INDUSTRIAL VISIT REPORT1 THE KERALA ELECTRICAL AND ALLIED ENGINEERING CO. LTD Dept.of.EEE YCET With a manpower base of 1500. More than 25. The product has been developed through the company’s own R&D efforts. It has fully mechanized moldings lines with sophisticated testing equipment to ensure quality casting. The company has four manufacturing units loaded in various districts of the state.000alternators are in service with the Indian railway alone.of.INDUSTRIAL VISIT REPORT 2 INTRODUCTION The Kerala Electrical and Allied Engineering Co. Statodyne Alternator Division Manufactures stat dyne brushless alternator The alternator is used for lighting and air-conditioning of Railway coaches. Dept. they have gradually broadened our manufacturing base strategically to reach domestic and overseas market. Charging system division Manufactures brushless alternators for automobile charging system. KUNDARA UNIT. India and is fully owned by the state govt: As a company engaged in multi various activities. Foundary Division Manufactures Spherical Graphite iron and Grey iron Castings. popularly known as KEL was established in 1964 in the state of Kerala. KOLLAM DISTRICT INCEPTION: 1964 1. 2.EEE YCET . they are one of the biggest public sector companies in the state. The alternator caters to the high power needs of modem vehicles and heavy earth moving equipment. The foundry has capacity of 1500 MT per annum. It offers long Ve and maintenance free operation. Ltd. which includes more than 250 highly qualified and well trained professional engineers. 3. of.INDUSTRIAL VISIT REPORT 3 Dept.EEE YCET . Before doing any test the surface should be made smooth by grinding and finishing. The type cut depends on the thickness of the plate. to be seen more clearly.penetrate test The purpose conducting these tests is to check for cavities and cracks. usually using a double V joint. A suspension pin =. Some of the tests conducted are .EEE YCET . Die. at first a cleaner is sprayed and the surface is cleaned with cotton.of. The body is not cast because it increases the brittleness.INDUSTRIAL VISIT REPORT 4 FABRICATION FABRICATION OF STATOR FRAME The alternator stator frame is made of mild steel. After the test is conducted. Radiography . is also provided so as to support the alternator. after which a driller is used to punch it. the sheet is subjected to prebending in hydraulic press. Then a color is sprayed to see the cracks clearly. which is the hanging unit. To get perfect circle. Fines are provided on the outer frame to facilitate air-cooling. before rolling. in the Die penetrate test. It is cut using a gas cutter. Different tests for checking the quality are then conducted. After this a developer is used to make the cracks. They are dimensioned. Dept.Ray test . It is constructed by basically rolling steel sheets. due to which the input to the machine changes. the various accessories like the tension lag and lead box are provided the frame. if any. cut and welded. The plate sizes are according to requirement . There is a regulator rectifier unit by means of which the output of the machines kept constant always even if the speed of the train varies. X . For example. the stator diameter is fixed. which is corrected to 255 mm only 52 micron variation is permitted. the inner diameter corrected to accommodate the windings. After this. The unite obtained from fabrication is of 249 mm diameter. Consider a 25 KW alternator.of. Thus the following processes are carried out on the stator frame: Boring Drilling Slotting Stacking of Laminations Filling The stator frame is now passed on to the winding section Dept. This is then compressed under a pressure of 6 kg/cm to press it. Here silicon steel laminations are stacked on one another as shown in diagram. Fiber laminations are fixed on to the circular clips to prevent loss of insulation. A guiding ring is used to prevent twisting.INDUSTRIAL VISIT REPORT 5 MACHINE SHOP The section deals with the following production processes: 1) Insertion of stator stampings in to fabricated outer frame 2) Assembly of rotor 3) Fabrication of pulleys These processes are explained in detail STATOR FRAME Based on the shelf number. it goes to stacking and pressing equipment.EEE YCET . of.5 m length of wire shall be taken from the reel 1) Two pieces of 250 mm long wire shall be the cut from both ends. The difference between the overall diameter and the base Dept. The enamel shall be from a length of 60 mm of wire by exposing it to flame till it come red-hot. Then dip is in ethanol.40 1. The wire shall be cleaned using a piece of cotton. of revolutions b) DIMENSIONAL CHECK 1.18 1.INDUSTRIAL VISIT REPORT 6 TESTING OF COMPONENT 1.5 2. The later is loaded according to the table to apply tension to the rotating wire. The average of 6 measurements shall be reported as over all diameters. but can displace axially.EEE YCET .5 4 93 88 78 68 Load No. Nominal diameter of the conductor 1. The diameter of the bare copper wire shall be measured as above the and their average is the bare copper diameter.60 2. TESTING OF COPPER WIRE A) PEEL TEST A specimen of wire about 600 mm length shall be placed in a key the apparatus consisting of two fixing devices 500 mm apart in the same axis. One of there is able to rotate and other cannot rotate.85 2. 