Q 1 (A) (B) Q 2 (A) (B) (B) Q 3 (A) (B) Q 3 (A) (B) Q 4 (A) (B) Q 4 (A) (B) Q 5 (A) (B) Q 5 (A) (B) Q 1 (A) (B) Q 2 (A) (B) (B) Q 3 (A) (B) Q 3 (A) (B) Q 4 (A) (B) Q 4 (A) (B) Q 5 (A) (B) Q 5 (A) (B) Q 1 (A) (B) Q 2 (A) (B) (B) Q 3 (A) (B) Q 3 (A) (B) Q 4 (A) (B) Q 4 (A) (B) Q 5 (A) (B) Q 5 (A) (B) Q 1 (A) (B) Q 2 (A) (B) (B) Q 3 (A) (B) Q 3 (A) (B) Q 4 (A) (B) Q 4 (A) (B) Q 5 (A) (B) Q 5 (A) (B) . What are the various methods of neutral grounding? Explain any two. Draw di With help of circuit & phasor diagram explain resonant grounding method. What is importance of one line diagram of a power system? How it is drawn? Explain the importance of bus impedance matrix in fault calculation. Draw zero sequence networks for this system. An unloaded star connected solidly grounded 10 MVA. The transformer ratings. The resistance and reactanc A four bus sample power system is shown in fig 1. Vb = 320/_1900.Calculate the fault current at bus no 4 for three phase solid fault occurring at tha Discuss the effect of change in excitation of synchronous machine.u. The line is connected to generating station bus bars t Derive an expression for the fault current for a single line-to ground fault asan unloaded generator. Derive the necessary equations to convert: (i) phase quantities into symmetrical com A 50 MVA. 20kV has X1 = X2 = 20% and X0 = 5%. Determine the symmetrical com Write a brief note on phase shift of symmetrical components in Y-Δ transformer banks. Explain how fault current can be calculated when L-G fault occur through a fault impedance Zf. A three phase 50 Hz transmission line is 150 Km long and delivers 25 MW at 110KV at 0. The fault currents were: 3-Ф fault 1870A. Fig. The currents in three phase unbalance system are IR=(12+j6) A. 11 kV.85 p.f. A generator rated 100 MVA. find the sending end voltage and voltage regulation of a 250 km. State the factors on which corona loss depends. Explain the zero sequence impedance of transformer for various connections. The gen Derive an expression for the fault current for a double-line fault as an unloaded generator. 13. The three phase 220KV. Give reasons for following: 1.32 ohms. Draw the equivalent network of uniform long line and derive its π model. The system data is as under. generator rating. 50 Hz transmission line deli The voltage across a 3-phase unbalanced load are Va =200/_400. Derive expression for refraction and reflection coefficients. line to lin Draw a general circuit which can be used to determine zero sequence network of a two-winding transformer.2 KV alternator with solidly grounded neutral has a sub transient reactance of 0. Its neutral is grounded through a reactor of 0. A 100 MVA. transient and sub transient reactance of a synchronous machine. Vc=480/_3400. 50 Hz line is 250 Km long consisting of 22. Explain steady state. . Calculate. negative and zero sequence impedances are j1 Write a brief note on selection of circuit breaker. The generator is connected to the motors through transmission How the circuit breaker is selected for any particular location. Why it is necessary to earth neutral? Explain the difference between resistance and reactance grounding. Using the nominal π method. The phase sequence is RYB. 11KV generator has positive. 20kV has X1 = X2 = 20% and X0 = 5%.25 p. lagging. Explain single and double frequency transient.26mm diameter conductor spaced in a 6 mt delta configuration.. IB = (-15+j10) A. line impedance and load impe What is an equivalent π and equivalent T circuit of a long transmission line? Derive expression of parameters of these circuits in ter A 300 km 132 kV 3-phase overhead line has a total series impedance of 52+j200 Ω/phase and a total shunt admittance of j1. Its neutral is grounded through a reactor of 0. the negative and zero seque Explain how corona affects the electrical design of transmission line.(A) shows a power system network.32 ohms.IY=(12.j12) A.5 X 10 Find the disruptive critical voltage and visual corona voltage (local as well as general corona) for a 3-phase 220 kV line consisting of Discuss principle of symmetrical components. 