) 5.5 m (c) 7.0 m (d) 10.5 m Ans: c 44. The spacing between phase conductors of a 220 kV line is approximately equal to (a) 2 m (b) 3.5 m (c) 6 m (d) 8.5 m Ans: c 45. Large industrial consumers are supplied electrical energy at (a) 400 V (b) 11 kV (c) 66 kV (d) 400 kV Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 46. In a D.C. 3-wire distribution system, balancer fields are cross-connected in order to (a) boost the generated voltage (b) balance loads on both sides of the neutral (c) make both machine^ run as unloaded motors (d) equalize voltages on the positive and negative outers Ans: d 47. In a D.C. 3-wire distributor using balancers and having unequal loads on the two sides (a) both balancers run as generators (b) both balancers run as motors (c) balancer connected to lightly- loaded side runs as a motor (d) balancer connected to heavily- loaded side runs as a motor Ans: c 48. Transmitted power remaining the same, if supply voltage of a D.C. 2-wire feeder is increased 100 percent, saving in copper is (a) 25 percent (b) 50 percent (c) 75 percent (d) 100 percent Ans: b 49. A uniformly-loaded D.C. distributor is fed at both ends with equal voltages. As compared to a similar distributor fed at one end only, the drop at the middle point is (a) one-fourth (b) one-third (c) one-half (d) twice (e) none of the above Ans: a 50. As compared to a 2-wire D.C. distributor, a 3-wire distributor with same maximum voltage to earth uses only (a) 31.25 percent of copper (b) 33.3 percent of copper (c) 66.7 percent of copper (d) 125 percent of copper Ans: a 51. Which of the following is usually not the generating voltage ? (a) 6.6 kV (b) 8.8 kV Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) 11 kV (d) 13.2 kV Ans: b 52. For an overhead line, the surge impedance is taken as (a) 20-30 ohms (b) 70—80 ohms (c) 100—200 ohms (d) 500—1000 ohms (e) none of the above Ans: c 53. The presence of ozone due to corona is harmful because it (a) reduces power factor (b) corrodes the material (c) gives odour (d) transfer energy to the ground (e) none of the above Ans: b 54. A feeder, in a transmission system, feeds power to (a) distributors (b) generating stations (c) service mains (d) all of the above Ans: a 55. The power transmitted will be maximum when (a) corona losses are minimum (b) reactance is high (c) sending end voltage is more (d) receiving end voltage is more Ans: c 56. A 3-phase 4 wire system is commonly used on (a) primary transmission (b) secondary transmission (c) primary distribution (d) secondary distribution Ans: d 57. Which of the following materials is used for overhead transmission lines ? (a) Steel cored aluminium Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) Galvanised steel (c) Cadmium copper (d) Any of the above Ans: d 58. Which of the following is not a constituent for making porcelain insulators ? (a) Quartz (b) Kaolin (c) Felspar (d) Silica Ans: d 59. There is a greater possibility of occurence of corona during (a) dry weather (b) winter (c) summer heat (d) humid weather (e) none of the above Ans: d 60. Which of the following relays is used on long transmission lines ? (a) Impedance relay (b) Mho's relay (c) Reactance relay (d) None of the above Ans: b 61. The steel used in steel cored conductors is usually (a) alloy steel (b) stainless steel (c) mild steel (d) high speed steel (e) all of the above Ans: c 62. Which of the following distribution systems is more reliable ? (a) Radial system (b) Tree system (c) Ring main system (d) All are equally reliable Ans: c 63. Which of the following characteristics should the line supports for transmission lines Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS possess ? (a) Low cost (b) High mechanical strength (c) Longer life (d) All of the above Ans: d 64. Transmission voltage of llkV is normally used for distances upto (a) 20—25 km (b) 40—50 km (c) 60—70 km (d) 80—100 km Ans: a 65. Which of the following regulations is considered best? (a) 50% (b) 20% (c) 10% (d) 2% Ans: d 66. Skin effect is proportional to (a) (conductor diameter) (b) (conductor diameter) (c) (conductor diameter) (d) (conductor diameter) (e) none of the above Ans: c 67. A conductor, due to sag between two supports, takes the form of (a) semi-circle (b) triangle (c) ellipse (d) catenary Ans: d 68. In AC.S.R. conductors, the insulation between aluminium and steel conductors is (a) insulin (b) bitumen (c) varnish (d) no insulation is required Ans: d Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 69. Which of the followingbus-bar schemes has the lowest cost ? (a) Ring bus-bar scheme (b) Single bus-bar scheme (c) Breaker and a half scheme (d) Main and transfer scheme Ans: b 70. Owing to skin effect (a) current flows through the half cross-section of the conductor (b) portion of the conductor near the surface carries more current and core of the conductor carries less current (c) portion of the conductor near the surface carries less current and core of the conductor carries more current (d) any of the above (e) none of the above Ans: b 71. By which of the following methods string efficiency can be improved ? (a) Using a guard ring (b) Grading the insulator (c) Using long cross arm (d) Any of the above (e) None of the above Ans: d 72. In aluminium conductors, steel core is provided to (a) compensate for skin effect (b) neutralise proximity effect (c) reduce line inductance (d) increase the tensile strength Ans: d 73. By which of the following a bus-bar is rated ? (a) Current only (b) Current and voltage (c) Current, voltage and frequency (d) Current, voltage, frequency and short time current Ans: d 74. A circuit is disconnected by isolators when (a) line is energized (b) there is no current in the line (c) line is on full load Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) circuit breaker is not open Ans: b 75. For which of the following equipment current rating is not necessary ? (a) Circuit breakers (b) Isolators (c) Load break switch (d) Circuit breakers and load break switches Ans: b 76. In a substation the following equipment is not installed (a) exciters (b) series capacitors (c) shunt reactors (d) voltatre transformers Ans: a 77. jCorona usually occurs when the electrostatic stress in air around the conductor exceeds (a) 6.6 kV (r.m.s. value)/cm (b) 11 kV (r.m.s. value)/cm (c) 22 kV (maximum value)/cm (d) 30 kV (maximum v^lue)/cm Ans: d 78. The voltage drop, for constant voltage transmission is compensated by installing (a) inductors (b) capacitors (c) synchronous motors (d) all of above (e) none of the above Ans: c 79. The use of strain type insulators is made where the conductors are (a) dead ended (b) at intermediate anchor towers (c) any of the above (d) none of the above Ans: c 80. The current drawn by the line due to corona losses is (a) non-sinusoidal (b) sinusoidal Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) triangular (d) square Ans: a 81. Pin type insulators are generally not used for voltages beyond (a) 1 kV (b) 11 kV (c) 22 kV (d) 33 kV Ans: d 82. Aluminium has a specific gravity of (a) 1.5 (b) 2.7 (c) 4.2 (d) 7.8 Ans: b 83. For transmission of power over a distance of 200 km, the transmission voltage should be (a) 132 kV (b) 66 kV (c) 33 kV (d) 11 kV Ans: a 84. For aluminium, as compared to copper, all the following factors have higher values except (a) specific volume (6) electrical conductivity (c) co-efficient of linear expansion (d) resistance per unit length for same cross-section Ans: b 85. Which of the following equipment, for regulating the voltage in distribution feeder, will be most economical ? (a) Static condenser (b) Synchronous condenser (c) Tap changing transformer (d) Booster transformer Ans: d 86. In a tap changing transformer, the tappings are provided on Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) primary winding (b) secondary winding (c) high voltage winding (d) any of the above Ans: b 87. Constant voltage transmission entails the following disadvantage (a) large conductor area is required for same power transmission (b) short-circuit current of the system is increased (c) either of the above (d) none of the above Ans: b 88. On which of the following factors skin effect depends ? (a) Frequency of the current (b) Size of the conductor (c) Resistivity of the conductor material (d) All of the above Ans: d 89. The effect of corona can be detected by (a) presence of zone detected by odour (b) hissing sound (c) faint luminous glow of bluish colour (d) all of the above Ans: d 90. For transmission of power over a distance of 500 km, the transmission voltage should be in the range (a) 150 to 220 kV (b) 100 to 120 kV (c) 60 to 100 kV (d) 20 to 50 kV Ans: a 91. In the analysis of which of the following lines shunt capacitance is neglected ? (a) Short transmission lines (b) Medium transmission lines (c) Long transmission lines (d) Medium as well as long transmission lines Ans: a 92. When the interconnector between two stations has large reactance Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) the transfer of power will take place with voltage fluctuation and noise (b) the transfer of power will take place with least loss (c) the stations will fall out of step because of large angular displacement between the stations (d) none of the above Ans: c 93. The frequency of voltage generated, in case of generators, can be increased by (a) using reactors (b) increasing the load (c) adjusting the governor (d) reducing the terminal voltage (e) none of the above Ans: c 94. When an alternator connected to the bus-bar is shut down the bus-bar voltage will (a) fall (b) rise (c) remain unchanged (d) none of the above Ans: c 95. The angular displacement between two interconnected stations is mainly due to (a) armature reactance of both alternators (b) reactance of the interconnector (c) synchronous reactance of both the alternators (d) all of the above Ans: a 96. Electro-mechanical voltage regulators are generally used in (a) reactors (b) generators (c) transformers (d) all of the above Ans: b 97. Series capacitors on transmission lines are of little use when the load VAR requirement is (a) large (b) small (b) fluctuating (d) any of the above Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 98. The voltage regulation in magnetic amplifier type voltage regulator is effected by (a) electromagnetic induction (b) varying the resistance (c) varying the reactance (d) variable transformer Ans: c 99. When a conductor carries more current on the surface as compared to core, it is due to (a) permeability variation (b) corona (c) skin effect (d) unsymmetrical fault (e) none of the above Ans: c 100. The following system is not generally used (a) 1-phase 3 wire (b) 1-phase 4 wire (c) 3-phase 3 wire (d) 3-phase 4 wire Ans: a 101. The skin effect of a conductor will reduce as the (a) resistivity of conductor material increases (b) permeability of conductor material increases (c) diameter increases (d) frequency increases Ans: a 102. When a live conductor of public electric supply breaks down and touches the earth which of the following will happen ? (a) Current will flow to earth (b) Supply voltage will drop (c) Supply voltage will increase (d) No current will flow in the conductor (e) None of the above Ans: a 5. B. DC GENERATORS 1. The insulating material for a cable should have (a) low cost Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) high dielectric strength (c) high mechanical strength (d) all of the above Ans: d 2. Which of the following protects a cable against mechanical injury ? (a) Bedding (b) Sheath (c) Armouring (d) None of the above Ans: c 3. Which of the following insulation is used in cables ? (a) Varnished cambric (b) Rubber (c) Paper (d) Any of the above Ans: d 4. Empire tape is (a) varnished cambric (b) vulcanised rubber (c) impregnated paper (d) none of the above Ans: a 5. The thickness of the layer of insulation on the conductor, in cables, depends upon (a) reactive power (b) power factor (c) voltage (d) current carrying capacity Ans: c 6. The bedding on a cable consists of (a) hessian cloth (b) jute (c) any of the above (d) none of the above Ans: c 7. The insulating material for cables should (a) be acid proof (b) be non-inflammable Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) be non-hygroscopic (d) have all above properties Ans: d 8. In a cable immediately above metallic sheath _____ is provided. (a) earthing connection (b) bedding (c) armouring (d) none of the above Ans: b 9. The current carrying capacity of cables in D.C. is more thanthat in A.C. mainly due to (a) absence of harmonics (b) non-existence of any stability limit (c) smaller dielectric loss (d) absence of ripples (e) none of the above Ans: c 10. In case of three core flexible cable the colour of the neutral is (a) blue (b) black (c) brown (d) none of the above Ans: a 11 cables are used for 132 kV lines. (a) High tension (b) Super tension (c) Extra high tension (d) Extra super voltage Ans: d 12. Conduit pipes are normally used to protect _____ cables. (a) unsheathed cables (b) armoured (c) PVC sheathed cables (d) all of the above Ans: a 13. The minimum dielectric stress in a cable is at (a) armour (b) bedding Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) conductor surface (d) lead sheath Ans: d 14. In single core cables armouring is not done to (a) avoid excessive sheath losses (b) make it flexible (c) either of the above (d) none of the above Ans: a 15. Dielectric strength of rubber is around (a) 5 kV/mm (b) 15 kV/mm (c) 30 kV/mm (d) 200 kV/mm Ans: c 16. Low tension cables are generally used upto (a) 200 V (b) 500 V (c) 700 V (d) 1000 V Ans: d 17. In a cable, the maximum stress under operating conditions is at (a) insulation layer (b) sheath (c) armour (d) conductor surface Ans: d 18. High tension cables are generally used upto (a) 11kV (b) 33kV (c) 66 kV (d) 132 kV Ans: a 19. The surge resistance of cable is (a) 5 ohms (b) 20 ohms (c) 50 ohms Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) 100 ohms Ans: c 20. PVC stands for (a) polyvinyl chloride (b) post varnish conductor (c) pressed and varnished cloth (d) positive voltage conductor (e) none of the above Ans: a In the cables, the location of fault is usually found out by comparing (a) the resistance of the conductor (b) the inductance of conductors (c) the capacitances of insulated conductors (d) all above parameters Ans: c 22. In capacitance grading of cables we use a ______ dielectric. (a) composite (b) porous (c) homogeneous (d) hygroscopic Ans: a 23. Pressure cables are generally not used beyond (a) 11 kV (b) 33 kV (c) 66 kV (d) 132 kV Ans: c 24. The material for armouring on cable is usually (a) steel tape (b) galvanised steel wire (c) any of the above (d) none of the above Ans: c 25. Cables, generally used beyond 66 kV are (a) oil filled (b) S.L. type (c) belted Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (d) armoured Ans: a 26. The relative permittivity of rubber is (a) between 2 and 3 (b) between 5 and 6 (c) between 8 and 10 (d) between 12 and 14 Ans: a 27. Solid type cables are considered unreliable beyond 66 kV because (a) insulation may melt due to higher temperature (b) skin effect dominates on the conduc¬tor (c) of corona loss between conductor and sheath material (d) there is a danger of breakdown of insulation due to the presence of voids Ans: d 28. If the length of a cable is doubled, its capacitance (a) becomes one-fourth (b) becomes one-half (c) becomes double (d) remains unchanged Ans: c 29. In cables the charging current (a) lags the voltage by 90° (b) leads the voltage by 90° (c) lags the voltage by 180° (d) leads the voltage by 180° Ans: b 30. A certain cable has an insulation of relative permittivity 4. If the insulation is replaced by one of relative permittivity 2, the capacitance of the cable will become (a) one half (6) double (c) four times (d) none of the above Ans: a 31. If a cable of homogeneous insulation has a maximum stress of 10 kV/mm, then the dielectric strength of insulation should be (a) 5 kV/mm (b) 10 kV/mm Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (a) 15 kV/mm (d) 30 kV/mm Ans: b 32. In the cables, sheaths are used to (a) prevent the moisture from entering the cable (b) provide enough strength (e) provide proper insulation (d) none of the above Ans: a 33. The intersheaths in the cables are used to (a) minimize the stress (b) avoid the requirement of good insulation (c) provide proper stress distribution (d) none of the above Ans: c 34. The electrostatic stress in underground cables is (a) same at the conductor and the sheath (b) minimum at the