"Operational and Technical Overview of Electric Locomotives at the Kanpur Electric Loco Shed"

"My Summer Report" provides a detailed account of the Indian Railways and the operations of electric locomotives at the Electric Loco Shed in Kanpur. It includes information on the history of Indian Railways, the establishment and functioning of the Electric Loco Shed, and technical descriptions of the components and operations of three-phase locomotives. The report discusses various parts of the locomotives such as the pantograph, servo motor, lightening arrester, circuit breaker, main transformer, harmonic filter, traction motor, battery, cooling fan, and compressor. It also explains the working of traction converters and provides circuit diagrams for different locomotive models.

1. Presentation On Electric Loco Shed, Kanpur By: Owais Ali(2200430200042 ) Submitted To: Mr . Sahitya Kumar Electric Loco Shed, Kanpur North Central Railway

2. Introduction to Indian Railways Indian Railways is a major transport system operating on tracks, providing an economical means of commuting and transporting goods over various distances. It boasts the fourth largest railway network globally, with a route length of 68,043 km, a running track length of 102,831 km, and a total track length of 128,305 km, 58,812 km of which are electrified as of March 2022. Established in 1951, it is divided into 18 zones and 70 divisions. The first railway proposal in India was made in 1832, and the first passenger train ran from Mumbai to Thane on April 16, 1853, covering 34 km.

3. Introduction To Electric Loco Shed, Kanpur Electric Loco Shed, Kanpur, established in 1965, is a key facility for maintaining and repairing electric locomotives for Indian Railways, located in Kanpur, Uttar Pradesh, under the North Central Railway Zone. With a sanctioned capacity of 150 engines, it currently houses 306 units, including 78 WAP-7 and 228 WAG-9 locomotives. The shed performs regular maintenance, overhauls, repairs, painting, and washing of locomotives. Known for its historic significance and innovative maintenance practices, it supports trains primarily traveling north and east, serving as a model for other sheds. The dedicated team of administrative officers, supervisors, and staff ensures efficient operations.

4. OPERATION OF 3 PHASE LOCOMOTIVE The locomotives uses three-phase squirrel cage rotor type induction motors. Because of high starting torque, good efficiency and easy to speed control lacking of brushes and commutators, so they requires less maintenance. Pantograph receives 25 KV single phase AC supply from over head electric line (OHE) and this AC voltage passes through vacuum circuit breaker (VCB) mounted on the roof of loco, then it goes to the primary of the auto transformer fitted under the locomotive to stepped down the voltage. The output voltage from secondary of the transformer goes to the Traction converter. The main function of traction converter is to convert fixed 1 phase AC voltage into variable 3 phase AC voltage.

5. There are 2 types of traction converter (IGBT and GTO based) Generally we used IGBT based traction converter in 3 phase locomotive. Traction converter supplies the variable three AC voltage (max 2180 volt) and frequency (from 65 to 132 Hz) to run each 3 phase induction motor One traction converter can drive only 3 induction motors, in one locomotive (WAP 7/ WAG 9) has two sets of bogie (co-co) and each bogie has three motors So there are six induction motors in one locomotive. One traction converter can run only three motors, so there are two SRs (SR-1 & 2) are used to run six motors. Motors starts to rotate and it is directly connected to the wheel with the help of gears, so the locomotive will start to move. Figure 3 : Three phase induction motor based locomotive

6. PARTS OF LOCOMOTIVE Pantograph It is pneumatically Operated equipment mounted on the roof for collection of current from overhead wire (OHE). Pantograph is operated by an electrically controlled servo motor. Pantograph

7. Servo Motor It is an electric motor fitted on the top of the locomotive which is used to control (lift up/down) the pantograph. Sarvo Motor is Special Machine that operate with the help of servo mechanism which is used to complete a specific task in precise way. There are two types of servo motors Ac servo motor DC servo motor Servo Motor

8. Lightening arrestor and insulators It is a device mounted on the roof of electric locomotive which is used to protect the train from the lightening. Electric lightening is very dangerous when it falls on the train, lightening arrester comes into the picture and do easily grounded through the wheels. Insulators provides the insulation between electric conductor and body of the electric locomotive. Lightening arrester and insulators

9. Circuit breaker An electric loco is almost always provided with some sort of circuit breaker to isolate the power supply when there is a fault occur or for maintenance. There are two types the air blast circuit breaker and the vacuum circuit breaker VCB. Vacuum circuit breaker

10. Main transformer It is an autotransformer which is utilized for drawing various grades of voltage required for operation of locomotive. An auto transformer is a one winding transformer in which a part of the winding is common to both primary and secondary windings an auto transformer has a single continuous winding with a tap point between primary and secondary winding. The tap point can be adjusted to obtain the desired output voltage, hence this is an obvious advantage of the autotransformer. The main disadvantage of the autotransformer is that the secondary winding is not electrically isolated from the primary. Transformer

11. Advantages of autotransformer An autotransformer has a smaller core and copper losses and hence higher efficiency as compared to an ordinary two winding transformer. It has better voltage regulation due to reduced voltage drop in resistance and leakage reactance. It has a smaller size and cheaper than 2 winding transformer. It requires smaller excitation current. An auto transformer can produce variable output voltage. Disadvantages of auto transformer An autotransformer has reduced internal impedance as compared to a 2 winding transformer which results in a larger short circuit.