33 KV three phase generator has a reactance of 15%. A 25 MVA. Generator (G1) Derive the double line to ground fault in a 3 phase alternator. dra A 33 KV line has a resistance of 4 ohm and reactance of 16 ohm respectively.3-phase.Quastion asked in papers What is importance of receiving end power circle diagram? Explain the steps of constructing it. The gen Discuss the phenomenon of wave reflection and wave refraction. A generator rated 100 MVA. Using this circuit. Discuss the behavior of a travelling wave when it reaches the end of (i) open circuited (ii) short circuited transmission line. 3-phase alternator was subjected to different types of faults. The analysis of unsymmetrical faults can be more easily done with the help of symmetrical compone Figure 1 shows the single line diagram of a simple system. 50 Hz frequency.u. The line has co Derive the ABCD constants for medium transmission line using Nominal Π representation.2 KV What is P.9 p. The load on the line is 125 MW at 215 kv with 100% power factor. Find the v Derive the expressions of positive. The current flowing to the Δ Connected load through line “a” is 10 A. Explain need of neutral grounding using phasor diagrams. Also discuss the measures taken to control corona in EHVAC transmission lines. System. Starting from the first principles.A synchronous generator and a synchronous motor each rated 25MVA. Write a note on zero sequence networks in brief. U.8 KV generator with Xd ’’ = 15% is connected through a transformer to a bus which supplies four identical mot Enlist the methods of neutral grounding. system? Explain the advantages of P. Explain the phenomena of arcing grounds. The generator supplies a number of synchronous motors ov What is characteristic impedance? Derive the expressions of VR and IR at any point of line as a function of distance X from the A single circuit 60 Hz transmission line is 370 km long. 11KV having 15% subtransient reactance are connected th Discuss the advantages of per unit computations. with the current Explain traveling and reflecting waves on transmission line with open end at the receiving . Find (1) Ohmic value of reactance of t Explain travelling waves of a transmission line when the receiving end is shortcircuited. Its star connected winding has a reactance of 0. A 300 MVA 20 KV 3 Φ generator has a subtransient reactance of 20 %. The three phase ratings of a three winding transformer are: Primary Y Connected. 15 MVA. Also write the expressions for voltage re Derive the expression for real power PR and reactive power QR at receiving end of a medium transmission line in terms of tr Explain the Equivalent Circuit model of Synchronous machine. 33 KV. 66 KV. Explain any one of the method in detail. derive Vt = Ef – Ia (Ra+ jXs) Where Xs = X With the help of neat phasor diagram. Secondary Y Connected. Explain any one method of neutral grounding. show that surges behaves as travelling waves. A generator is rated 1000 MVA. negative and zero sequence voltage components in terms of given set of unbalance voltage pha One conductor of a three phase line is open. From the first principal. U. A 25 MVA 13. explain the operation of synchronous generator for different field excitation. 13. Find expression for surge impedance and wave velo Discuss factors affecting corona. Find the critical disruptive voltage and corona loss for a 3 phase line which is operating at 220 KV. Explain the phenomena of sudden three phase short circuit at the generator terminal on no load condition and define sub transien . How does neutral grounding eliminate the arcing ground? Also enlist the advantages of Explain the phenomena of corona. paper of chepter no. 1 1 3 2 2 3 3 3 3 4 5 5 5 6 6 7 8 book 3 1 1 6 4 5 4 3 5 5 5 5 8 7 8 7 1 1 4 4 4 5 5 3 .3.6 May-13 May-13 May-13 May-13 May-13 May-13 May-13 May-13 May-13 May-13 May-13 May-13 May-13 May-13 May-13 May-13 Jun-12 Jun-12 Jun-12 Jun-12 Jun-12 Jun-12 