conductor and maximum at the sheath (c) maximum at the conductor and minimum at the sheath (d) zero at the conductor as well as on the sheath (e) none of the above Ans: c 35. The breakdown of insulation of the cable can be avoided economically by the use of (a) inter-sheaths (b) insulating materials with different dielectric constants (c) both (a) and (b) (d) none of the above Ans: c 36. The insulation of the cable decreases with (a) the increase in length of the insulation (b) the decrease in the length of the insulation (c) either (a) or (b) (d) none of the above Ans: a 37. A cable carrying alternating current has (a) hysteresis losses only (b) hysteresis and leakage losses only Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (c) hysteresis, leakage and copper losses only (d) hysteresis, leakage, copper and friction losses Ans: b 38. In a cable the voltage stress is maximum at (a) sheath (6) insulator (e) surface of the conductor (d) core of the conductor Ans: d 39. Capacitance grading of cable implies (a) use of dielectrics of different permeabilities (b) grading according to capacitance of cables per km length (c) cables using single dielectric in different concentrations (d) capacitance required to be introduced at different lengths to counter the effect of inductance (e) none of the above Ans: a 40. Underground cables are laid at sufficient depth (a) to minimise temperature stresses (b) to avoid being unearthed easily due to removal of soil (c) to minimise the effect of shocks and vibrations due to gassing vehicles, etc. (d) for all of the above reasons Ans: c 41. The advantage of cables over overhead transmission lines is (a) easy maintenance (b) low cost (c) can be used in congested areas (d) can be used in high voltage circuits Ans: c 42. The thickness of metallic shielding on cables is usually (a) 0.04 mm (b) 0.2 to 0.4 mm (e) 3 to 5 mm (d) 40 to 60 mm Ans: a 43. Cables for 220 kV lines are invariably (a) mica insulated Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) paper insulated (c) compressed oil or compressed gas insulated (d) rubber insulated (e) none of the above Ans: c 44. Is a cable is to be designed for use on 1000 kV, which insulation would you prefer ? (a) Polyvinyle chloride (b) Vulcanised rubber (c) Impregnated paper (d) Compressed SFe gas (e) none of the above Ans: d 45. If a power cable and a communication cable are to run parallel the minimum distance between the two, to avoid interference, should be (a) 2 cm (b) 10 cm (c) 50 cm (d) 400 cm Ans: c 46. Copper as conductor for cables is used as (a) annealed (b) hardened and tempered (c) hard drawn (d) alloy with chromium Ans: a 47. The insulating material should have (a) low permittivity (b) high resistivity (c) high dielectric strength (d) all of the above Ans: d 48. The advantage of oil filled cables is (a) more perfect impregnation (b) smaller overall size (c) no ionisation, oxidation and formation of voids (d) all of the above Ans: d Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS 49. The disadvantage with paper as insulating material is (a) it is hygroscopic (6) it has high capacitance (c) it is an organic material (d) none of the above Ans: a 50. The breakdown voltage of a cable depends on (a) presence of moisture (b) working temperature (c) time of application of the voltage (d) all of the above Ans: d 51. It is difficult to maintain oil filled cables. (a) Yes (b) No Ans: a 51. In capacitance grading a homogeneous dielectric is used. (a) Yes (b) No Ans: b 52. In congested areas where excavation is expensive and inconvenient 'draw in system' of laying of underground cables is often adopted. (a) Yes (b) No Ans: a 53. Natural rubber is obtained from milky sap of tropical trees. (a) Yes (b) No Ans: a 54. Rubber is most commonly used insulation in cables. (a) Yes (b) No Ans: a 55. Polyethylene has very poor dielectric and ageing properties. (a) Yes Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS (b) No Ans: b 56. The metallic sheath may be made of lead or lead alloy or of aluminium. (a) Yes (b) No Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR CONTROL SYSTEMS OBJECTIVE TYPE QUESTIONS 1. In an open loop control system (a) Output is independent of control input (b) Output is dependent on control input (c) Only system parameters have effect on the control output (d) None of the above Ans: a 2. For open control system which of the following statements is incorrect ? (a) Less expensive (b) Recalibration is not required for maintaining the required quality of the output (c) Construction is simple and maintenance easy (d) Errors are caused by disturbances Ans: b 3. A control system in which the control action is somehow dependent on the output is known as (a) Closed loop system (b) Semiclosed loop system (c) Open system (d) None of the above Ans: a 4. In closed loop control system, with positive value of feedback gain the overall gain of the system will (a) decrease (b) increase (c) be unaffected (d) any of the above Ans: a 5. Which of the following is an open loop control system ? (a) Field controlled D.C. motor (b) Ward leonard control (c) Metadyne (d) Stroboscope Ans: a 6. Which of the following statements is not necessarily correct for open control system ? (a) Input command is the sole factor responsible for providing the control action (b) Presence of non-linearities causes malfunctioning (c) Less expensive (d) Generally free from problems of non-linearities Ans: b 7. In open loop system (a) the control action depends on the size of the system (b) the control action depends on system variables (c) the control action depends on the input signal (d) the control action is independent of the output Ans: d 8 has tendency to oscillate. (a) Open loop system (b) Closed loop system (c) Both (a) and (b) (d) Neither (a) nor (b) Ans: b 9. A good control system has all the following features except (a) good stability (b) slow response (c) good accuracy (d) sufficient power handling capacity Ans: b 10. A car is running at a constant speed of 50 km/h, which of the following is the feedback element for the driver ? (a) Clutch (b) Eyes (c) Needle of the speedometer (d) Steering wheel (e) None of the above Ans: c 11. The initial response when the output is not equal to input is called (a) Transient response (b) Error response (c) Dynamic response (d) Either of the above Ans: a 12. A control system working under unknown random actions is called (a) computer control system (b) digital data system (c) stochastic control system (d) adaptive control system Ans: c 13. An automatic toaster is a ______ loop control system. (a) open (b) closed (c) partially closed (d) any of the above Ans: a 14. Any externally introduced signal affecting the controlled output is called a (a) feedback (b) stimulus (c) signal (d) gain control Ans: b 15. A closed loop system is distinguished from open loop system by which of the following ? (a) Servomechanism (b) Feedback (c) Output pattern (d) Input pattern Ans: b 16 is a part of the human temperature control system. (a) Digestive system (b) Perspiration system (c) Ear (d) Leg movement Ans: b 17. By which of the following the control action is determined when a man walks along a path ? (a) Brain (b) Hands (c) Legs (d) Eyes Ans: d 18 is a closed loop system. (a) Auto-pilot for an aircraft (6) Direct current generator (c) Car starter (d) Electric switch Ans: a 19. Which of the following devices are commonly used as error detectors in instruments ? (a) Vernistats (b) Microsyns (c) Resolvers (d) Any of the above Ans: d 20. Which of the following should be done to make an unstable system stable ? (a) The gain of the system should be decreased (b) The gain of the system should be increased (c) The number of poles to the loop transfer function should be increased (d) The number of zeros to the loop transfer function should be increased Ans: b 21 increases the steady state accuracy. (a) Integrator (b) Differentiator (c) Phase lead compensator (d) Phase lag compensator Ans: a 22. A.C. servomotor resembles (a) two phase induction motor (b) Three phase induction motor (c) direct current series motor (d) universal motor Ans: a 23. As a result of introduction of negative feedback which of the following will not decrease ? (a) Band width (b) Overall gain (c) Distortion (d) Instability Ans: a 24. Regenerative feedback implies feedback with (a) oscillations (b) step input (c) negative sign (d) positive sign Ans: d 25. The output of a feedback control system must be a function of (a) reference and output (b) reference and input (e) input and feedback signal (d) output and feedback signal Ans: a 26 is an open loop control system. (a) Ward Leonard control (b) Field controlled D.C. motor (c) Stroboscope (d) Metadyne Ans: b 27. A control system with excessive noise, is likely to suffer from (a) saturation in amplifying stages (b) loss of gain (c) vibrations (d) oscillations Ans: a 28. Zero initial condition for a system means (a) input reference signal is zero (b) zero stored energy (c) ne initial movement of moving parts (d) system is at rest and no energy is stored in any of its components Ans: d 29. Transfer function of a system is used to calculate which of the following ? (a) The order of the system (b) The time constant (c) The output for any given input (d) The steady state gain Ans: c 30. The band width, in a feedback amplifier. (a) remains unaffected (b) decreases by the same amount as the gain increase (c) increases by the sane saaaajajt as the gain decrease (d) decreases by the same amount as the gain decrease Ans: c 31. On which of the following factors does the sensitivity of a closed loop system to gain changes and load disturbances depend ? (a) Frequency (b) Loop gain (c) Forward gain (d) All of the above Ans: d 32. The transient response, with feedback system, (a) rises slowly (b) rises quickly (c) decays slowly (d) decays quickly Ans: d 33. The second derivative input signals modify which of the following ? (a) The time constant of the system (b) Damping of the system (c) The gain of the system (d) The time constant and suppress the oscillations (e) None of the above Ans: d 34. Which of the following statements is correct for any closed loop system ? (a) All the co-efficients can have zero value (6) All the co-efficients are always non-zero (c) Only one of the static error co-efficients has a finite non-zero value (d) None of the above Ans: c 35. Which of the following statements is correct for a system with gain margin close to unity or a phase margin close to zero ? (a) The system is relatively stable (b) The system is highly stable (c) The system is highly oscillatory (d) None of the above Ans: c 36. Due to which of the following reasons excessive bond width in control systems should be avoided ? (a) It leads to slow speed of response (b) It leads to low relative stability (c) Noise is proportional to band width (d) None of the above Ans: c 37. In a stable control system backlash can cause which of the following ? (a) Underdamping (b) Overdamping (c) Poor stability at reduced values of open loop gain (d) Low-level oscillations Ans: d 38. In an automatic control system which of the following elements is not used ? (a) Error detector (b) Final control element (c) Sensor (d) Oscillator Ans: d 39. In a control system the output of the controller is given to (a) final control element (b) amplifier (c) comparator (d) sensor (e) none of the above Ans: a 40. A controller, essentially, is a (a) sensor (b) clipper (c) comparator (d) amplifier Ans: c 41. Which of the following is the input to a controller ? (a) Servo signal (b) Desired variable value (c) Error signal (d) Sensed signal Ans: 42. The on-off controller is a _____ system. (a) digital (b) linear (c) non-linear (d) discontinuous Ans: 43. The capacitance, in force-current analogy, is analogous to (a) momentum (b) velocity (c) displacement (d) mass Ans: d 44. The temperature, under thermal and electrical system analogy, is considered analogous to (a) voltage (b) current (c) capacitance (d) charge (e) none of the above Ans: a 45. In electrical-pneumatic system analogy the current is considered analogous to (a) velocity (b) pressure (c) air flow (d) air flow rate Ans: d 46. In liquid level and electrical system analogy, voltage is considered analogous to (a) head (b) liquid flow (c) liquid flow rate (d) none of the above Ans: a 47. The viscous friction co-efficient, in force-voltage analogy, is analogous to (a) charge (b) resistance (c) reciprocal of inductance (d) reciprocal of conductance (e) none of the above Ans: b 48. In force-voltage analogy, velocity is analogous to (a) current (b) charge (c) inductance (d) capacitance Ans: a 49. In thermal-electrical analogy charge is considered analogous to (a) heat flow (b) reciprocal of heat flow (c) reciprocal of temperature (d) temperature (e) none of the above Ans: d 50. Mass, in force-voltage analogy, is analogous to (a) charge (b) current (c) inductance (d) resistance Ans: c 51. The transient response of a system is mainly due to (a) inertia forces (b) internal forces (c) stored energy (d) friction Ans: c 52 signal will become zero when the feedback signal and reference signs are equal. (a) Input (b) Actuating (c) Feedback (d) Reference Ans: b 53. A signal other than the reference input that tends to affect the value of controlled variable is known as (a) disturbance (b) command (c) control element (d) reference input Ans: a 54. The transfer function is applicable to which of the following ? (a) Linear and time-in variant systems (b) Linear and time-variant systems (c) Linear systems (d) Non-linear systems (e) None of the above Ans: a 55. From which of the following transfer function can be obtained ? (a) Signal flow graph (b) Analogous table (c) Output-input ratio (d) Standard block system (e) None of the above Ans: a 56 is the reference input minus the primary feedback. (a) Manipulated variable (b) Zero sequence (c) Actuating signal (d) Primary feedback Ans: c 57. The term backlash is associated with (a) servomotors (b) induction relays (c) gear trains (d) any of the above Ans: 58. With feedback _____ increases. (a) system stability (b) sensitivity (c) gain (d) effects of disturbing signals Ans: a 59. By which of the following the system response can be tested better ? (a) Ramp input signal (b) Sinusoidal input signal (c) Unit impulse input signal (d) Exponentially decaying signal Ans: c 60. In a system zero initial condition means that (a) The system is at rest and no energy is stored in any of its components (b) The system is working with zero stored energy (c) The system is working with zero reference signal Ans: a 61. In a system low friction co-efficient facilitates (a) reduced velocity lag error (b) increased velocity lag error (c) increased speed of response (d) reduced time constant of the system Ans: a 62. Hydraulic torque transmission system is analog of (a) amplidyne set (b) resistance-capacitance parallel circuit (c) motor-generator set (d) any of the above Ans: 63. Spring constant in force-voltage analogy is analogous to (a) capacitance (b) reciprocal of capacitance (c) current (d) resistance Ans: b 64. The frequency and time domain are related through which of the following? (a) Laplace Transform and Fourier Integral (b) Laplace Transform (c) Fourier Integral (d) Either (b) or (c) Ans: a 65. An increase in gain, in most systems, leads to (a) smaller damping ratio (b) larger damping ratio (c) constant damping ratio (d) none of the above Ans: a 66. Static error co-efficients are used as a measure of the effectiveness of closed loop systems for specified ________ input signal. (a) acceleration (b) velocity (c) position (d) all of the above Ans: d 67. A conditionally stable system exhibits poor stability at (a) low frequencies (b) reduced values of open loop gain (c) increased values of open loop gain (d) none of the above Ans: b 68. The type 0 system has ______ at the origin. (a) no pole (b) net pole (c) simple pole (d) two poles (e) none of the above Ans: a 69. The type 1 system has ______ at the origin. (a) no pole (b) net pole (c) simple pole (d) two poles Ans: c 70. The type 2 system has at the origin. (a) no net pole (b) net pole (c) simple pole (d) two poles Ans: d 71. The position and velocity errors of a type-2 system are (a) constant, constant (b) constant, infinity (c) zero, constant (d) zero, zero Ans: c 72. Velocity error constant of a system is measured when the input to the system is unit _______ function. (a) parabolic (b) ramp (c) impulse (d) step Ans: b 73. In case of type-1 system steady state