2) The diameter of enameled conductor shall be measured using a micro meter at three position are 1200 angular displacement around the circumference of wire.25 1. 071 Max overall Base Max Cu dia Min Insulator Thickness Max diameter(mm) c) SPRINGNES TEST METHOD OF TEST: A sample of about in shall be wound 5 times around the manned with a diameter as given the table three.412 0.063 0.00 1.067 0.891 0.349 1.010 1. So that the spring aback for one turn is read directly in degree.606 0.990 1. This end of the Dept.25 1. TEST APPARATUS: the general arrangements of the apparatus is shown figure.909 1.094 1.279 1. The specified weight is attached to one end of the sample of wire and after unlatching the meandered so that it will rotate freely the other and of the wire is inserted through the transfers hole in the mandrill at the commencement of the helical grove so that sufficient wire project on the other side of the mandrill.502 1.485 0. Nominal conductor Diameter (mm) 0.515 0.263 1.422 0.EEE YCET . The dial is marked with 72 equally spaced divisions.INDUSTRIAL VISIT REPORT 7 Conductor diameter shall be found and the overall diameter conductor and increasing diameter shall be according to able.50 0.414 1.192 1.989 1.18 1.417 0.069 0.40 1.060 0.067 0.9 1.022 0. The apparatus shall be maintained twit the shaft of the mandrill horizontal. The specified mandrill shall be locked in position so that the hole form fastening the wire and the commencement of a the helical grove is a vertical position to correspond with zero on the dial and shall then be dusted with finally powdered talc to avoid danger of the annealed wire dinging to the surface of the mended.386 1.168 1.466 0.of.2370 1. 57 4.12 1.31 8.01 The tested components are passed on to winding section Nominal dia of the conductor 0.90 0.00 1. The tolerance on the measured core loss shale is 0. 2) TESTING OF LAMINATION a) CORE LOSS MEASURMENT The core loss shall be measured using lamination tester the value shall be as given below.53 1.8 1. The mandrill is thus aligned with the dial zero vertically downwards.25 Mandrel dia(mm) Tension (kg) Spring back(max) 25 50 50 50 50 50 50 0.53 1.INDUSTRIAL VISIT REPORT 8 wire is hold firmly and the weight is carefully lowed to apply tension the sample.53 44 48 46 45 41 39 37 Dept.53 1.5 watts.53 1. Material Grade CRNGO M-36 M-43 M-45 M-47 Core loss 3.EEE YCET .18 1.of.53 1.01 5.417 0.95 1. A winding catcher or pole shoe.EEE YCET . The core of the stator which is completely embraced by the field coils will retina a residual magnetism is excited by a battery once. uniformly distributed on the rotor surface skewing the rotor axis.INDUSTRIAL VISIT REPORT 9 WINDING The KEL brushless alternator does not have a rotor winding. Both accommodated in the stator. The stator has 36 slots divided symmetrically in to two about the horizontal axis two diametrically gaps each equal to 6 slots called cut in space. The difference with the conventional alternator lies in the method in which this alternating flux is produced. Rotor consisting of stacked stamping resembles a cogged wheel having eights seat of teeth and slots. The slots are insulated using imported Nomex paper. The emf is produced by change in flux. Each field span half the total number of stator slots AC coils are connected in star and field coils connected in series. This is to support the field coils. the flux produced by the field coils finds its path through the rotor when the rotor is rotated the passenger of rotor teeth and slots alternatively under the fields offers a varying reluctance path for the flux produced by the field coils. However the basic principal of alternator does not change. Aluminum is used because no magnetisms should be produced with the catcher. CONSTRUCTION AC winding is accommodated is in the slots in the stator. is used for supporting the field coils. are proved on either side of the stator frame. It has very high dielectric strength. The alternator consisting of two winding. The core of testator is completely embraced by the field coils. Dept. made of aluminum. The AC winding is distributed in the small slots and field windings are concentrated in to slots. Normally AC winding and field winding.of. of.5. inside which a vacuum is created. Capacity 25KW Class H Preheating 4-5Hrs at120 degree Cooling Till temp reaches 50 degree 4.12. The remaining varnish is return to the tank. Then the varnish is admitted and pressure is applied.INDUSTRIAL VISIT REPORT 10 VARNISHING This is a trivial section of the manufacturing process. The chart below gives the criteria for varnishing different alternator.18 KW F 4 hrs at 1200130 degree Till Temp reaches 50 degree 4-6 Hers at 140 Curing 8-10 Hrs at 120 degree Flowchart for varnishing Mixing Checking of viscosity of varnish Transfer of heated frames to vacuum Apply pressure (curing) Return to varnish Cooling Dept. Here at first the varnish is mixed. and then its viscosity is checked after that preheated stator frames are transferred to a chamber.EEE YCET . The stator frame when the winding shop is given to the varnishing section. Control circuit is wired in rack consisting of the following parts. The voltage regulator monitors voltage and pass a command.the three phase ac output of ac alternator is rectified by these diodes to obtain dc output. POWER RECTIFIER This consist of 6 numbers of silicon diodes connected in three phase full wave bridge .EEE YCET . Regulating output current at set value. Transformer has 5 sets of terminal brought required to a terminals strip. 