Jun-12 Jun-12 page no. Jan-13 Jan-13 Jan-13 Jan-13 Jan-13 Jan-13 Jan-13 Jan-13 Jan-13 Jan-13 Jan-13 Jan-13 Jan-13 Jan-13 Jan-13 Jan-13 Jan-13 May-13 5. Jun-12 Jun-12 Jun-12 Jun-12 Jun-12 Jun-12 Jun-12 Jun-12 Jun-12 Nov-11 Nov-11 Nov-11 Nov-11 Nov-11 Nov-11 Nov-11 Nov-11 Nov-11 Nov-11 Nov-11 Nov-11 Nov-11 Nov-11 Nov-11 Nov-11 Nov-11 3 2 3 8 4 7 8 6 6 1 1 2 2 2 2 3 1 1 4 4 8 3 7 7 6 3 . Q 1 (A) Derive the ABCD constants for medium transmission line using Nominal Π representation. (B) A three phase 50 Hz transmission line is 150 Km long and delivers 25 MW at 110KV at 0. The line is supplying 40 MVA at 0. The line conductors are spaced equilaterally 3 m apart.5 X 10-3 siemens per phase to neutral. The conductor resistance is 0. current.020 Ω⁄km and y=3.85 p.6 cm. The line charging admittance is 0.3×10-6 ʊ /km/phase. (B) Derive the expression for real power PR and reactive power QR at receiving end of a medium paper of Jan-13 Jan-13 May-13 May-13 Jun-12 Jun-12 Nov-11 Nov-11 Nov-11 transmission line in terms of transmission line constants (ABCD Constants) Q 3 (A) What is characteristic impedance? Derive the expressions of VR and IR at any point of line as a function of distance X from the receiving end using distributed parameters. lagging at 132 kV.PSAs : Questions from Ch-1 Current and Voltage Relations on a Transmission Line Quastion asked in papers Q 1 (A) What is importance of receiving end power circle diagram? Explain the steps of constructing it.f. (Given z=0.9 Ω respectively.5239 79.3-phase. The resistance and reactance of the line per conductor per kilometer are 0. Q 1 (A) Draw the equivalent network of uniform long line and derive its π model.f.8 p. 50 Hz transmission line delivering 25 MVA at 0. Find the voltage. current and power at sending end and voltage regulation of the line. power factor and power. (B) Using the nominal π method. (B) A 300 km 132 kV 3-phase overhead line has a total series impedance of 52+j200 Ω/phase and a total shunt admittance of j1. Also write the expressions for voltage regulation and efficiency for the same line.8 powerfactor (lagging) to a balanced load at 132 kv.17 Χ 10-6 900 mho⁄km Nov-11 . find the sending end voltage and voltage regulation of a 250 km.11 ohm/km and its effective diameter is 1. Neglect leakages. The load on the line is 125 MW at 215 kv with 100% power factor. Compute the voltage regulation and transmission efficiency by applying nominal π method. lagging. Q 2 (A) What is an equivalent π and equivalent T circuit of a long transmission line? Derive expression of parameters of these circuits in terms of line parameters. Using long line equations find sending end voltage. (B) A single circuit 60 Hz transmission line is 370 km long.3 Ω and 0. 5 MVA. 10 MVA. From the first principal. 66 KV in the primary circuit. the leakage impedances are Zps= 7% on 15 MVA 66 KV Base. Tertiary Δ Connected. Jun-12 Explain the Equivalent Circuit model of Synchronous machine. System. Neglecting resistance. 2. Also derive the expressions you use.2 KV. 15 MVA. (B) (B) Q 4 (A) Q 2 (A) . U. Nov-11 Nov-11 Q 3 (A) What is P. system? Explain the advantages of P. Jan-13 What is importance of one line diagram of a power system? How it is drawn? Discuss the advantages of per unit computations.3 KV. Also draw the equivalent circuit diagram. 66 KV.2 KV Base Find the per unit impedances of the star connected equivalent circuit for a base of 15 MVA. Nov-11 (B) The three phase ratings of a three winding transformer are: Primary Y Connected. U. explain the operation of synchronous generator for different field excitation. Zpt= 9% on 15 MVA 66 KV Base. 13. Secondary Y Connected. Zst= 10% on 10 MVA 13. derive V t = Ef – Ia (Ra+ jXs) Where Xs = Xar + Xl.PSAs : Questions from Ch-2 System Modeling Quastion asked in papers paper of Jan-13 Discuss the effect of change in excitation of synchronous machine. Nov-11 (B) With the help of neat phasor diagram. 