acceleration is (a) unity (b) infinity (c) zero (d) 10 Ans: b 74. If a step function is applied to the input of a system and the output remains below a certain level for all the time, the system is (a) not necessarily stable (b) stable (c) unstable (d) always unstable (e) any of the above Ans: a 75. Which of the following is the best method for determining the stability and transient response ? (a) Root locus (b) Bode plot (c) Nyquist plot (d) None of the above Ans: a 76. Phase margin of a system is used to specify which of the following ? (a) Frequency response (b) Absolute stability (c) Relative stability (d) Time response Ans: c 77. Addition of zeros in transfer function causes which of the following ? (a) Lead-compensation (b) Lag-compensation (c) Lead-lag compensation (d) None of the above Ans: b 78. technique is not applicable to nonlinear system ? (a) Nyquist Criterion (b) Quasi linearization (c) Functional analysis (d) Phase-plane representation Ans: a 79. In order to increase the damping of a badly underdamped system which of following compensators may be used ? (a) Phase-lead (b) Phase-lag (c) Both (a) and (b) (d) Either (a) and (b) (e) None of the above Ans: a 80. The phase lag produced by transportation relays (a) is independent of frequency (b) is inverseh'proportional to frequency (c) increases linearly with frequency (d) decreases linearly with frequency Ans: c 81. In a stable control system saturation can cause which of the following ? (a) Low-level oscillations (b) High-level oscillations (c) Conditional stability (d) Overdamping Ans: a 82. Which of the following can be measured by the use of a tacho-generator ? (a) Acceleration (b) Speed (c) Speed and acceleration (d) Displacement (e) None of the above Ans: b 83 is not a final control element. (a) Control valve (b) Potentiometer (c) Electro-pneumatic converter (d) Servomotor Ans: b 84. Which of the following is the definition of proportional band of a controller ? (a) The range of air output as measured variable varies from maximum to minimum (b) The range of measured variables from set value (c) The range of measured variables through which the air output chan¬ges from maximum to minimum (d) Any of the above (e) None of the above Ans: c 85. In pneumatic control systems the control valve used as final control element converts (a) pressure signal to electric signal (b) pressure signal to position change (c) electric signal to pressure signal (d) position change to pressure signal (e) none of the above Ans: b 86. Pressure error can be measured by which of the following ? (a) Differential bellows and straingauge (b) Selsyn (c) Strain gauge (d) Strain gauge and potentiometer Ans: a 87. Which of the following devices is used for conversion of co-ordinates ? (a) Microsyn (b) Selsyn (c) Synchro-resolver (d) Synchro-transformer Ans: c 88. The effect of error damping is to (a) provide larger settling lime (b) delay the response (c) reduce steady state error (d) any of the above (e) none of the above Ans: c 89 technique gives quick transient and stability response (a) Root locus (b) Bode (c) Nyquist (d) Nichols Ans: a 90. A phase lag lead network introduces in the output (a) lag at all frequencies (b) lag at high frequencies and lead at low frequencies (c) lag at low frequencies and lead at high frequencies (d) none of the above Ans: c 91. Which of the following is the non-linearity caused by servomotor ? (a) Static friction (b) Backlash (c) Saturation (d) None of the above Ans: c 92 can be extended to systems which are time-varying ? (a) Bode-Nyquist stability methods (b) Transfer functions (c) Root locus design (d) State model representatives Ans: d 93. When the initial conditions of a system are specified to be zero it implies that the system is (a) at rest without any energy stored in it (b) working normally with reference input (c) working normally with zero reference input (d) at rest but stores energy Ans: d 94. Which of the following is an electromechanical device ? (a) Induction relay (b) Thermocouple (c) LVDT (d) Any of the above (e) None of the above Ans: c 95. A differentiator is usually not a part of a control system because it (a) reduces damping (b) reduces the gain margin (c) increases input noise (d) increases error Ans: c 96. If the gain of the critical damped system is increased it will behave as (a) oscillatory (b) critically damped (c) overdamped (d) underdamped (e) none of the above Ans: d 97. In a control system integral error compensation _______ steady state error (a) increases (b) minimizes (c) does not have any effect on (d) any of the above Ans: b 98. With feed back _____ reduces. (a) system stability (6) system gain (c) system stability and gain (d) none of the above Ans: b 99. An amplidyne can give which of the following characteristics ? (a) Constant current (b) Constant voltage (c) Constant current as well as constant voltage (d) Constant current, constant voltage and constant power (e) None of the above Ans: d 100. Which of the following can be measured byLVDT? (a) Displacement (b) Velocity (c) Acceleration (d) Any of the above Ans: d 101 directly converts temperature into voltage. (a) Thermocouple (b) Potentiometer (c) Gear train (d) LVDT (e) None of the above Ans: a 102. The transfer function technique is considered as inadequate under which of the following conditions ? (a) Systems having complexities and non-linearities (b) Systems having stability problems (c) Systems having multiple input dis¬turbances (d) All of the above Ans: d 103. Which of the following is the output of a thermocouple ? (a) Alternating current (b) Direct current (c) A.C. voltage (d) D.C. voltage (e) None of the above Ans: d 104. A.C. servomotor is basically a (a) universal motor (b) single phase induction motor (c) two phase induction motor (d) three phase induction motor Ans: c 105. The first order control system, which is well designed, has a (a) small bandwidth (b) negative time constant (c) large negative transfer function pole (d) none of the above Ans: c 106. Which of the following is exhibited by Root locus diagrams ? (a) The poles of the transfer function for a set of parameter values (b) The bandwidth of the system (c) The response of a system to a step input (d) The frequency response of a system (e) None of the above Ans: a GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS 1. Which of the following is the major consideration to evolve a good design ? (a) Cost (b) Durability (c) Compliance with performance criteria as laid down in specifications (d) All of the above Ans: d 2 impose limitation on design. (a) Saturation (b) Temperature rise (c) Efficiency (d) Power factor (e) All above Ans: e 3. The efficiency of a machine should be as ______ as possible to reduce the operating cost. (a) high (b) low (c) either of the above (d) none of the above Ans: a 4. If an insulating material is operated beyond the maximum allowable temperature, its life is (a) drastically increased (b) drastically reduced (c) unaffected (d) none of the above Ans: b 5. The design of mechanical parts is particularly important in case of _____ speed machines. (a) low (b) medium (c) high (d) any of the above Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS 6. In induction motors, the length of air gap in kept as small as mechanically possible is order to have (a) low power factor (b) high power factor (c) high over load capacity (d) any of the above Ans: b 7. In ______ machines, the size of the shaft is decided by the critical speed which depends on the deflection of the shaft. (a) small (b) medium (c) large (d) any of the above. Ans: c 8. The length cf air gap to be provided in ______ is primarily determined by power factor consideration. (a) d.c. series motor . (b) d.c. shunt motor (c) induction motor (d) synchronous motor Ans: c 9. Electrical machines having a power output upto about 750 W may be called_______machines. (a) small size (b) medium size (c) large size (d) any of the above Ans: a 10. Electrical machines having power outputs ranging from a few kW upto approximately 250 kW may be classified as (a) small size machines (b) medium size machines (c) large size machines (d) any ofthe above Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS 11. Commercial available medium size machines have a speed range of ______ . (a) 200 to 400 r.p.m. (b) 600 to 1000 r.p.m. (c) 1000 to 1500 r.p.m. (d) 2000 to 2500 r.p.m. Ans: d 12. The action of electromagnetic machines can be related to which ofthe following basic principles ? (a) Induction (b) Interaction (c) Alignment (d) All of the above Ans: d 13. The change in flux linkages can be caused in which ofthe following ways ? (a) The flux is constant with respect to time and is stationary and the coil moves through it (b) The coil is stationary with respect to flux and the flux varies in magnitude with respect to time (c) Both the changes mentioned above occure together, i.e., the coil moves through a time varying field (d) All ofthe above Ans: d 14 is universally used for windings of electrical machines because it is easily workable without any possibility of fracture. (a) Silver (b) Steel (c) Aluminium (d) Copper Ans: d 15. Aluminium when adopted as a conductor material in ______ transformers, decreases the overall cost of the transformer (a) small size (b) medium size (c) large size Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS (d) any of the above size Ans: a 16. Which ofthe following materials is used in the manufacture of resistance grids to be used in the starters of large motors ? (a) Copper (b) Aluminium (c) Steel (d) Cast-iron Ans: d 17. Materials exhibiting zero value of resistivity are known as ______ . (a) conductors (b) semiconductors (c) insulators (d) superconductors Ans: d 18. ________ has a lowrelative permeability and is used principally in field frames when cost is of primary importance and extra weight is not objectionable. (a) Cast steel (b) Aluminium (c) Soft steel (d) Cast iron Ans: d 19 ______is extensively used for those portions of magnetic circuit which carry steady flux and need superior mechanical properties ? (a) Grey cast-iron (b) Cast steel (c) High carbon steel (d) Stainless steel Ans: b 20. Hot rolled sheets have ______ value of permeability (a) zero (b) low (c) high (d) none ofthe above Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS Ans: b 21. The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ? (a) Conduction (b) Convection (c) Radiation (d) All ofthe above Ans: d 22. The heat dissipated by from a surface depends upon its temperature and its characteristics like colour, roughness etc. (a) conduction (b) convection (c) radiation (d) any ofthe above Ans: c 23. The mcrease in heat dissipation by air blasts is due to increase in (a) conduction (b) convection (e) radiation (d) any ofthe above Ans: b 24. On which of the following variables heat convected depends ? (a) Power density (b) Temperature difference between heated surface and coolant (c) Thermal resistivity, density, specific heat (d) Gravitational constant (e) All ofthe above Ans: e 25. Which ofthe following methods is used for air cooling of turbo-alternators ? (a) One sided axial ventilation (b) Two sided axial ventilation (c) Multiple inlet system (d) All ofthe above Ans: d Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS 26. Multiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto (a) 10 MW (b) 30 MW (c) 60 MW (d) 150 MW Ans: c 27. Which ofthe following is an advantage of hydrogen cooling ? (a) Increase in efficiency (b) Increase in ratings (c) Increase in life (d) Smaller size of coolers (e) All ofthe above Ans: e 28. The density of hydrogen is _____ times the density of air. (a) 0.07 (b) 1.5 (c) 2.5 (d) 3.5 Ans: a 29. Hydrogen has a heat transfer co-efficient _____ times that of air (a) 1.5 (b) 2.5 (c) 3.5 (d) 4.5 Ans: a 30. The thermal conductivity of hydrogen is ______ times that of air (a) 2 (b) 3 (c) 5 (d) 7 Ans: d 31. With conventional hydrogen cooling it is possible to increase the rating of a single unit Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS to (a) 50 MW (b) 100 MW (c) 200 MW (d) none ofthe above Ans: c 32. The noise produced by a ______ cooled machine is less as the rotor moves in a medium of smaller density. (a) air (b) hydrogen (c) either (a) or (b) (d) none of the above Ans: b 33 cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall (a) Direct (b) Indirect (c) Conventional (d) Any ofthe above Ans: a 34. Machines cooled by direct cooling method may be called (a) "supercharged" (b) "inner cooled" (c) "conductor cooled" (d) any of the above Ans: d 35. In direct cooled system using hydrogen both stator and rotor conductors are made (a) solid (b) hollow (c) perforated (d) any ofthe above Ans: b 36. With direct water cooling it is possible to have ratings of about (a) 200 MW Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS (b) 300 MW (c) 400 MW (d) 600 MW Ans: d 37. The resistivity of water should not be less than (a) 10 Q m (b) 100 Q m (c) 1000 Q m (d) 2000 Q m Ans: d 38. Direct water cooling of rotor winding presents (a) no mechanical difficulties (b) lesser mechanical difficulties (c) greater mechanical difficulties (d) none of the above Ans: c 39. The time taken by the machine to attain 0.632 of its final steady temperature rise is called (a) heating time constant (b) cooling time constant (c) either (a) or (b) (d) none of the above Ans: a 40. In self cooled motors the cooling time constant is about ______ than the heating time constant because cooling conditions are worse at standstill. (a) 2 to 3 times greater (b) 3 to 4 times greater (c) 4 to 5 times greater (d) none of the above Ans: a 41. By which of the following methods motor rating for variable load drives can be determined ? (a) Method of average losses (b) Equivalent current method Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS (c) Equivalent torque method (d) Equivalent power method (e) All of the above. Ans: e 42. Which of the following methods does not take into account the maximum temperature rise under variable load conditions ? (a) Equivalent power method (b) Equivalent current method (c) Method of average losses (d) Equivalent torque method Ans: c 43. Which of the following methods is most accurate ? (a) Equivalent current method (b) Equivalent power method (c) Equivalent torque method (d) Method of average losses Ans: a 44. By which of the following methods the temperature rise of windings and other parts may be determined ? (a) Thermometer method (6) Resistance method (c) Embedded temperature detector method (d) Any of the above Ans: d 45. The slot leakage can be calculated by making which of the following assumptions ? (a) The current in the slot conductors is uniformly distributed over their cross-section (b) The leakage path is straight across the slot and around the iron at the bottom (c) The permanence of air paths is only considered. The reluctance of iron paths is assumed as zero (d) All of the above Ans: d 46. The value of exciting or magnetizing current depends upon which of the following factors ? (a) Total m.m.f. required Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS (b) The number of turns in the exciting winding (c) The way in which the winding is distributed (d) All of the above Ans: d 47. Tractive magnets are operated from (a) a.c. supply (b) d.c. supply (c) either a.c. or d.c. supply (d) none of the above Ans: c 48 electromagnets generally function as holding magnets. (a) Tractive (b) Portative (c) Either of the above (d) None of the above Ans: b 49. Which of the following is the commonly used type of electromagnets ? (a) Flat-faced armature type (b) Horse shoe type (c) Flat-faced plunger type (d) All of the above Ans: d 50 are used for construction of core of electromagnets. (a) Soft magnetic materials (b) Hard magnetic materials (c) Either (a) or (b) (d) None of the above Ans: a 51. The design of electromagnets is based upon which of the following fundamental equations ? (a) Force equation (b) Magnetic circuit equation (c) Heating equation (d) Voltage equation Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS (e) All of the above Ans: e 52. When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of (a) short pitch (b) full pitch (c) either of the above (d) none of the above Ans: b 53 are always double layer type. (a) Closed windings (b) Open windings (c) Either of the above (d) None of the above Ans: a 54. The distance between the starts of two consecutive coils measured in terms of coil sides is called (a) front pitch (b) winding pitch (c) commutator pitch (d) back