3.of. 2. this control circuit to reduce excitation current as soon as the output voltage reaches the set value.INDUSTRIAL VISIT REPORT 11 REGULATOR RECTIFIER UNIT The regulator rectifier unit has mainly the following functions. The absence of voltage regulator. VOLTAGE REGULEATION VOLTAGE induced in ac windings of alternator depends on the speed of the rotor excitation current and load current. Dept. output voltage is rising the indefinitely due to the positive feedback of the field. EXCITATION TRANSFORMER This is a single winding transformer with tapping for input and output transformer stepped down the voltage for field coils. Rectifying 3 phase output of alternator to dc using full wave Rectifier Bridge. Each diode is protected against transit surge voltage by capacitor C1. Regulating the voltage generated by alternator at the set value. 1. Whole bridged is protected Against high frequency surges by capacitor C3 and DC output is filtered by capacitor C2. It works on the principle of saturation of magnetic core. maintaining the output voltage of the alternator of the set value. It has 6 sets of winding. it consist of in network of zenor diode potential dividers and rheostat .of.these diodes conduct alternatively as terminals 18 and 161 becomes positive with respect to the center taping -19. Dept. MAGNETIC AMPLIFIER Magnetic amplifier forms of the nuclease of the evaluated circuit.EEE YCET . in the output voltage of the load winding aw here by decreasing the field current. The load winding is connected in the field circuit & the field current passes through this winding subject from the command from the voltage and current sensing ckts. The load winding offers variable impedance to the field circuit there by regulating the voltage and current at set value. FIELD RECTIFIER UNIT Silicon diodes dD2 and D3 acts as full wave rectifier for the field supply . The voltage drop across R1 can be varied by varying the resistance Rh.manifested through control windings 10-11 and 26-27 respectively. The rectified current from the diodes is taken to the field back winding 20-40 of the magnetic amplifier to terminals 20 and 19 the positive and negative terminal respectively for the field supply.INDUSTRIAL VISIT REPORT 12 2) VOLTAGE DETECTOR Voltage detector serves the functions of providing necessary error signal for voltage regulation. The rotor is rotated at low speed inside the stator and checked for contact. The bearings are sent for greasing. Either roller bearing or ball bearing is provided. o Rotor and axle pulley (machine shop) o Stator with laminations and winding (varnishing) o Regulator unit The assembly can be briefly explained as follows.of. Here all the components are assemble3d together and readied for dispatch. this is the final section in terms of the alternator manufacture. The symmetry of air gap is checked by mechanical means.INDUSTRIAL VISIT REPORT 13 Final Assembly As the name suggests. It is assembled on site by mounting. The end of the rotor shaft is padded through the end shield. The rotor shaft is cleaned and polouished. All components are cleaned and scrapped to remove superfluous metal The bearings are fitted. Dept.EEE YCET . This receives the following from the preceding areas. The alternator pulley is mounted on to the rotor shaft. along with bearing lock. The end plate is fatted after heating on the bearing side. The axle is sent as two separate pieces. High Voltage Test This test is performed to find the leakage current. They are briefly explained below. Mechanical Over speed Test. The maximum limit is 20 mA. The field is separately excited and is run at a high speed in both the directions. For this all the current carrying parts are shorted and earthed. This test can be used to check whether the machine has the capacity to withstand such a high voltage. The induced emf in all three phases in both the directions is noted. The speed range is as given below 4. The value should be within the specified range. The minimum value of insulation resistance is 20 MC2. The leakage current can be directly read using a milli ammeter. Dept.EEE YCET .75 kW 3275rpm 3035rpm 3035rpm. A supply of 1500V is given to the stator plate. This test is done both before and after the high voltage tests. The current carrying parts are shorted and connected to one of the terminals of the meager.of.5 kW 18 kW 22. Insulation Test Insulation meager is used to perform this test. The other terminal is given to the stator frame. The resistance value can be directly reads.INDUSTRIAL VISIT REPORT 14 Testing The assembled alternator is subjected to various tests as per RDSO specification before dispatch. Ernakulum District. It is an ISO 9001-2000 Certified Company.INDUSTRIAL VISIT REPORT 15 CONCLUSION Kerala Electrical and Allied Engineering CO. Dept. They are located in Mamala.of. Olavakod. It has three other units in addition to Kundara unit.EEE YCET . Ltd is a Kerala Government owned company. Palakkad District and Kasargod District. EEE YCET .INDUSTRIAL VISIT REPORT 16 Dept.of.