33 KV.9 KV with a leakage reactance of 10%.20 pu.10 pu. value of reactance of generator winding on the specified base. x’g1=0. generator rating. G2:11. (B) Figure 1 shows the single line diagram of a simple system. 230/20 KV with leakage reactance of 10%. for the fault specified. line impedance and load impedance are shown. The transformer s are rated 25 MVA. XT1=0.000 KVA with 10% reactance and 5000 KVA with 5% reactance. transient and steady state reactances of synchronous generator.10 pu.9 p. (B) A synchronous generator and a synchronous motor each rated 25MVA.PSAs : Questions from Ch-3 Symmetrical Three-Phase Faults Quastion asked in papers paper of Q 2 (A) A four bus sample power system is shown in fig 1. Jan-13 (B) Explain steady state.8/6. Select the generator rating as base in the generator circuit.10 pu.100MVA. Transformer T2 is composed of three single phase transformers each rated 127/13. Jan-13 Jan-13 Q 3 (A) How the circuit breaker is selected for any particular location. motor and fault. Find the subtransient current in the generator.100 MVA. The bus voltage at the motors is 6. line current. Carry out the calculation in p. (B) A 25 MVA 13. terminals of the transformers and at the load end of the line. as shown in fig.08 pu T1:11/110KV.U.v.0 pu and pre fault current be zero. Draw impedance diagram.2kv. Jun-12 (B) A 300 MVA 20 KV 3 Φ generator has a subtransient reactance of 20 %. Line from 1 to 2=0. Its star connected winding has a reactance of 0. Find actual value of generator current.08 pu. Line from 1 to 3 =0. May-13 (B) A 33 KV line has a resistance of 4 ohm and reactance of 16 ohm respectively. (B) Explain the phenomena of sudden three phase short circuit at the generator terminal on no load condition and define sub transient. 100 MVA with leakage reactance of 10%. Line from 2 to 4=0.u. The three phase rating of the transformer is 25 MVA 13. Line from 1 to 4=0. diagram. load voltage and load power. Determine (a) the subtransient current in the fault. 66 KV. all rated 13. u.2 KV. Jun-12 (B) A generator is rated 1000 MVA.8 KV generator with Xd ’’ = 15% is connected through a transformer to a bus which supplies four identical motors as shown in Fig.Calculate the fault current at bus no 4 for three phase solid fault occurring at that bus. load current.9 kv when a three phase fault occurs at the point P. (b) the subtransient current in breaker A. The line is connected to generating station bus bars through a 6000 KVA step up transformer which has a reactance of 6%.20 pu.06 pu T2: 11/110KV. transient and sub transient reactance of a synchronous machine. Motors have rated inputs of 40MVA. 11KV having 15% subtransient reactance are connected through transformer and a line as shown in fig. Assume pre fault voltage as 1. The three phase transformer T1 us rated 350MVA.2 KV.u.5 Ω⁄km Draw the reactance diagram with all the reactances marked in per unit. XT2=0. The line has a reactance of 10% on a base of 25 MVA. The neutral of the second motor M 2 is not grounded. neglecting phase shift in transformer. 6.8 powerfactor leading and a terminal voltage of 10. The generator is connected to the motors through transmission line and a transformer as shown in fig 2. x’g2=0. Rated inputs to the motors are 200 MVA and 100MVA for M1 and M2 respectively. The generator supplies a number of synchronous motors over a 64 km transmission line having transformers at both ends.2 KV are represented by just two equivalent motors. The neutral of one motor M1 is grounded through reactance.9 KV. 22KV (2) The p. (B) A 100 MVA.phase fault occurs at the motor terminals. The motors. Find (1) Ohmic value of reactance of the winding if the generator is working in a circuit for which the bases are specified as 250MVA. For both motors X’’ = 20%.06 pu Jan-13 Jan-13 Q 3 (A) Explain the importance of bus impedance matrix in fault calculation. 11/66KV and 66/11 KV with leakage reactance of 10% each. The station has two generators rated 10. Various data are given below. Series reactance of the transmission line is 0.