pitch Ans: b 55. The winding where dummy coils are used is sometimes called (a) duplex winding (b) triplex winding (c) forced winding (d) none of the above Ans: c 56. Dummy coil should not be used in (a) small machines (b) large machines (c) either (a) or (b) (d) none of the above Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS 57. Power transformers have rating (a) equal to 50 kVA (6) equal to 100 kVA (c) above 200 kVA (d) none of the above Ans: c 58. Power transformers should be designed to have maximum efficiency (a) at one-fourth load (b) at one-half load (c) at or near full load (d) any of the above Ans: c 59. In transformers using hot rolled steel, the cross-section of the yoke is made about _____ greater than that of the core (a) 5 percent (b) 10 percent (c) 15 percent (d) 30 percent (e) none of the above Ans: c 60. Yokes with rectangular cross-section are used for (a) small capacity transformers (b) medium capacity transformers (c) large capacity transformers (d) any of the above Ans: a 61. The cold rolled grain oriented steel has ______ permeability in the direction of the grain orientation. (a) minimum (b) maximum (c) nil (d) none of the above Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS 62. Cylindrical windings using circular conductors, employed in transformers, are (a) single layered (b) double layered (c) multi-layered (d) none of the above Ans: c 63. Helical windings are used in (a) distribution transformers (b) power transformers (c) shell type transformers (d) none of the above Ans: b 64. Multi-layer helical windings are commonly used in the transformers as high voltage windings (a) upto 20 kV (b) upto 50 kV (c) upto 80 kV (d) for 110 kV and above Ans: d 65. Disc windings are primarily used in (a) short capacity transformers (b) medium capacity transformers (c) high capacity transformers (d) any of the above Ans: c 66. The heat dissipating capability of transformers of ratings higher than 30 kVA in increased by providing which of the following ? (a) Corrugations (b) Fins (c) Tubes (d) Radiator tanks (e) All of the above Ans: e 67. Transformers with a capacity of upto _____ have a cooling radiator system with natural Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS cooling (a) 2 MVA (b) 5 MVA (c) 7.5 MVA (d) 10 MVA Ans: d 68. The forced oil and air circulation method is usual one for transformers of capacities (a) upto 5 MVA (b) upto 10 MVA (c) upto 20 MVA (d) 30 MVA upwards Ans: d 69. The flash point of transformer oil should be higher than (a) 40°C (b) 60°C (c) 80°C (d) 104°C Ans: d 70. The voltage control in electric supply networks in required on account of which of the following reasons ? (a) Adjustment of voltage at consumers premises within statutory limits (b) Control of active and reactive power (c) Adjustment of short period daily and seasonal voltage variations in accordance with variations of load (d) All of the above Ans: d 71. D.C. windings are (a) sometimes 2-layer type (b) never 2-layer type (c) always 2-layer type (d) none of the above Ans: c 72. The usual values of maximum flux densities for distribution transformers using hot rolled silicon steel are Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS (a) 0.5 to 0.8 Wb/m2 (b) 0.8 to 1.0 Wb/m2 (c) 1.1 to 1.35 Wb/m2 (d) 1.4 to 1.8 Wb/m2 Ans: c 73. For 275 kV transformers, using cold rolled grain oriented steel, which of the following values of flux density may be used? (a) 1.0 Wb/m2 (b) 1.1 Wb/m2 (c) 1.3 Wb/m2 (d) 1.6 Wb/m2 (e) None of the above Ans: d 74. For large power transformers, self oil cooled type or air blast type which of the following values of current density may be used ? (a) 1.0 to 1.2 A/mm2 (b) 1.5 to 2.0 A/mm2 (c) 2.2 to 3.2 A/mm2 (d) 3.2 to 4.2 A/mm2 Ans: c 75. A current density of _____ is ilsed for large power transformers with forced circulation of oil or with water cooling coils (a) 1.5 to 2.5 A/mm2 (b) 3.5 to 4.5 A/mm2 (c) 4.0 to 5.0 A/mm2 (d) 5.4 to 6.2 A/mm2 Ans: d 76. The high voltage winding is usually which of the following type ? (a) Cylindrical winding with circular conductors (b) Cross-over winding with either circular or small rectangular conductors (c) Continuous disc type winding with rectangular conductors (d) All of the above types Ans: d 77. Which of the following is the basic consideration in the design of insulation ? Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS (a) Electrical considerations (b) Mechanical considerations (c) Thermal considerations (d) All of the above Ans: d 78. A practical formula for determining the thickness of insulation between low voltage and high voltage windings is (a) 1 + 0.2 kVmm (6) 2 + 0.5 kVmm (c) 4 + 0.7 kV mm (d) 5 + 0.9 kV mm Ans: d 79. The insulation between windings and grounded core and the insulation between the windings of the same phase is called (a) minor insulation (b) major insulation (c) either of the above (d) none of the above Ans: b 80. The cylindrical windings using circular conductors are used for current rating of (a) upto 20 A (b) upto 40 A (c) upto 60 A (d) upto 80 A Ans: d 81. The surge phenomenon is particularly important in case of (a) low voltage transformers (b) medium voltage transformers (c) high voltage transformers (d) any of the above Ans: c 82. Which of the following in an application of D.C. motors? (a) Traction (b) Drives for process industry Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS (c) Battery driven vehicles (d) Automatic control (e) All of the above Ans: e 83. D.C. servomotors are used in (a) purely D.C. control systems (6) purely AC. control systems (c) both D.C. and AC. control systems (d) none of the above Ans: a 84. The stator of a D.C. machine comprises of (a) main poles (6) interpoles (c) frame (d) all of the above Ans: d 85. The laminations of the armature of a D.C. machine are usually _____ thick. (a) 0.1 to 0.2 mm (b) 0.2 to 0.3 mm (c) 0.3 to 0.4 mm (d) 0.4 to 0.5 mm Ans: d 86. is usually used for brush rockers (a) Mild steel (b) Copper (c) Aluminium (d) Cast-iron Ans: d 87. ______ brushes are fragile and cause excessive wear of commutator, (a) Natural graphite (b) Hard carbon (c) Electro graphitic (d) Metal graphite Ans: a Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS 88. Which of the following brushes can be used for high values of current density ? (a) Metal graphite brushes (b) Hard carbon brushes (c) Electro-graphitic brushes (d) Natural graphite brushes Ans: a 89 ________ is the common method of applying brushes to the commntator. (a) Radial (b) Trailing (c) Reaction (d) All of the above Ans: d 90. Which of the following problem arises in D.C. motors which are fed from thyristor bridge circuits ? (a) Increased I R losses (b) Increased core losses (c) Poor commutation (d) Change in motor parameters (e) All of the above Ans: e 91. The weight of copper of both armature and field windings decreases with _____ in number of poles. (a) increase (b) decrease (c) either of the above (d) none of the above Ans: a 92. In a D.C. machine the number of brush arms is _____ the number of poles. (a) less than (b) equal to (c) greater than (d) none of the above Ans: b Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS 93. In a D.C. machine the current per brush arm should not be more than (a) 100 A (6) 200 A (e) 300 A (d) 400 A Ans: d 94. In a D.C. machine, the value of peripheral speed should not, normally, exceed (a) 10 m/s (b) 20 m/s (c) 30 m/s (d) 40 m/s Ans: c 95. In D.C. machines the width of the duct is usually (a) 4 mm (b) 6 mm (c) 8 mm (d) 10 mm Ans: d 96. D.C. machines designed with a large value of air gap length have (a) worst, ventilation (b) poor ventilation (c) better ventilation (d) none of the above Ans: c 97. In D.C. machines, ir order to prevent excessive distortion of field form by the armature reaction, the field mmf must be made (a) equal to that of armature mmf (b) less in comparison with the arma¬ture mmf (c) large in comparison with the arma-ture mmf (d) none of the above Ans: c 98. In D.C. machines, the ____ in field mmf results in increase in size and cost of machines. (a) increase (b) decrease Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR DESIGN OF ELECTRICAL MACHINES OBJECTIVE TYPE QUESTIONS (c) either of the above (d) none of the above Ans: a 99. The operation of a D.C. machine with large air gap lengths is comparatively (a) quiet (b) noisy (c) either of the above (d) none of the above Ans: a 100. Which of the following methods may be adopted to reduce the effects of armature reaction ? (a) Increase in length of air gap at pole tips (b) Increasing reluctance of pole tips (c) Compensating windings (d) Interpoles (e) All of the above Ans: e 101. In D.C. machines the usual limit of slot pitch is (a) between 5 to 10 mm (b) between 10 to 15 mm (c) between 15 to 20 mm (d) between 25 to 35 mm Ans: d 102. In D.C. machines the number of slots per pole usually lies (a) between 2 to 4 (b) between 6 to 8 (c) between 9 to 16 (d) between 20 to 30 Ans: c Prepared by Mr. V. Arivumani, Asst Professor, Dept of EEE, GCE, Bargur GOVERNMENT COLLEGE OF ENGINEERING, BARGUR ELECTROMAGNETIC THEORY MULTIPLE CHOICE QUESTIONS ELECTROSTATICS 1. The force between two charges is 120 N. If the distance between the charges is doubled, the force will be (a) 60 N (b) 30 N (c) 40 N (d) 15 N Ans: b 2. The electric field intensity at a point situated 4 metres from a point charge is 200 N/C. If the distance is reduced to 2 metres, the field intensity will be (a) 400 N/C (b) 600 N/C (c) 800 N/C (d) 1200 N/C Ans: c 3. The lines of force due to charged particles are (a) always straight (b) always curved (c) sometimes curved (d) none of the above Ans: b 4. The electric field at a point situated at a distance d from straight charged conductor is (a) proportional to d (b) inversely proportional to d (c) inversely proportional to d (d) none of the above Ans: b 5. The direction of electric field due +0 positive charge is . (a) away from the charge (b) towards the charge (c) both (a) and (6) (d) none of the above Ans: a 6. A field line and an equipotential surface are (a) always parallel (b) always at 90° (c) inclined at any angle 0 (d) none of the above Ans: b 7. The ability of charged bodies to exert force on 6ne another is attributed to the existence of (a) electrons (b) protons (c) neutrons (d) electric field Ans: d 8. If the sheet of a bakelite is inserted between the plates of an air capacitor, the capacitance will (a) decrease (b) increase (c) remains unchanged (d) become zero Ans: b 9. A capacitor stores 0.24 coulombs at 10 volts. Its capacitance is (a) 0.024 F (b) 0.12 F (c) 0.6 F (d) 0.8 F Ans: a 10. For making a capacitor, it is better to select a dielectric having (a) low permittivity (b) high permittivity (c) permittivity same as that of air (d) permittivity slightly more than that of air Ans: b 11. The units of capacitance are (a) volts/coulomb (b) coulombs/volt (c) ohms (d) henry/Wb Ans: b 12. If three 15 uF capacitors are connected in series, the net capacitance is (a) 5 uF (6) 30 uF (c) 45 uF (d) 50 uF Ans: a 13. If three 10 uF capacitors are connected in parallel, the net cararitance is (a) 20 uF (b) 30 uE (c) 40 uF (d) 50 uF Ans: b 14. A dielectric material must be (a) resistor (b) insulator (c) good conductor (d) semi conductor Ans: b 15. An electrolytic capacitor can be used for (a) D.C. only (b) AC. only (c) both D.C. as well as A.C. Ans: a 16. The capacitance of a capacitor is not affected by (a) distance between plates (6) area of plates (c) thickness of plates (d) all of the above Ans: c 17. Which of the following is not a vector ? (a) Linear momentum (b) Angular momentum (c) Electric field (d) Electric potential Ans: b 18. Two plates of a parallel plate capacitor after being charged from a constant voltage source are separated apart by means of insulated handles, then the (a) Voltage across the plates increases (b) voltage across the plates decreases (c) charge on the capacitor decreases (d) charge on the capacitor increases Ans: b 19. If A.C. voltage is applied to capacitive circuit, the alternating current can flow in the circuit because (a) varying voltage produces the charg¬ing and dicharging currents (b) of high peak value (c) charging current can flow (d) discharge current can flow Ans: a 20. Voltage applied across a ceramic dielectric produces an electrolytic field 100 times greater than air. What will be the value of dielectric constant ? (a) 50 (6) 100 (c) 150 (d) 200 Ans: b 21. Which of the following statements is correct ? (a) Air capacitors have a blackband to indicate the outside foil (6) Electrolytic capacitor must be con¬nected in the correct polarity (c) Ceramic capacitors must be con¬nected in the correct polarity (d) Mica capacitors are available in capacitance value of 1 to 10 pF Ans: b 22. The dissipation factor of a good dielectric is of the order of (a) 0.0002 (b) 0.002 (c) 0.02 (d) 0.2 Ans: a 23. "The total electric flux through any closed surface surrounding charges is equal to the amount oflcharge enclosed". The above statement is associated with (a) Coulomb's square law (b) Gauss's law (c) Maxwell's first law (d) Maxwell's second law Ans: b 24. Three capacitors each of the capacity C are given. The resultant capacity 2/3 C can be obtained by using them (a) all in series (b) all in parallel (c) two in parallel and third in series with this combination (d) two in series and third in parallel across this combination Ans: c 25. For which of the following parameter variation, the capacitance of the capacitor remains unaffected ? (a) Distance between plates (b) Area of the plates (c) Nature of dielectric (d) Thickness of the plates Ans: d 26. Which of the following statement is true ? (a) The current in the discharging capacitor grows linearly (b) The current in the dicharging capacitor grows exponentially (c) The current in the discharging capacitor decays exponentially (d) The current in the discharging capacitor decreases constantly Ans: b 27. Which of the following expression is correct for electric field strength ? (a) E = D/E (b) E = D2/t (c) E = jtD (d) E= nD2 Ans: a 28. In a capacitor the electric charge is stored in (a) metal plates (b) dielectric (c) both (a) and (6) (d) none of the above Ans: b 29. Which of the following materials has the highest value of dielectric constant? (a) Glass (b) Vacuum (c) Ceramics (d) Oil Ans: c 30. Which of the following capacitors will have the least variation ? (a) Paper capacitor (b) Ceramic capacitor (c) Silver plated mica capacitor (d) None of the above Ans: c 31. Which of the following statements is incorrect ? (a) The leakage resistance of ceramic capacitors is generally high (b) The stored energy in a capacitor decreases with reduction in value of capacitance (c) The stored energy in a capacitor increases with applied voltage (d) A wire cable has distributed capacitance between the conductors Ans: b 32. Which of the following capacitors has relatively shorter shelf life ? (a) Mica capacitor (b) Electrolytic capacitor (c) Ceramic capacitor (d) Paper capacitor Ans: b 33. The sparking between two electrical contacts can be reduced by inserting a (a) capacitor in parallel with contacts (6) capacitor in series with each contact (c) resistance in line (d) none of the above Ans: a 34. In the case of a lossy capacitor, its series equivalent resistance value will be (a) small (b) very small (c) large (d) zero Ans: c 35. The power dissipated in a pure capacitor is (a) zero (6) proportional to applied voltage (c) proportional to value of capacitance (d) both (b) and (c) above Ans: a 36. In a capacitive circuit (a) a steady value of applied voltage causes discharge (b) an increase in applied voltage makes a capacitor charge (c) decrease in applied voltage makes a capacitor charge (d) none of the above Ans: b 37. When a dielectric slab is introduced in a parallel plate capacitor, the potential difference between plates will (a) remain uncharged (b) decrease (c) increase (d) become zero Ans: b 38. Capacitance increases with (a) increase in plate area and decrease in distance between the plates (b) increase in plate area and distance between the plates (c) decrease in plate area and value of applied voltage (d) reduction in plate area and distance between the plates Ans: a 39. A capacitor consists of (a) two insulators separated by a con¬ductor (b) two conductors separated by an in¬sulator (c) two insulators only (d) two conductors only Ans: b 40. A gang condenser is a (a) polarised capacitor (6) variable capacitor (c) ceramic capacitor (d) none of the above Ans: 41. A paper capacitor is usually available in the form of (a) tubes (b) rolled foil (c) disc (d) meshed plates Ans: b 42. Air capacitors are generally available in the range (a) 10 to 400 pF (b) 1 to 20 pF (c) 100 to 900 pF (d) 20 to 100 pF Ans: a 43. The unit of capacitance is (a) henry (b) ohm (c) farad (d) farad/m Ans: c 44. A capacitor charged to 200 V has 2000 (iC of charge. The value of capacitance will be (a) 10 F (6) 10 uF (c) 100 nF (d) 1000 uF Ans: b 45. A capacitor in a circuit became hot and ultimately exploded due to wrong con¬nections, which type of capacitor it could be ? (a) Paper capacitor (b) Ceramic capacitor (c) Electrolytic capacitor (d) Any-of the above Ans: c 46. Energy stored in the electric field of a capacitor C when charged from a D.C source of voltage V is equal to joules (a) CV2 (b) C2V (c) CV2 (d) CV Ans: a 47. The absolute permittivity of free space is given by (a) 8.854 x 1(T9 F/m) (6) 8.854 x 1(T10 F/m) (c) 8.854 x KT11 F/m (d) 8.854 x 10"12 F/m Ans: b 48. The relative permittivity of free space is given by (a) 1 (b) 10 (c) 100 (d) 1000 Ans: a 49. Electric field intensity is a quantity (a) scalar (b) vector (c) both (a) and (6) (d) none of the above Ans: b 50. When 4 volts e.m.f. is applied across a 1 farad capacitor, it will store energy of (a) 2 joules (b) 4 joules (c) 6 joules (d) 8 joules Ans: d 51. The capacitor preferred for high frequency circuits is (a) air capacitor (b) mica capacitor (c) electrolytic capacitor (d) none of the above Ans: b 52. The capacity of capacitor bank used in power factor correction is expressed in terms of (a) kW (b) kVA (c) kVAR (d) volts Ans: c 53. While testing a capacitor with ohm-metre, if the capacitor shows charging, but the final resistance reading is appreciably less than normal, it can be concluded that the capacitor is (a) short-circuited (b) open circuited (c) alright (d) leaky Ans: d 54. If a 6 (iF capacitor is charged to 200 V, the charge in coulombs will be (a) 800 uC (b) 900 uC (c) 1200 uC (d) 1600 uC Ans: c 55. Which capacitor will be physically smaller for the same ratings ? (a) Ceramic capacitor (b) Paper capacitor (c) Both will be of equal size (d) None of the above Ans: a 56. What is the value of capacitance that must be connected in parallel with 50 pF condenser to make an equivalent capacitance of 150 pF ? (a) 50 pF (b) 100 pF (c) 150 pF (d) 200 pF Ans: b 57. A mica capacitor and a ceramic capacitor both have the same physical dimensions. Which will have more value of capacitance ? (a) Ceramic capacitor (b) Mica capacitor (c) Both will have identical value of capacitance (d) It depends on applied voltage Ans: a 58. Which of the following material has least value of dielectric constant ? (a) Ceramics (b) Oil (c) Glass (d) Paper Ans: b 59. Which of the following capacitors will have the least value of breakdown voltage ? (a) Mica (b) Paper (c) Ceramic (d) Electrolytic Ans: d 3.73. The breakdown voltage for paper capacitors is usually (a) 20 to 60 volts (b) 200 to 1600 volts (c) 2000 to 3000 volts (d) more than 10000 volts Ans: 60. Dielectric constant for mica is nearly (a) 200 (b) 100 (c) 3 to 8 (d) 1 to 2 Ans: c 61. The value of dielectric constant for vacuum is taken as (a) zero (b) 1 (c) 4 (d) 10 Ans: b 62. Which of the following capacitors is marked for polarity ? (a) Air (b) Paper (c) Mica (d) Electrolytic Ans: d 63. Which of the following capacitors can be used for temperature compensation ? (a) Air capacitor (b) Ceramic capacitor (c) Paper capacitor (d) None of the above Ans: b 64. Which of the following statements is incorrect ? (a) The thinner the dielectric, the more the capacitance and the lower the voltage breakdown rating for a capacitor . (b) A six dot mica capacitor colour coded white, green, black, red and yellow has the capacitance value of 500 pF (c) Capacitors in series provide less capacitance but a higher voltage breakdown rating for the combina¬tion (d) A capacitor can store charge be¬cause it has a dielectric between two conductors Ans: b 65. Paper capacitors usually have a tolerance of (a) ± 5% (b) ± 10% (c) ± 15% (d) ± 20% Ans: b 66. For closer tolerances which of the following capacitors is usually preferred ? (a) Paper capacitor (b) Mica capacitor (c) Ceramic disc capacitor (d) None of the above Ans: b 67. The electrostatic force between two charges of one coulomb each and placed at a distance of 0.5 m will be (a) 36 x 10fa (b) 36 x 107 N (c) 36 x 108 N (d) 36 x 109 N Ans: d 68. The units of volume charge density are (a) Coulomb/metre (b) Coulomb/metre (c) Coulomb/metre (d) Coulomb/metre Ans: c 69. "The surface integral of the normal component of the electric displacement D over any closed surface equals the charge enclosed by the surface". The above statement is associated with (a) Gauss's law (b) Kirchhoff s law (c) Faraday's law (d) Lenz's law Ans: a 70. Dielectric strength of mica is (a) 10 to 20 kV/mm (6) 30 to 50 kV/mm (c) 50 to 200 kV/mm (d) 300 to 500 kV/mm Ans: c 71. The dielectric constant (relative permittivity) of glass is given by (a) 0.1 to 0.4 (b) 0.5 to 1.0 (c) 2.0 to 4.0 (d) 5 to 100 Ans: d 72 capacitors are mainly used for radio frequency tuning. (a) Paper (b) Air (c) Mica (d) Electrolytic Ans: b 73. capacitors can be used only for D.C. (a) Air (b) Paper (e) Mica (d) Electrolytic Ans: d 74. capacitors are used in transistor circuits. (a) Ceramic (b) Paper (c) Air (d) Electrolytic Ans: a 75. capacitors are used for audio frequency and radio frequency coupling and tuning. (a) Air (b) Mica (c) Plastic film (d) Ceramic Ans: b 76. The inverse of capacitance is called (a) reluctance (b) conductance (c) susceptance (d) elastance Ans: d 77. When the dielectric is homogeneous,the potential gradient is (a) uniform (b) non-uniform (c) zero (d) any of the above Ans: a 78. The potential gradient across the material of low permittivity is than across the material of high permittivity. (a) smaller (b) greater (c) both (a) and (b) (d) none of the above Ans: b 79. ________field is associated with the capacitor. (a) Electric (b) Magnetic (c) Both (a) and (b) (d) None of the above Ans: a 80. A capacitor having capacitance of 5 uF is charged to a potential difference of 10,000 V. The energy stored in the capacitor is (a) 50 joules (b) 150 joules (c) 200 joules (d) 250 joules Ans: d 81. A single core cable used on 33000 V has conductor diameter 10 mm and the in¬ternal diameter of sheath 25 mm. The maximum electrostatic stress in the cable is (a) 62 x 105 V/m (b) 72 x 105 V/m (c) 82 x 105 V/m (d) 92 x 105 V/m Ans: b 82. Two infinite parallel plates 10 mm apart have maintained between them a potential difference of 100 V. The acceleration of an electron placed between them is (a) 0.56 x 1015 m/s2 (b) 1.5 x 1015 m/s2 (c) 1.6 x 1015 m/s2 (d) 1.76 x 1015 m/s2 Ans: d 83. The total deficiency or excess of electrons in a body is known as (a) current (b) voltage (c) potential gradient (d) charge Ans: d 84. The relative permittivity has the following units (a) F/m (b) m/F (c) Wb/m (d) no units Ans: c 85. The phenomenon of an uncharged body getting charged merely by the nearness of a charged body is known as (a) pholoelectric effect (b) chemical effect (c) magnetic effect (d) induction Ans: d 86. A unit tube of flux is known as tube (a) Newton (b) Faraday (c) Michale (d) None of the above Ans: b 87. The number of Faraday tubes of flux passing through a surface in an electric field is called (a) electric flux (6) electric flux density (c) magnetic flux density (d) electric charge density Ans: a 88. The unit of electric instensity is (a) N/C2 (b) Wb/m2 (c) N/C (d) N2/C Ans: 89. The value of E within the field due to a point charge can be found with the help of (a) Faraday's laws (b) Kirchhoff s laws (c) Coulomb's laws (d) none of the above Ans: c 90. at a point may be defined as equal to the lines of force passing normally through a unit cross section at that point. (a) Electric intensity (6) Magnetic flux density (c) Electric flux (d) None of the above Ans: a 91. Electric intensity at any point in an electric field is equal to the at that point. (a) electric flux (b) magnetic flux density (c) potential gradient (d) none of the above Ans: c 92. Electric displacement is a______quantity. (a) scalar (b) vector (c) both of the above (d) none of the above Ans: b 93. at a point is equal to the negative potential gradient at that point. (a) Electric intensity (6) Electric flux (c) Magnetic flux (d) Magnetic flux density Ans: a 94. The unit of dielectric strength is given by (a) V/m (b) V2/m (c) m/V (d) m/V2 Ans: a 95. Dielectric strength ______ with increasing thickness (a) increases (b) decreases (c) remains unaltered (d) none of the above Ans: b 96. The property of a capacitor to store electricity is called its (a) capacitance (b) charge (c) energy (d) none of the above Ans: a 97. is that property of a capacitor which delays any change of voltage across it. (a) Inductance (b) Capacitance (c) Potential gradient (d) None of the above Ans: b 98. A capacitance of 100 fiF is connected in series with a resistance of 8000 £2. The time constant of the circuit is (a) 0.2 s (b) 0.4 s (c) 0.6 s (d) 0.8 s Ans: d 99. In a cable capacitor, voltage gradient ismaximum at the surface of the (a) earth (b) conduction (c) sheath (d) insulator Ans: b 100. The time constant of an R-C circuit is defined as the time during which capacitor charging voltage actually rises to ______ percent of its______value. (a) 37, initial (b) 63.2, initial (c) 63.2, final (d) 37, final Ans: c 101. The time constant and R-C circuit may also be defined as the time during which the charging current falls to ______ percent of its initial maximum value, (a) 37 (b) 42 (c) 63 (d) 73 Ans: a 102. The capacitance of a capacitor is influenced by (a) plate area (b) plate separation (c) nature of dielectric (d) none of the above (e) all of the above Ans: 103. A capacitor consists of two (a) ceramic plates and one mica disc (b) insulators separated by a dielectric (c) silver-coated insulators (d) conductors separated by an insulator Ans: d 104. Permittivity is expressed in (a) Farad/sq-m (b) Farad/metre (c) Weber/metre (d) Weber/sq-m Ans: b 105. Dielectric strength of a material depends on (a) moisture content (b) temperature (c) thickness (d) all of the above (e) none of the above Ans: d 106. What will happen to an insulating medium if voltage more than the breakdown voltage is applied on it ? (a) It will become magnetic (b) It will melt (c) It will get punctured or cracked (d) Its molecular structure will get changed Ans: c 107. Which medium has the least dielectric strength ? (a) Paraffin wax (b) Quartz (c) Glass (d) Air Ans: d 108. 1 volt/metre is same as (a) 1 metre/coulomb (6) 1 newton metre (c) 1 newton/metre (d) 1 joule/coulomb Ans: c 109. One volt is the same as (a) one joule/coulomb (b) one coulomb/joule (c) one coulomb (d) one joule Ans: a 110. The capacitance between two plates increases with (a) shorter plate area and higher ap¬plied voltage (6) shorter plate area and shorter dis¬tance between them (c) larger plate area, longer distance between plates and higher,applied voltage (d) larger plate area and shorter distance between plates Ans: d 111. The capacitance C is charged through a resistance R. The time constant of the charging circuit is given by (a) CIR (b) 1/RC (c) RC (d) RIC Ans: c 112. The bridge used for the measurement of the value of the capacitance is (a) Wien's bridge (b) Wheatstone bridge (c) Schering bridge (d) Hay's bridge Ans: c 113. If an ohmmeter reading immediately goes practically to zero and stays there, capacitor is (a) charged (b) short-circuited (c) lossy (d) satisfactory Ans: b 114. Out of the following capacitors of identical rating which one will have the smallest dimensions ? (a) Aluminium foil capacitor (b) Mica capacitor (c) Ceramic capacitor (d) Paper capacitor Ans: c 115. An uncharged conductor is placed near a charged conductor, then (a) the uncharged conductor gets charged by conduction (6) the uncharged conductor gets charged by induction and then attracted towards the charging body (c) the uncharged conductor is attracted first and then charged by induction (d) it remains as such Ans: b 116. The presence of an uncharged conductor near a charged one increases the (a) charge of the charged conductor (6) capacity of the charged conductor (c) potential of the charged conductor (d) all of the above Ans: b 117. Paper condenser is (a) always polarised (6) usually of fixed value (c) electrolytic condenser (d) a variable condenser Ans: b 118. Mica capacitors are characterised by all of thte following except (a) stable operation (b) accurate value (c) low leakage reactance (d) low losses Ans: c 119. A potential of 400 V is applied to a capacitor, the plates of which are 4 mm apart. The strength of electric field is (a) 100 kV/m (b) 10 kV/m (c) 5 kV/m (d) 2 kV/m Ans: a 120. For a good 0.05 uF capacitor ohmmeter reading should (a) show low resistance momentarily and back off to a very high resis¬tance (6) show high resistance momentarily and then a very low resistance (c) go quickly to 50 ohm approximately and remain there (d) not move at all Ans: a 121. The ohmmeter reading for a short circuited capacitor is (a) infinity (b) few kilo ohms (c) few megaahms (d) zero Ans: d 122. Which of the following statements is correct ? (a) Mica capacitors are available in capacitance values of 5 to 20 \iF (b) Air capapitors have a black band to indicate the outside foil (c) Electrolytic capacitors must be connected in correct polarity (d) Ceramic capacitors must be con¬nected in correct polarity Ans: c 123. Which of the following capacitors preferred for high frequency circuits ? (a) Air capacitor (b) Electrolytic capacitor (c) Mica capacitor (d) none of the above Ans: c 124. An electrolytic capacitor is generally made to provide (a) low capacitance (b) fixed capacitance (c) variable capacitance (d) large value of capacitance Ans: d 125. In order to remove static electricity from machinery (a) construct insulated cabins (b) insulate the machinery (c) ground the framework (d) humidify the surroundings Ans: c 126. If a third equal and similar charge is placed between two equal and similar charges, then this third charge will (a) move out of the field of influence of the two charges (b) remain in stable equilibrium (c) not be in equilibrium (d) be in unstable equilibrium Ans: b 127. A region around a stationary electric charge has (a) an electric field (b) a magnetic field (c) both (a) and (b) (d) none of the above Ans: a 128. The minimum value of potential gradient in a cable occurs in (a) insulation (b) conductor (c) outer sheath (d) uniformly all over Ans: a 129. Dielectric strength of medium (a) increases with rise in temperature (b) increases with moisture content (c) is same for all insulating materials (d) none of the above Ans: d 130. Acharge which when placed in vacuum from an equal and similar charge repels with a force of 9 x 10 N, is known as (a) milli-coulomb (b) micro-coulomb (c) pico-coulomb (d) coulomb Ans: b 131. Dielectric strength of a medium is usually expressed in (a) J/mm (b) C/m2 (c) kV/mm (d) N/mm Ans: c 132. A positive and a negative charge are initially 50 mm apart. When they are moved close together so that they are now only 10 mm apart, the force between them will be (a) 5 times smaller than before (b) 5 times greater than before (c) 10 times greater than before (d) 25 times larger than before Ans: d 133. Which is the most superior dielectric out of the following ? (a) Air (b) Glass (c) Bakelite (d) Paper Ans: c 134. When a dielectric is placed in an electric field the field strength (a) decreases (b) increases (c) reduces to zero (d) remain unchanged Ans: a 135. To prevent the generation of static charges on rubber or flat leather (a) surface is moistened (b) conductive dressing is done (c) oil compound dressing is done (d) talcum powder is sprayed on the surface Ans: b 136. Which of the following capacitor is preferred in case of single phase motor ? (a) Mica capacitor (b) Paper capacitor (c) Electrolytic capacitor (d) Ceramic capacitor Ans: c 137. A capacitance is a circuit component that opposes the change in circuit (a) current (b) voltage (c) impedance (d) none of the above Ans: a 138. A condenser suitable for D.C. only is (a) metallic plate variable gang condenser (b) metallic paper capacitor (c) oil impregrated paper condenser (d) poled aluminium electrolytic condenser Ans: d 139. In a capacitor, the electric charge is stored in (a) metal plates (b) dielectric (c) dielectric as well as metal plates (d) none of the above Ans: b MAGNETISM AND ELECTROMAGNETISM 1. Tesla is a unit of (a) field strength (b) inductance (c) flux density (d) flux Ans: c 2. A permeable substance is one (a) which is a good conductor (6) which is a bad conductor (c) which is a strong magnet (d) through which the magnetic lines of force can pass very easily Ans: d 3. The materials having low retentivity are suitable for making (a) weak magnets (b) temporary magnets (c) permanent magnets (d) none of the above Ans: b 4. A magnetic field exists around (a) iron (b) copper (c) aluminium (d) moving charges Ans: d 7. Ferrites are materials. (a) paramagnetic (b) diamagnetic (c) ferromagnetic (d) none of the above Ans: c 8. Air gap has_______eluctance as compared to iron or steel path (a) little (b) lower (c) higher (d) zero Ans: b 9. The direction of magnetic lines of force is (a) from south pole to north pole (b) from north pole to south pole (c) from one end of the magnet to another (d) none of the above Ans: b 10. Which of the following is a vector quantity ? (a) Relative permeability (b) Magnetic field intensity (c) Flux density (d) Magnetic potential Ans: b 11. The two conductors of a transmission line carry equal current I in opposite directions. The force on each conductor is (a) proportional to 7 (b) proportional to X (c) proportional to distance between the conductors (d) inversely proportional to I Ans: b 12. A material which is slightly repelled by a magnetic field is known as (a) ferromagnetic material (b) diamagnetic material (c) paramag>etic material (d) conducting material Ans: b 13. When an iron piece is placed in a magnetic field (a) the magnetic lines of force will bend away from their usual paths in order to go away from the piece (b) the magnetic lines of force will bend away from their usual paths in order to pass through the piece (c) the magnetic field will not be affected (d) the iron piece will break Ans: b 14. Fleming's left hand rule is used to find (a) direction of magnetic field due to current carrying conductor (b) direction of flux in a solenoid (c) direction of force on a current car¬rying conductor in a magnetic field (d) polarity of a magnetic pole Ans: c 15. The ratio of intensity of magnetisation to the magnetisation force is known as (a) flux density (b) susceptibility (c) relative permeability (d) none of the above Ans: b 16. Magnetising steel is normals difficult because (a) it corrodes easily (6) it has high permeability (c) it has high specific gravity (d) it has low permeability Ans: d 17. The left hand rule correlates to (a) current, induced e.m.f. and direc¬tion of force on a conductor (b) magnetic field, electric field and direction of force on a conductor (c) self induction, mutual induction and direction of force on a conductor (d) current, magnetic field and direc¬tion of force on a conductor Ans: d 18. The unit of relative permeability is (a) henry/metre (b) henry (c) henry/sq. m (d) it is dimensionless Ans: d 19. A conductor of length L has current I passing through it, when it is placed parallel to a magnetic field. The force experienced by the conductor will be (a) zero (b) BLI (c) B2LI (d) BLI2 Ans: a 20. The force between two long parallel conductors is inversely proportional to (a) radius of conductors (b) current in one conductor (c) product of current in two conduc¬tors (d) distance between the conductors Ans: d 21. Materials subjected to rapid reversal of magnetism should have (a) large area oiB-H loop (b) high permeability and low hysteresis loss (c) high co-ercivity and high reten-tivity (d) high co-ercivity and low density Ans: b 22. Indicate which of the following material does not retain magnetism permanently. (a) Soft iron (b) Stainless steel (e) Hardened steel (d) None of the above Ans: a 23. The main constituent of permalloy is (a) cobalt (b) chromium (c) nickel (d) tungsten Ans: c 24. The use of permanent magnets is. not made in (a) magnetoes (6) energy meters (c) transformers (d) loud-speakers Ans: c 25. Paramagnetic materials have relative permeability (a) slightly less than uuity (b) equal to unity (c) slightly more than unity (d) equal to that ferromagnetic mate rials Ans: c 26. Degaussing is the process of (a) removal of magnetic impurities (b) removing gases from the materials (c) remagnetising metallic parts (d) demagnetising metallic parts Ans: 27. Substances which have permeability less than the permeability of free space are known as (a) ferromagnetic (b) paramagnetic (c) diamagnetic (d) bipolar Ans: c 28. Two infinitely long parallel conductors in vacuum anf' separated 1 metre between centres >rhen a current of 1 ampere flows thn. ugh each conductor, produce on each otLer a force of (a) 2 x 1(T2 N/m) (b) 2 x KT3 N/m (c) 2 x 10"5 N/m (d) 2x 1(T7 N/m) Ans: d 29. In the left hand rule, forefinger always represents (a) voltage (b) current (c) magnetic field (d) direction of force on the conductor Ans: c 30. Which of the following is a ferromagnetic material ? (a) Tungsten (b) Aluminium (c) Copper (d) Nickel Ans: d 31. Ferrites are a sub-group of (a) non-magnetic materials (b) ferro-magnetic materials (c) paramagnetic materials (d) ferri-magnetic materials Ans: d 32. Gilbert is a unit of (a) electromotive force (b) magnetomotive force (c) conductance (d) permittivity Ans: b 33. The working of a meter is based on the use of a permanent magnet. In order to protect the meter functioning from stray magnetic fields (a) meter is surrounded by strong magnetic fields (b) a soft iron shielding is used (c) a plastic shielding is provided (d) a shielding of anon-magnetic material is used Ans: b 34. Reciprocal of permeability is (a) reluctivity (b) susceptibility (c) permittivity (d) conductance Ans: a 35. The relative permeability is less than unity is case of (a) ferromagnetic materials (b) ferrites (c) non-ferrous materials (d) diamagnetic materials Ans: d 36. Which of the following is the unit of magnetic flux density ? (a) weber (b) lumens (c) tesla (d) none of the above Ans: c 37. The magnetism left in the iron after exciting field has been removed is known as (a) permeance (b) residual magnetism (c) susceptance (d) reluctance Ans: b 38. Which of the following is not a unit of flux? (a) Maxwell (b) Telsa (c) Weber (d) All of the above Ans: b 39. Which of the following is expected to have the maximum permeability ? (a) Brass (b) Copper (c) Zinc (d) Ebonite Ans: d 40. One telsa is equal to (a) 1 Wb/mm2 (b) 1 Wb/m (c) 1 Wb/m2 (d) 1 mWb/m2 Ans: c 42. Out of the following statements, concerning an electric field, which statement is not true ? (a) The electric intensity is a vector quantity (b) The electric field intensity at a point is numerically equal to the force exerted upon a charge placed at that point (c) An electric field is defined as a point in space at which an electric charge would experienc* a force (d) Unit field intensity in the exertion of a force of one newton on a charge of one coulomb Ans: b 43. When a magnet is in motion relative to a coil the induced e.m.f. does not depend upon (a) resistance of the coil (b) motion of the magnet (c) number of turns of the coil (d) pole strength of the magnet Ans: a 44. One maxwell is equal to (a) 10 webers (b) 10 webers (c) 10 webers (d) 10 webers Ans: d 46. When two ends of a circular uniform wire are joined to the terminals of a battery, the field at the centre of the circle (a) will be zero (b) will be infinite (c) will depend on the amount of e.m.f. applied (d) will depend on the radius of the circle Ans: d 47. Susceptibility is positive for (a) non-magnetic substances (b) diamagnetic substances (c) ferromagnetic substances (d) none of the above Ans: c 48. Two long parallel conductors carry 100 A. If the conductors are separated by 20 mm, the force per metre of length of each conductor will be (a) 100 N (b) 10 N (c) 1 N (d) 0.1 N Ans: d 49. A 300 mm long conductor is carrying a current of 10 A and is situated at right angles to a magnetic field having a flux density of 0.8 T ; the force on the conductor will be (a) 240 N (6) 24 N (c) 2.4 N (d) 0.24 N Ans: c 50. A 200 turn coil having an axial length of 30 mm and a radius of 10 mm is pivoted in a magnetic field having a flux density of 0.8 T. If the coil carries a current of 0.5 A, the torque acting on the coil will be (a) 4.8 N-m (b) 0.48 N-m (e) 0.048 N-m (d) 0.0048 N-m [Hint. Torque = 2BIlNr N-m] Ans: c 51. The electromagnet has 50 turns and a current of 1A flows through the coil. If the length of the magnet circuit is 200 mm, what is the magnetic field strength ? (a) 2500 AT/m (b) 250 AT/m (c) 25 AT/m (d) 2.5 AT/m Ans: b 52. What is the magnitude and the direction of force per 1.1m length of a pair of conductors of a direct current linecarrying 10 amperes and spaced 100 mm apart ? (a) 22 x 10"8 N (b) 22 x 10"7 N (c) 22 x 10-6 N (d) 22 x 10"5 N Ans: d 53. A square cross-sectional magnet has a pole strength of 1 x 10 Wb and cross sectional area of 20 mm x 20 mm. What is the strength at a distance of 100 mm from the unit pole in air ? (a) 63.38 N/Wb (b) 633.8 N/Wb (c) 6338 N/Wb (d) 63380 N/Wb Ans: c 56. The unit of flux is the same as that of (a) reluctance (b) resistance (c) permeance (d) pole strength Ans: d 57. Unit for quantity of electricity is (a) ampere-hour (b) watt (c) joule (d) coulomb Ans: d 58. The Biot-savart's law is a general modification of (a) Kirchhoffs law (b) Lenz's law (c) Ampere's law (d) Faraday's laws Ans: c 61. The most effective and quickest may of making a magnet from soft iron is by (a) placing it inside a coil carrying current (b) induction (c) the use of permanent magnet (d) rubbing with another magnet Ans: a 62. The commonly used material for shielding or screening magnetism is (a) copper (b) aluminium (c) soft iron (d) brass Ans: c 63. If a copper disc is rotated rapidly below a freely suspended magnetic needle, the magnetic needle shall start rotating with a velocity (a) less than that of disc but in opposite direction (b) equal to that of disc and in the same direction (c) equal to that of disc and in the opposite direction (d) less than that of disc and in the same direction Ans: d 64. A permanent magnet (a) attracts some substances and repels others (b) attracts all paramagnetic substan¬ces and repels others (c) attracts only ferromagnetic sub¬stances (d) attracts ferromagnetic substances and repels all others Ans: a 65. The retentivity (a property) of material is useful for the construction of (a) permanent magnets (b) transformers (c) non-magnetic substances (d) electromagnets Ans: a 66. The relative permeability of materials is not constant. (a) diamagnetic (b) paramagnetic (c) ferromagnetic (d) insulating Ans: c 67. The materials are a bit inferior conductors of magnetic flux than air. (a) ferromagnetic (b) paramagnetic (c) diamagnetic (d) dielectric Ans: c 68. Hysteresis loop in case of magnetically hard materials is more in shape as compared to magnetically soft materials. (a) circular (b) triangular (c) rectangular (d) none of the above Ans: c 69. A rectangular magnet of magnetic moment M is cut into two piece of same length, the magnetic moment of each piece will be (a) M (6) M/2 (c) 2 M (d) M/4 Ans: b 70. A keeper is used to (a) change the direction of magnetic lines (b) amplify flux (c) restore lost flux (d) provide a closed path for flux Ans: d 71. Magnetic moment is a (a) pole strength (6) universal constant (c) scalar quantity (d) vector quantity Ans: d 72. The change of cross-sectional area of conductor in magnetic field will affect (a) reluctance of conductor (b) resistance of conductor (c) (a) and (b) b >th in the same way (d) none of the above Ans: c 73. The uniform magnetic field is (a) the field of a set of parallel conductors (b) the field of a single conductor (c) the field in which all lines of mag¬netic flux are parallel and equidis¬tant (d) none of the above Ans: c 74. The magneto-motive force is (a) the voltage across the two ends of exciting coil (b) the flow of an electric current (c) the sum of all currents embraced by one line of magnetic field (d) the passage of magnetic field through an exciting coil Ans: c 75. What will be the current passing through the ring shaped air cored coil when number of turns is 800 and ampere turns are 3200 ? (a) 2 (b) 4 (c) 6 (d) 8 Ans: b 76. What will be the magnetic potential difference across the air gap of 2 cm length in magnetic field of 200 AT/m ? (a) 2 AT (b) 4 AT (c) 6 AT (d) 10 AT Ans: b 77. Which of the following statements is correct ? (a) The magnetic flux inside an exciting coil is lower than its outside surface (6) The magnetic flux inside an exciting coil is zero (e) The magnetic flux inside the exciting coil is greater than its outside surface (d) The magnetic flux inside the exciting coil is same as on its outside surface Ans: d 78. A certain amount of current flows through a ring-shaped coil with fixed number of turns. How does the mag netic induction B varies inside the coil if an iron core is threaded into coil without dimensional change of coil ? (a) Decreases (b) Increases (c) Remains same (d) First increases and then decreases depending on the depth of iron in¬sertion Ans: b 79. The magnetic reluctance of a material (a) decreases with increasing cross sectional area of material (6) increases with increasing cross-sec-tional area of material (c) does not vary with increasing cross-sectional area of material (d) any of the above Ans: a 80. The initial permeability of an iron rod is (a) the highest permeability of the iron rod (b) the lowest permeability of the iron rod (c) the permeability at the end of the iron rod (d) the permeability almost in non-magnetised state Ans: d 82. How does the magnetic compass needle behave in a magnetic field ? (a) It assures a position right angle to magnetic field (b) It starts rotating (c) It assures a position which follows a line of magnetic flux (d) None of the above Ans: c 83. In a simple magnetic field the strength of magnet flux (a) is constant and has same value in energy part of the magnetic field (6) increases continuously from initial value to final value (c) decreases continuously from initial value to final value (d) first increases and then decreases till it becomes zero Ans: d 84. The stray line of magnetic flux is defined as (a) a line vertical to the flux lines (b) the mean length of a ring shaped coil (c) a line of magnetic flux in a non-uniform field (d) a line of magnetic flux which does not follow the designed path Ans: d 85. The bar magnet has (a) the dipole moment (b) monopole moment (c) (a) and (b) both (d) none of the above Ans: a 86. Which of the following materials are dia-magnetic ? (a) Silver (b) Copper (c) Silver and copper (d) Iron Ans: c 87. Which of the following type of materials are not very important for engineering applications ? (a) Ferromagnetic (b) Paramagnetic (c) Diamagnetic (d) None of the above Ans: c 88. The susceptibility of paramagnetic materials generally lies between (a) KT3 and 1CT6 (b) 1CT3 and 1CT7 (c) KT4 and KT8 (d) 10"2 and KT5 Ans: a 89. For which of the following materials the saturation value is the highest ? (a) Ferromagnetic materials (6) Paramagnetic materials (c) Diamagnetic materials (d) Ferrites Ans: d 90. The magnetic materials exhibit the property of magnetisation because of (a) orbital motion of electrons (b) spin of electrons (c) spin of nucleus (d) either of these (e) all of the above Ans: c 91. For which of the following materials the net magnetic moment should be zero ? (a) Diamagnetic materials (b) Ferrimagnetic materials (c) Antiferromagnetic materials (d) Antiferrimagnetic materials Ans: c 92. The attraction capacity of electromagnet will increase if the (a) core length increases i (b) core area increases (c) flux density decreases (d) flux density increases Ans: d 93. Which of the following statements is correct ? (a) The conductivity of ferrites is better than ferromagnetic materials (b) The conductivity of ferromagnetic materials is better than ferrites (c) The conductivity of ferrites is very high (d) The conductivity of ferrites is same as that of ferromagnetic materials Ans: a 96. Temporary magnets are used in (a) loud-speakers (b) generators (c) motors (d) all of the above Ans: d 97. Main causes of noisy solenoid are (a) strong tendency of fan out of lami-nations at the end caused by repul¬sion among magnetic lines of force (b) uneven bearing surface, caused by dirt or uneven wear between moving and stationary parts (c) both of above (d) none of the above Ans: c 99. Strength of an electromagnet can be increased by (a) increasing the cross-sectional area (b) increasing the number of turns (c) increasing current supply (d) all above methods Ans: 100. Core of an