12. Harmonic filter The Harmonic Filter reduces the high frequency harmonics to avoid disturbance in signaling. If the harmonic filter gets by-passed by the system, the speed of the locomotive will be automatically restricted upto max. The complete Resistor Assembly is mounted on the roof of the Locomotive. Harmonic filter

13. Traction motor 3-phase squirrel cage rotor type induction motor is used as traction motor in locomotive. It is one of the most important equipment in the locomotive which transmit power to the wheels for moving the trains. A 3-phase induction motor is an electromechanical energy conversion device which converts 3-phase input electrical power into output mechanical power. A 3-phase induction motor consists of a stator and a rotor. The stator carries a 3-phase stator winding while the rotor carries a short-circuited winding called rotor winding. The stator winding is supplied from a 3phase supply. The rotor winding drives its voltage and power from the stator winding through electromagnetic induction and hence the name. 3-Phase induction motor 3-Phase Stator winding

14. Parameters Cont. Max Power 850 KW 850 KW Speed 1283 RPM 2584 RPM Voltage 2180 V 2180 V Current 270 A 383 A Frequency 65 Hz 132 Hz Cooling Air ---- 810 m 3 /min Motor Ratings (as shown ) Synchronous speed, Ns = 120f/P Rotor Speed Nr = (1-s)Ns Where, s =slip = (Ns- Nr )/Ns Squirrel cage rotor

15. . Battery All trains are provided with battery to provide a startup current and for supplying the essential circuit such as emergency lightning when the line supply fails. The battery is usually connected across the DC control supply circuit and it helps to lift up the pantograph at starting of locomotive. Some companies are making battery for Indian Railways like Kirloskar Exide Celtek Microtek

16. Traction converter A traction converter in a three-phase locomotive converts 25kV single-phase AC to three-phase AC with variable voltage (up to 2180V) and frequency (65 to 132 Hz). Each locomotive has two converters (SR-1 and SR-2), powering different sets of traction motors. For WAP-5 locomotives, SR-1 powers motors 1-2, and SR-2 powers motors 3-4. During electrical braking, traction motors act as generators, sending three-phase AC to the traction converter, which then converts it back to single-phase AC and feeds it to the main transformer. This supply is then stepped up and fed back to the overhead electric line (OHE), making the loco a small powerhouse.

17. The traction converter consists of three main parts: Line Converter (NSR ): Converts AC from the main transformer to DC for the intermediate DC link, and vice versa during braking . 2. Intermediate DC Link: Smooths the DC and stores energy, acting as an electrical buffer . 3. Drive Converter (ASR ): Converts DC from the intermediate link to three-phase AC for the motors and converts AC to DC during braking. The assembly of these parts forms the traction converter.

18. Technical Data of Traction Converter Input voltage (RMS) 2 × 1269 Volts Input voltage (RMS) 2 × 1142 Amp Coolant oil SHELL DIALA Input frequency 50 Hz DC link circuit nominal voltage 2800 Volts Output voltage (line-line voltage, RMS) 2180 Volts Output current (per phase, RMS) 740 Amp Output power 2105 KW Output frequency 65-132 Hz

19. Machine room layout

20. GTO-Based Traction Converter A Gate Turn-Off (GTO) Thyristor is a 4-layer, 3-terminal device (anode, cathode, gate) used in traction converters. It acts like a combination of PNP and NPN transistors and is current-controlled, bidirectional, and optimized for low conduction losses. Typical switching frequencies range from 200 to 500 Hz, with transition times of 10-30 microseconds. In 1993, Indian Railways procured 3-phase AC electric locomotives with GTO-based drive systems from ABB, Switzerland. These systems include GTO-based traction converters, auxiliary converters, and MICAS-based Vehicle Control Units (VCU). GTO requires only a pulse for switching, unlike IGBT, which needs continuous gate voltage. Specifications: 1. Oil cooled 2. Two drive valve sets 3. Two line valves 4. Converter control system "MICAS" GTO based traction converter

21.   IGBT BASED TRACTION CONVERTER IGBTs are state-of-the-art power electronics used in the traction systems of electric rail vehicles, offering reduced current requirements, minimized heat, and traction noise, while enhancing acceleration efficiency . Functionality: Traction inverters drive or brake one or multiple traction motors using DSP for Vector motor control with Space Vector PWM, ensuring complete VVVF control in motoring and dynamic/regenerative braking operations. The input power comes from a stable DC Link voltage, with torque commands from the locomotive control system. Independent motor control in locomotives provides better wheel slip control, tractive effort independent of wheel diameter variations, and improved power availability during inverter or motor failures. Medha uses IGBT devices in all traction inverters for enhanced efficiency and reliability

22. Gate drive cards control IGBTs and offer short circuit protection, with optic fiber communication between traction computers (DSPs) and gate drive cards for noise immunity. Sensors monitor current, voltage, and temperature for inverter and motor protection. Working: Traction converters feature multiple line converters that convert single-phase AC input to a stable DC link bus voltage. One or more inverters then convert this DC voltage to three-phase power to control the traction motors. IGBT Traction Converter

23. WORKING OF IGBT TRACTION CONVERTER Traction Converter would have multiple line converters which convert single phase AC input to a stable DC link bus voltage. A combination of one or more inverters converts this DC bus voltage to 3-phase power controlling one or more traction motors each. Block diagram of traction converter

24. POWER CIRCUIT OF 3 PHASE LOCO Circuit diagram of 3-phase locomotive (WAG 9)

25. Traction power circuit

26. Comparison between GTO and IGBT GTO IGBT GTO stands for Gate Turn Off Thyristor IGBT stands for insulated gate bipolar transistor GTO has 3 PN Junction IGBT has only one PN junction GTO has three terminal anode cathode and gate IGBT has three terminal emitter collector and gate GTO is a current controlled device IGBT is a voltage controlled device It has more no. of electronic cards (16 cards) so its efficiency is less It has less number of electronic cards (7 cards) so its efficiency is too much high It has more harmonic effect It had less harmonic effect GTO has larger in size and its weight is more as compare to IGBT IGBT is smaller in size and its weight is also less Comparison between GTO and IGBT

27. Thank you