(B). The subtransient reactance Xd ’’ of each motor is 20% on a base of 5MVA. Draw the P. Line from 2 to 3=0. Nov-11 Nov-11 Nov-11 . G1:11. (See figure 2) May-13 Jun-12 Q 3 (A) Write a brief note on selection of circuit breaker. 30 MVA. The motor is drawing 15 MW at 0. The transformer ratings. 33 KV three phase generator has a reactance of 15%. Calculate the fault current and short circuit KVA when a 3-phase fault occurs at the h.100MVA. and 20 MVA at 30 KV with 20 % reactance each.100 MVA.6 KV when a symmetrical three. find the symmetrical components of the line currents. (ii) delta-delta transformer.(A) shows a power system network. Also prove that the transformation used is power invariant. Derive the necessary equations to convert: (i) phase quantities into symmetrical components (ii) symmetrical components in to phase quantities.PSAs : Questions from Ch-4 Symmetrical Components Quastion asked in papers paper of Jan-13 Q 4 (A) Explain the zero sequence impedance of transformer for various connections. Nov-11 . Q 3 (A) Discuss principle of symmetrical components. Transformer (T2): 30 MVA.u.09 p. 11/220 KV. with the current in line “a” as reference and assuming that line “c” is open. May-13 Q 2 (A) The voltage across a 3-phase unbalanced load are Va =200/_400. Zero sequence reactance of line is 555. X0 =0. (iii) star-star transformer with star point grounded. Nov-11 (B) One conductor of a three phase line is open.u. Transformer (T1): 50 MVA. 11KV. May-13 Q 3 (A) Draw a general circuit which can be used to determine zero sequence network of a two-winding transformer.08 p. The system data is as under. Vb = 320/_1900. Generator (G2) : 30 MVA. Phase sequence is abc.u.07 p. Vc=480/_3400. X0 =0. (B) Fig. Using this circuit. Q 4 (A) Derive the expressions of positive. Generator (G1): 50 MVA. Vb and Vc.u. Draw zero sequence networks for this system. X0 =0. 220/11 KV. negative and zero sequence voltage components in terms of given set of unbalance voltage phasors Va. Determine the symmetrical components of voltages.1 p. draw the zero sequence networks for (i) delta-star transformer with star point grounded. X0 =0.6 Ω Jun-12 Jun-12 (B) Write a note on zero sequence networks in brief. Jun-12 Jun-12 (B) Write a brief note on phase shift of symmetrical components in Y-Δ transformer banks. 11KV. The current flowing to the Δ Connected load through line “a” is 10 A. 13.2 KV alternator with solidly grounded neutral has a sub transient reactance of 0. negative and zero sequence component of current. Q 4 (A) Derive an expression for the fault current for a double-line fault as an unloaded generator. Q 4 (A) Derive an expression for the fault current for a single line-to ground fault asan unloaded generator. (1) Calculate the fault current. positive. R Y B paper of Jan-13 Q 4 (A) Explain how fault current can be calculated when L-G fault occur through a fault impedance Z . Its neutral is grounded through a reactor of 0. (B) A 50 MVA. Jan-13 May-13 May-13 May-13 May-13 May-13 Jun-12 Jun-12 . The fault currents were: 3-Ф fault 1870A. Find the fault current when (1) a single line to ground fault occurs at the terminals of an unloaded alternator (2) a L-L fault occurs. Find the sub-transient current in the faulted phase and line to line voltages. f Jan-13 (B) A 25 MVA. 11 kV.u. j0.4 Ω respectively. The generator is operating at rated voltage with load and is disconnected from the system when a single line to ground fault occurs at its terminals.u. The phase sequence is RYB. Calculate.8 Ω. (Repetition of example Q-4 for line to line fault). 20kV has X1 = X2 = 20% and X0 = 5%.PSAs : Questions from Ch-5 Unsymmetrical Faults Quastion asked in papers (B) The currents in three phase unbalance system are I =(12+j6) A. The alternator neutral is solidly grounded.j12) A. I = (-15+j10) A.35 and 0. Its neutral is grounded through a reactor of 0. negative and zero sequence impedances are j1.32 ohms. Q 3 (A) Derive the double line to ground fault in a 3 phase alternator.I =(12. Find the subtransient current in the faulted phase and line to line voltages. 