electromagnet should have (a) low coercivity (6) high susceptibility (c) both of the above (d) none of the above Ans: c 101. Magnetism of a magnet can be destroyed by (a) heating (b) hammering (c) by inductive action of another magnet (d) by all above methods Ans: d MAGNETIC CIRCUIT 1. An air gap is usually inserted in magnetic circuits to (a) increase m.m.f. (b) increase the flux (c) prevent saturation (d) none of the above Ans: c 2. The relative permeability of a ferromagnetic material is (a) less than one (b) more than one (c) more than 10 (d) more than 100 or 1000 Ans: d 3. The unit of magnetic flux is (a) henry (b) weber (c) ampereturn/weber (d) ampere/metre Ans: b 4. Permeability in a magnetic circuit corresponds to______ in an electric circuit. (a) resistance (b) resistivity (c) conductivity (d) conductance Ans: c 5. Point out the wrong statement. Magnetic leakage is undesirable in electric machines because it (a) lowers their power efficiency (b) increases their cost of manufacture (c) leads to their increased weight (d) produces fringing Ans: a 6. Relative permeability of vacuum is (a) 1 (b) 1 H/m (c) 1/4JI (d) 4n x 10-' H/m Ans: a 7. Permanent magnets are normally made of (a) alnico alloys (b) aluminium (c) cast iron (d) wrought iron Ans: a 8. Energy stored by a coil is doubled when its current is increased by percent. (a) 25 (b) 50 (c)41.4 (d) 100 Ans: c 9. Those magnetic materials are best suited for making armature and transformer cores which have____permeability and_______hystersis loss. (a) high, high (b) low, high (c) high, low (d) low, low Ans: c 10. The rate of rise of current through an inductive coil is maximum (a) at 63.2% of its maximum steady value (b) at the start of the current flow (c) after one time constant (d) near the final maximum value of current Ans: b 11. When both the inductance and resistance of a coil are doubled the value of (a) time constant remains unchanged (b) initial rate of rise of current is doubled (c) final steady current is doubled (d) time constant is halved Ans: a 12. The initial rate of rise of current through a coil of inductance 10 H when suddenly connected to a D.C. supply of 200 V is_______Vs (a) 50 (b) 20 (c) 0.05 (d) 500 Ans: b 13. A material for good magnetic memory should have (a) low hysteresis loss (b) high permeability (c) low retentivity (d) high retentivity Ans: d 14. Conductivity is analogous to (a) retentivity (b) resistivity (c) permeability (d) inductance Ans: c 15. In a magnetic material hysteresis loss takes place primarily due to (a) rapid reversals of its magnetisation (b) flux density lagging behind magnetising force (c) molecular friction (d) it high retentivity Ans: d 16. Those materials are well suited for making permanent magnets which have______retentivity and _______coercivity. (a) low, high (b) high, high (c) high, low (d) low, low Ans: b 17. If the area of hysteresis loop of a material is large, the hysteresis loss in this material will be (a) zero (b) small (c) large (d) none of the above Ans: c 18. Hard steel is suitable for making permanent magnets because (a) it has good residual magnetism (b) its hysteresis loop has large area (c) its mechanical strength is high (d) its mechanical strength is low Ans: a 19. Silicon steel is used in electrical machines because it has (a) low co-ercivity (b) low retentivity (c) low hysteresis loss (d) high co-ercivity Ans: c 20. Conductance is analogous to (a) permeance (b) reluctance (c) flux (d) inductance Ans: a 21. The property of a material which opposes the creation of magnetic flux in it is known as (a) reluctivity (b) magnetomotive force (c) permeance (d) reluctance Ans: d 22. The unit of retentivity is (a) weber (b) weber/sq. m (c) ampere turn/metre (d) ampere turn Ans: b 23. Reciprocal of reluctance is (a) reluctivity (b) permeance (c) permeability (d) susceptibility Ans: b 24. While comparing magnetic and electric circuits, the flux of magnetic circuit is compared with which parameter of electrical circuit ? (a) E.m.f. (b) Current (c) Current density (d) Conductivity Ans: b 25. The unit of reluctance is (a) metre/henry (b) henry/metre (c) henry (d) 1/henry Ans: d 26. A ferrite core has less eddy current loss than an iron core because (a) ferrites have high resistance (b) ferrites are magnetic (c) ferrites have low permeability (d) ferrites have high hysteresis Ans: d 27. Hysteresis loss least depends on (a) volume of material (b) frequency (c) steinmetz co-efficient of material (d) ambient temperature Ans: d 28. Laminated cores, in electrical machines, are used to reduce (a) copper loss (b) eddy current loss (c) hysteresis loss (d) all of the above Ans: b ELECTROMAGNETIC INDUCTION 1. The property of coil by which a counter e.m.f. is induced in it when the current through the coil changes is known as (a) self-inductance (b) mutual inductance (c) series aiding inductance (d) capacitance Ans: a 2. As per Faraday's laws of electromagnetic induction, an e.m.f. is induced in a conductor whenever it (a) lies perpendicular to the magnetic flux (b) lies in a magnetic field (e) cuts magnetic flux (d) moves parallel to the direction of the magnetic field Ans: c 3. Which of the following circuit element stores energy in the electromagnetic field ? (a) Inductance (b) Condenser (c) Variable resistor (d) Resistance Ans: a 4. The inductance of a coil will increase under all the following conditions except (a) when more length for the same number of turns is provided (6) when the number of turns of the coil increase (c) when more area for each turn is provided (d) when permeability of the core increases Ans: a 5. Higher the self-inductance of a coil, (a) lesser its weber-turns (b) lower the e.m.f. induced (c) greater the flux produced by it (d) longer the delay in establishing steady current through it Ans: d 6. In an iron cored coil the iron core is removed so that the coil becomes an air cored coil. The inductance of the coil will (a) increase (b) decrease (c) remain the same (d) initially increase and then decrease Ans: b 7. An open coil has (a) zero resistance and inductance (b) infinite resistance and zero inductance (c) infinite resistance and normal inductance (d) zero resistance and high inductance Ans: b 8. Both the number of turns and the core length of an inductive coil are doubled. Its self-inductance will be (a) unaffected (b) doubled (c) halved (d) quadrupled Ans: b 9. If current in a conductor increases then according to Lenz's law self-induced voltage will (a) aid the increasing current (b) tend to decrease the amount of cur-rent (c) produce current opposite to the in-creasing current (d) aid the applied voltage Ans: c 10. The direction of incViced e.m.f. can be found by (a) Laplace's law (b) Lenz's law (c) Fleming's right hand rule (d) Kirchhoff s voltage law Ans: b 11. Air-core coils are practically free from (a) hysteresis losses (b) eddy current losses (c) both (a) and (b) (d) none of the above Ans: c 12. The magnitude of the induced e.m.f. in a conductor depends on the (a) flux density of the magnetic field (b) amount of flux cut (c) amount of flux linkages (d) rate of change of flux-linkages Ans: d 13. Mutually inductance between two magnetically-coupled coils depends on (a) permeability of the core (b) the number of their turns (c) cross-sectional area of their com-mon core (d) all of the above Ans: d 14. A laminated iron core has reduced eddy-current losses because (a) more wire can be used with less D.C. resistance in coil (b) the laminations are insulated from each other (c) the magnetic flux is concentrated in the air gap of the core (d) the laminations are stacked vertf-cally Ans: b 15. The law that the induced e.m.f. and current always oppose the cause producing them is due to (a) Faraday (b) Lenz (c) Newton (d) Coulomb Ans: b 16. Which of the following is not a unit of inductance ? (a) Henry (b) Coulomb/volt ampere (c) Volt second per ampere (d) All of the above Ans: b 17. In case of an inductance, current is proportional to (a) voltage across the inductance (b) magnetic field (c) both (a) and (b) (d) neither (a) nor (b) Ans: b 18. Which of the following circuit elements will oppose the change in circuit current ? (a) Capacitance (b) Inductance (c) Resistance (d) All of the above Ans: b 19. For a purely inductive circuit which of the following is true ? (a) Apparent power is zero (b) Relative power is.zero (c) Actual power of the circuit is zero (d) Any capacitance even if present in the circuit will not be charged Ans: c 20. Which of the following is unit of inductance ? (a) Ohm (b) Henry (c) Ampere turns (d) Webers/metre Ans: b 21. An e.m.f. of 16 volts is induced in a coil of inductance 4H. The rate of change of current must be (a) 64 A/s (b) 32 A/s (c) 16 A/s (d) 4 A/s Ans: d 22. The core of a coil has a length of 200 mm. The inductance of coil is 6 mH. If the core length is doubled, all other quantities, remaining the same, the in ductance will be (a) 3 mH (b) 12 mH (c) 24mH (d)48mH Ans: a 23. The self inductances of two coils are 8 mH and 18 mH. If the co-efficients of coupling is 0.5, the mutual inductance of the coils is (a) 4 mH (b) 5 mH (c) 6 mH (d) 12 mH Ans: c 24. Two coils have inductances of 8 mH and 18 mH and a co-efficient of coupling of 0.5. If the two coils are connected in series aiding, the total inductance will be (a) 32 mH (b) 38 mH (c) 40 mH (d) 48 mH Ans: b 25. A 200 turn coil has an inductance of 12 mH. If the number of turns is increased to 400 turns, all other quantities (area, length etc.) remaining the same, the inductance will be (a) 6 mH (b) 14 mH (c) 24 mH (d) 48 mH Ans: d 26. Two coils have self-inductances of 10 H and 2 H, the mutual inductance being zero. If the two coils are connected in series, the total inductance will be (a) 6 H (b) 8 H (c) 12 H (d) 24 H Ans: c 27. In case all the flux from the current in coil 1 links with coil 2, the co-efficient of coupling will be (a) 2.0 (b) 1.0 (c) 0.5 (d) zero Ans: b 28. A coil with negligible resistance has 50V across it with 10 mA. The inductive reactance is (a) 50 ohms (b) 500 ohms (c) 1000 ohms (d) 5000 ohms Ans: d 29. A conductor 2 metres long moves at right angles to a magnetic field of flux density 1 tesla with a velocity of 12.5 m/s. The induced e.m.f. in the conductor will be (a) 10 V (6) 15 V (c) 25V (d) 50V Ans: c 30. Lenz's law is a consequence of the law of conservation of (a) induced current (b) charge (c) energy (d) induced e.m.f. Ans: c 31. A conductor carries 125 amperes of current under 60° to a magnetic field of 1.1 tesla. The force on the conductor will be nearly (a) 50 N (b) 120 N (c) 240 N (d) 480 N Ans: b 32. Find the force acting on a conductor 3m long carrying a current of 50 amperes at right angles to a magnetic field having a flux density of 0.67 tesla. (a) 100 N (b) 400 N (c) 600 N (d) 1000 N Ans: a 33. The co-efficient of coupling between two air core coils depends on (a) self-inductance of two coils only (b) mutual inductance between two coils only (c) mutual inductance and self inductance of two coils (d) none of the above Ans: c 34. An average voltage of 10 V is induced in a 250 turns solenoid as a result of a change in flux which occurs in 0.5 second. The total flux change is (a) 20 Wb (b) 2 Wb (c) 0.2 Wb (d) 0.02 Wb Ans: d 35. A 500 turns solenoid develops an average induced voltage of 60 V. Over what time interval must a flux change of 0.06 Wb occur to produce such a voltage ? (a) 0.01 s (b) 0.1 s (c) 0.5 s (d) 5 s Ans: c 36. Which of the fpllowing inductor will have the least eddy current losses ? (a) Air core (b) Laminated iron core (c) Iron core (d) Powdered iron core Ans: a 37. A coil induces 350 mV when the current changes at the rate of 1 A/s. The value of inductance is (a) 3500 mH (b) 350 mH (c) 250 mH (d) 150 mH Ans: b 38. Two 300 uH coils in series without mutual coupling have a total inductance of (a) 300 uH (b) 600 uH (c) 150 uH (d) 75 uH Ans: b 39. Current changing from 8 A to 12 A in one second induced 20 volts in a coil. The value of inductance is (a) 5 mH (b) 10 mH (c) 5 H (d) 10 H Ans: c 40. Which circuit element(s) will oppose the change in circuit current ? (a) Resistance only (b) Inductance only (c) Capacitance only (d) Inductance and capacitance Ans: b 41. A crack in the magnetic path of an inductor will result in (a) unchanged inductance (b) increased inductance (c) zero inductance (d) reduced inductance Ans: d 42. A coil is wound on iron core which carries current I. The self-induced voltage in the coil is not affected by (a) variation in coil current (b) variation in voltage to the coil (c) change of number of turns of coil (d) the resistance of magnetic path Ans: b 43. A moving magnetic field will produce the same effect as a conductor that is moving. (a) Yes (b) No Ans: 44. The polarity of the induced voltage can be determined by using the left-hand generator rule. (a) Yes (b) No Ans: a 45. Increasing the field or increasing the current will decrease the force on the conductor. (a) Yes (b) No Ans: b 46. Reversing the field or the current will reverse the force on the conductor. (a) Yes (b) No Ans: a 47. When a conductor moves in the field, so that it makes an angle 8 with the lines of flux, the force F is given as : F = Bl sin2 0. (a) Yes (b) No Ans: b 48. The self-inductance of the coil may be defined as equal to the e.m.f. induced in volts when the current in the circuit changes at the rate of unit weber turns. (a) Yes (b) No Ans: b GOVERNMENT COLLEGE OF ENGINEERING, BARGUR MEASUREMENTS AND INSTRUMENTATION OBJECTIVE TYPE QUESTIONS 1. The use of _____ instruments is merely confined within laboratories as stand¬ardizing instruments. (a) absolute (b) indicating (c) recording (d) integrating (e) none of the above Ans: a 2. Which of the following instruments indicate the instantaneous value of the electrical quantity being measured at the time at which it is being measured ? (a) Absolute instruments (b) Indicating instruments (c) Recording instruments (d) Integrating instruments Ans: b 3. _____ instruments are those which measure the total quantity of electricity delivered in a particular time. (a) Absolute (b) Indicating (c) Recording (d) Integrating Ans: d 4. Which of the following are integrating instruments ? (a) Ammeters (b) Voltmeters (c) Wattmeters (d) Ampere-hour and watt-hour meters Ans: d 5. Resistances can be measured with the help of (a) wattmeters (b) voltmeters (c) ammeters (d) ohmmeters and resistance bridges (e) all of the above Ans: d 6 According to application, instruments are classified as (a) switch board (b) portable (c) both (a) and (b) (d) moving coil (e) moving iron (f) both (d) and (e) Ans: c 7. Which of the following essential features is possessed by an indicating instrument ? (a) Deflecting device (b) Controlling device (c) Damping device (d) All of the above Ans: d 8. A _____ device prevents the oscillation of the moving system and enables the latter to reach its final position quickly (a) deflecting (b) controlling (c) damping (d) any of the above Ans: c 9. The spring material used in a spring control device should have the following property. (a) Should be non-magnetic (b) Most be of low temperature co-efficient (c) Should have low specific resistance (d) Should not be subjected to fatigue (e) All of the above Ans: e 10. Which of the following properties a damping oil must possess ? (a) Must be a good insulator (b) Should be non-evaporating (c) Should not have corrosive action upon the metal of the vane (d) The viscosity of the oil should not change with the temperature (e) All of the above Ans: e 11. A moving-coil permanent-magnet instrument can be used as _____ by using a low resistance shunt. (a) ammeter (b) voltmeter (c) flux-meter (d) ballistic galvanometer Ans: a 12. A moving-coil permanent-magnet instrument can be used as flux-meter (a) by using a low resistance shunt (b) by using a high series resistance (c) by eliminating the control springs (d) by making control springs of large moment of inertia Ans: c 13. Which of the following devices may be used for extending the range of instruments ? (a) Shunts (b) Multipliers (c) Current transformers (d) Potential transformers (e) All of the above Ans: e 14. An induction meter can handle current upto (a) 10 A (b) 30 A (c) 60 A (d) 100 A Ans: d 15. For handling greater currents induction wattmeters are used in conjunction with (a) potential transformers (b) current transformers (c) power transformers (d) either of the above (e) none of the above Ans: b 16. Induction type single phase energy meters measure electric energy in (a) kW (b) Wh (c) kWh (d) VAR (e) None of the above Ans: c 