11KV generator has positive. The generator is operating at rated voltage with load and is disconnected from the system when a line to line fault occurs at its terminals..32 ohms. Find pu values of the three sequences reactance of the alternator. 20kV has X1 = X2 = 20% and X0 = 5%. the negative and zero sequence reactances are 0. single line to ground fault 4130 A. (2) Determine the value of the inductive reactance that must be inserted at the generator neutral to limit the fault current to 50% of the value obtained in (1). (B) A generator rated 100 MVA.1 p.25 p. line to line fault 2590 A. 3-phase alternator was subjected to different types of faults.3 Ω. and j0. (B) A generator rated 100 MVA. (B) An unloaded star connected solidly grounded 10 MVA. A single line to ground fault occurs at the terminals of the generator. respectively. Q 5 (A) Discuss factors affecting corona.5 cm diameter arranged in a 3 meter delta connection. irregularity factor for local corona 0. irregularity factor for general corona 0. surface factor 0. Temperature 250 C. Assume air density factor of 1. pressure 73 cm of (B) mercury. The following data can be assumed: Temperature 25° C.84.84. pressure 73 cm of mercury. Explain the phenomena of corona. 50 Hz line is 250 Km long consisting of 22. The following data can be assumed. and irregularity factor for general (decided) corona 0. surface factor 0.1 KV/cm.72. The three phase 220KV. 50 Hz frequency. The line has conductor of 1. State the factors on which corona Q 5 (A) loss depends.26mm diameter conductor spaced in a 6 mt delta configuration.PSAs : Questions from Ch-6 Corona Quastion asked in papers Explain how corona affects the electrical design of transmission line.72 . irregularity factor for local corona 0. paper of Jan-13 Jan-13 Find the disruptive critical voltage and visual corona voltage (local as well as general corona) for a 3(B) phase 220 kV line consisting of 22.05 and dielectric strength of air to be 21. May-13 Jun-12 Jun-12 Nov-11 Q 5 (A) .26 mm diameter conductors spaced in a 6 m delta configuration.82. (B) Find the critical disruptive voltage and corona loss for a 3 phase line which is operating at 220 KV.82. Find the total loss in fair weather using Peek’s formula. Also discuss the measures taken to control corona in EHVAC transmission lines. PSAs : Questions from Ch-7 Neutral Grounding Quastion asked in papers paper of Jan-13 Q 5 (A) What are the various methods of neutral grounding? Explain any two. (B) Why it is necessary to earth neutral? Explain the difference between resistance and reactance grounding. Explain any one of the method in detail. Q 5 (A) Explain need of neutral grounding using phasor diagrams. (B) Explain the phenomena of arcing grounds. How does neutral grounding eliminate the arcing ground? Also enlist the advantages of neutral grounding. Nov-11 . Explain any one method of neutral grounding. May-13 May-13 (B) With help of circuit & phasor diagram explain resonant grounding method. Jun-12 Nov-11 Q 5 (A) Enlist the methods of neutral grounding. Draw diagrams to show voltage and current on the line before and after the wave reaches at the end. May-13 Discuss the behavior of a travelling wave when it reaches the end of (i) open circuited (ii) short circuited Q 5 (A) transmission line. Nov-11 . Jan-13 Discuss the phenomenon of wave reflection and wave refraction. Derive expression for refraction and Q 5 (A) reflection coefficients. May-13 Q 4 (A) Explain travelling waves of a transmission line when the receiving end is shortcircuited. show that surges behaves as travelling waves. Jun-12 Q 4 (A) Explain traveling and reflecting waves on transmission line with open end at the receiving . Find expression for (B) surge impedance and wave velocity. Jun-12 Starting from the first principles.PSAs : Questions from Ch-8 Transients in Power Systems Quastion asked in papers paper of (B) Explain single and double frequency transient.
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