17. Most common form of A.C. meters met with in every day domestic and industrial installations are (a) mercury motor meters (b) commutator motor meters (c) induction type single phase energy meters (d) all of the above Ans: c 18. Which of the following meters are not used on D.C. circuits (a) Mercury motor meters (b) Commutator motor meters (c) Induction meters (d) None of the above Ans: c 19. Which of the following is an essential part of a motor meter ? (a) An operating torque system (b) A braking device (c) Revolution registering device (d) All of the above Ans: d 20. A potentiometer may be used for (a) measurement of resistance (b) measurement of current (c) calibration of ammeter (d) calibration of voltmeter (e) all of the above Ans: e 21 is an instrument which measures the insulation resistance of an electric circuit relative to earth and one another, (a) Tangent galvanometer (b) Meggar (c) Current transformer (d) None of the above Ans: b 22. The household energy meter is (a) an indicating instrument (b) a recording instrument (c) an integrating instrument (d) none of the above Ans: c 23. The pointer of an indicating instrument should be (a) very light (b) very heavy (c) either (a) or (b) (d) neither (a) nor (b) Ans: a 24. The chemical effect of current is used in (a) D.C. ammeter hour meter (b) D.C. ammeter (c) D.C. energy meter (d) none of the above Ans: a 25. In majority of instruments damping is provided by (a) fluid friction (b) spring (c) eddy currents (d) all of the above Ans: c 26. An ammeter is a (a) secondary instrument (b) absolute instrument (c) recording instrument (d) integrating instrument Ans: a 27. In a portable instrument, the controlling torque is provided by (a) spring (b) gravity (c) eddy currents (d) all of the above Ans: a 28. The disc of an instrument using eddy current damping should be of (a) conducting and magnetic material (b) non-conducting and magnetic material (c) conducting and non-magnetic material (d) none of the above Ans: c 29. The switch board instruments (a) should be mounted in vertical position (6) should be mounted in horizontal position (c) either (a) or (b) (d) neither (a) nor (b) Ans: a 30. The function of shunt in an ammeter is to (a) by pass the current (b) increase the sensitivity of the ammeter (c) increase the resistance of ammeter (d) none of the above Ans: a 31. The multiplier and the meter coil in a voltmeter are in (a) series (b) parallel (c) series-parallel (d) none of the above Ans: a 32. A moving iron instrument can be used for (a) D.C. only (b) A.C. only (c) both D.C. and A.C. Ans: c 33. The scale of a rectifier instrument is (a) linear (b) non-linear (c) either (a) or (b) (d) neither (a) nor (b) Ans: a 34. For measuring current at high frequency we should use (a) moving iron instrument (b) electrostatic instrument (c) thermocouple instrument (d) none of the above Ans: c 35. The resistance in the circuit of the moving coil of a dynamometer wattmeter should be (a) almost zero (b) low (c) high (d) none of the above Ans: c 36. A dynamometer wattmeter can be used for (a) both D.C. and A.C. (b) D.C. only (c) A.C. only (d) any of the above Ans: a 37. An induction wattmeter can be used for (a) both D.C. and A.C. (6) D.C. only (c) A.C. only (d) any of the above Ans: b 38. The pressure coil of a wattmeter should be connected on the supply side of the current coil when (a) load impedance is high (b) load impedance is low (c) supply voltage is low (d) none of the above Ans: a 39. In a low power factor wattmeter the pressure coil is connected (a) to the supply side of the current coil (b) to the load side of the current coil (c) in any of the two meters at connection (d) none of the above Ans: b 40. In a low power factor wattmeter the compensating coil is connected (a) in series with current coil (b) in parallel with current coil (c) in series with pressure coil (d) in parallel with pressure coil Ans: c 41. In a 3-phase power measurement by two wattmeter method, both the watt meters had identical readings. The power factor of the load was (a) unity (6) 0.8 lagging (c) 0.8 leading (d) zero Ans: a 42. In a 3-phase power measurement by two wattmeter method the reading of one of the wattmeter was zero. The power factor of the load must be (a) unity (b) 0.5 (c) 0.3 (d) zero Ans: b 43. The adjustment of position of shading bands, in an energy meter is done to provide (a) friction compensation (b) creep compensation (c) braking torque (d) none of the above Ans: a 44. An ohmmeter is a (a) moving iron instrument (b) moving coil instrument (c) dynamometer instrument (d) none of the above Ans: b 45. When a capacitor was connected to the terminal of ohmmeter, the pointer indicated a low resistance initially and then slowly came to infinity position. This shows that capacitor is (a) short-circuited (b) all right (c) faulty Ans: b 46. For measuring a very high resistance we should use (a) Kelvin's double bridge (b) Wheat stone bridge (c) Meggar (d) None of the above Ans: c 47. The electrical power to a meggar is provided by (a) battery (b) permanent magnet D.C. generator (c) AC. generator (d) any of the above Ans: b 48. In a meggar controlling torque is provided by (a) spring (b) gravity (c) coil (d) eddy current Ans: c 49. The operating voltage of a meggar is about (a) 6 V (b) 12 V (c) 40 V (d) 100 V Ans: d 50. Murray loop test can be used for location of (a) ground fault on a cable (b) short circuit fault on a cable (c) both the ground fault and the short-circuit fault (d) none of the above Ans: c 51. Which of the following devices should be used for accurate measurement of low D.C. voltage ? (a) Small range moving coil voltmeter (b) D.C. potentiometer (c) Small range thermocouple voltmeter (d) None of the above Ans: b 52. It is required to measure the true open circuit e.m.f. of a battery. The best device is (a) D.C. voltmeter (b) Ammeter and a known resistance (c) D.C. potentiometer (d) None of the above Ans: c 53. A voltage of about 200 V can be measured (a) directly by a D.C. potentiometer (b) a D.C. potentiometer in conjunction with a volt ratio box (c) a D.C. potentiometer in conjunction with a known resistance (d) none of the above Ans: b 54. A direct current can be measured by (a) a D.C. potentiometer directly (b) a D.C. potentiometer in conjunction with a standard resistance (c) a D.C. potentiometer in conjunction with a volt ratio box (d) none of the above Ans: b 55. To measure a resistance with the help of a potentiometer it is (a) necessary to standardise the potentiometer (b) not necessary to standardise the potentiometer (c) necessary to use a volt ratio box in conjunction with the potentiometer (d) none of the above Ans: b 56. A phase shifting transformer is used in conjunction with (a) D.C. potentiometer (b) Drysdale potentiometer (c) A.C. co-ordinate potentiometer (d) Crompton potentiometer Ans: b 57. Basically a potentiometer is a device for (a) comparing two voltages (b) measuring a current (c) comparing two currents (d) measuring a voltage (e) none of the above Ans: a 58. In order to achieve high accuracy, the slide wire of a potentiometer should be (a) as long as possible (b) as short as possible (c) neither too small not too large (d) very thick Ans: a 59. To measure an A. C. voltage by using an A.C. potentiometer, it is desirable that the supply for the potentiometer in taken (a) from a source which is not the same as the unknown voltage (b) from a battery (c) from the same source as the unknown voltage (d) any of the above Ans: c 60. The stator of phase shifting transformer for use in conjunction with an A.C. potentiometer usually has a (a) single-phase winding (b) two-phase winding (c) three-phase winding (d) any of the above Ans: b 61. In an AC. co-ordinate potentiometer, the currents in the phase and quadrature potentiometer are adjusted to be (a) out of phase by 90° (6) out of phase by 60° (c) out of phase by 30° (d) out of phase by 0° (e) out of phase by 180° Ans: a 62. A universal RLC bridge uses (a) Maxwell bridge configuration for measurement of inductance and De Santas bridge for measurement of capacitance (b) Maxwell Wein bridge for measurement of inductance and modified De Santy's bridge for measurement of capacitance (c) Maxwell Wein bridge for measurement of inductance and Wein bridge for measurement of capacitance (d) Any of the above. Ans: b 63. For measurements on high voltage capacitors, the suitable bridge is (a) Wein bridge (b) Modified De Santy's bridge (c) Schering bridge (d) Any of the above (e) None of the above Ans: c 64. In an Anderson bridge, the unknown inductance is measured in terms of (a) known inductance and resistance (b) known capacitance and resistance (c) known resistance (d) known inductance Ans: b 65. Wagner earthing device is used to eliminate errors due to (a) electrostatic coupling (b) electromagnetic coupling (c) both (a) and (b) (d) none of the above Ans: a 66. For measurement of mutual inductance we can use (a) Anderson bridge (b) Maxwell's bridge (c) Heaviside bridge (d) Any of the above Ans: c 67. For measurement of inductance having high value, we should use (a) Maxwell's bridge (b) Maxwell Wein bridge (c) Hay's bridge (d) Any of the above Ans: c 68. If the current in a capacitor leads the voltage by 80°, the loss angle of the capacitor is (a) 10° (b) 80° (c) 120° (d) 170° Ans: a 69. In a Schering bridge the potential of the detector above earth potential is (a) a few volts only (6) 1 kV (c) 5 kV (d) 10 kV Ans: a 70. To avoid the effect of stray magnetic field in A.C. bridges we can use (a) magnetic screening (b) Wagner earthing device (c) wave filters (d) any of the above Ans: a 71. If an inductance is connected in one arm of bridge and resistances in the remaining three arms (a) the bridge can always be balanced (b) the bridge cannot be balanced (c) the bridge can be balanced if the resistances have some specific values Ans: b 72. A power factor meter has (a) one current circuit and two pres¬sure circuits (b) one current circuit and one pressure circuit (c) two current circuits and one pres¬sure circuit (d) none of the above Ans: a 73. The two pressure coils of a single phase power factor meter have (a) the same dimensions and the same number of turns (b) the same dimension but different number of turns (c) the same number of turns but different dimensions (d) none of the above Ans: a 74. In a single phase power factor meter the phase difference between the currents in the two pressure coils is (a) exactly 0° (b) approximately 0° (c) exactly 90° (d) approximately 90° Ans: c 75. In a dynamometer 3-phase power factor meter, the planes of the two moving coils are at (a) 0° (b) 60° (c) 90° (d) 120° Ans: d 76. In a vibrating reed frequency meter the natural frequencies of two adjacent reeds have a difference of (a) 0.1 Hz (b) 0.25 Hz (c) 0.5 Hz (d) 1.5 Hz Ans: c 77. In a Weston frequency meter, the magnetic axes of the two fixed coils are (a) parallel (b) perpendicular (c) inclined at 60° (d) inclined at 120° Ans: b 78. A Weston frequency meter is (a) moving coil instrument (b) moving iron instrument (c) dynamometer instrument (d) none of the above Ans: b 79. A Weston synchronoscope is a (a) moving coil instrument (b) moving iron instrument (c) dynamometer instrument (d) none of the above Ans: c 80. In a Weston synchronoscope, the fixed coils are connected across (a) bus-bars (b) incoming alternator (c) a lamp (d) none of the above Ans: b 81. In Weston synchronoscope the moving coil is connected across (a) bus-bars (b) incoming alternator (c) fixed coils (d) any of the above Ans: a 82. The power factor of a single phase load can be calculated if the instruments available are (a) one voltmeter and one ammeter (b) one voltmeter, one ammetqr and one wattmeter (c) one voltmeter, one ammeter and one energy meter (d) any of the above Ans: b 83. The desirable static characteristics of a measuring system are (a) accuracy and reproducibility (b) accuracy, sensitivity and reproducibility (c) drift and dead zone (d) static error Ans: b 84. The ratio of maximum displacement deviation to full scale deviation of the instrument is called (a) static sensitivity (b) dynamic deviation (c) linearity (d) precision or accuracy Ans: c 85. Systematic errors are (a) instrumental errors (b) environmental errors (c) observational errors (d) all of the above Ans: d 86. Standard resistor is made from (a) platinum (b) maganin (c) silver (d) nichrome Ans: b 87. Commonly used standard capacitor is (a) spherical type (b) concentric cylindrical type (c) electrostatic type (d) multilayer parallel plate type Ans: b 88. Operating torques in analogue instruments are (a) deflecting and control (b) deflecting and damping (c) deflecting, control and damping (d) vibration and balancing Ans: c 89. Commonly used instruments in power system measurement are (a) induction (b) moving coil or iron (c) rectifier (d) electrostatic Ans: a 90. Damping of the Ballistic galvanometer is made small to (a) get first deflection large (b) make the system oscillatory (c) make the system critically damped (d) get minimum overshoot Ans: a 91. If an instrument has cramped scale for larger values, then it follows (a) square law (b) logarithmic law (c) uniform law (d) none of the above Ans: b 92. Volt box is a component to (a) extend voltage range (6) measure voltage (c) compare voltage in a box (d) none of the above Ans: a 93. E.m.f. of a Weston cell is accurately measured by (a) electrostatic voltmeter (b) hot wire voltmeter (c) isothermal voltmeter (d) electrodynamic voltmeter Ans: a 94. The gravity controlled instrument has crowded scale because current is proportional to (a) balancing weight (b) deflection angle (c) sine of deflection angle Ans: c 95. A sensitive galvanometer produces large deflection for a (a) small value of current (b) large value of current (c) large value of power (d) large value of voitage (e) none of the above Ans: a 96. A multirangq instrument has (a) multiple shunt or series resistances inside the meter (b) multicoii arrangement (c) variable turns of coil (d) multi range meters inside the measurement system (e) any of the above Ans: a 97. The rectifier instrument is not free from (a) temperature error (b) wave shape error (c) frequency error (d) all of the above Ans: c 98. Alternating current is measured by (a) induction ammeter (b) permanent magnet type ammeter (c) electrostatic ammeter (d) moving iron repulsion type voltmeter Ans: a 99. Most sensitive galvanometer is (a) elastic galvanometer (b) vibration galvanometer (c) Duddlb galvanometer (d) spot ballistic galvanometer Ans: d 100. Instrument transformers are (a) potential transformers (b) current transformers (c) both (a) and (b) (d) power transformers Ans: c 101. An instrument transformer is used to extend the range of (a) induction instrument (b) electrostatic instrument (c) moving coil instrument (d) any of the above Ans: a 102. Wattmeter cannot be designed on the principle of (a) electrostatic instrument (b) thermocouple instrument (c) moving iron instrument (d) electrodynamic instrument Ans: c 103. In an energymeter braking torque is produced to (a) safe guard it against creep (b) brake the instrument (c) bring energy meter to stand still (d) maintain steady speed and equal to driving torque Ans: d 104. Various adjustments in an energy meter include (a) light load or friction (b) lag and creep (c) overload and voltage compensation (d) temperature compensation (e) all of the above Ans: e 105. The power of a n-phase circuit can be measured by using a minimum of (a) (n - 1) wattmeter elements (b) n wattmeter elements (c) (n + 1) wattmeter elements (d) 2n wattmeter elements Ans: a 106. Two holes in the disc of energymeter are drilled at the opposite sides of the spindle to (a) improve its ventilation (b) eliminate creeping at no load (c) increase its deflecting torque (d) increase its braking tcrque Ans: b 107. Which of the following is measured by using a vector voltmeter ? (a) Amplifier gain and phase shift (b) Filler transfer functions (c) Complex insersion loss (d) All of the above Ans: d 108. The principle on which vector voltmeter is based is (a) that it works on the principle of complex variation (b) that it measures the response of linear ramp voltage (c) same as digital meter (d) that it measures the amplitude of a single at two points and at the same time measures their phase difference Ans: d 109. To measure radio frequency, the suitable frequency meter is (a) Weston frequency meter (b) reed vibrator frequency meter (c) hetrodyne frequency meter (d) electrical resonance frequency meter Ans: c