POWER SUPPLY SYSTEM USED IN INDIAN RAILWAY RAKES

There are mainly two types of the coaches called conventional ICF type and LHB is being manufactured at ICF,Perambur and RCF,Kapurthala .

There are three power supply systems as existing in Indian Railways to provide lighting, fan, air-conditioning and other needs of electricity for travelling passengers. 

These are :

Self Generating (S.G)

ALTERNATOR: -

     It is a source of electricity when the train is moving. For AC coaches two alternators of 25KW power each are used in a single coach. For general coaches an alternator of 4.5 KW power, per coach is used. V – Belts and Pulleys, connects the shaft of the alternator to axle.

2×25 kW alternators for AC coach and 1×4.5 kW for non-AC coach is mounted underslung, driven by a pulley-belt arrangement when driving pulley is mounted on coach axle. Output is rectified and charges 110V DC battery for continuous power supply to AC and non-AC coaches. AC load of roof mounted packaged units is supplied by converting DC into 2×25 kVA inverters. This system is followed over trains having a combination of AC and non-AC coaches.

End-on-Generation (EOG)

A EOG Generator Car at RCF

AC coaches draw power from the diesel-generating sets carried in coaches put in the front and rear of the rake, functioning at 415/750 V, 3 phase, 50 Hz AC supply. The power is distributed to entire rake and thus to each coach through two sets of 3 phase 415/750 V feeders. Each coach is provided with control, distribution and feeder changeover arrangement on 415/750 V control panel. The AC equipment  operate at 415 V, 3 phase, 50 Hz AC supply.

                             

Inside view of the  Diesel generator 

The air conditioning system in both types (SG or EOG) of Indian Railways stipulates use of open type compressor, condenser, liquid receiver with dehydrator separately mounted on the under frame of the coach. The evaporator comprising cooling coils, heater elements and blower fans with motor is mounted between coach roof and false ceiling. The conditioned air is blown through the central duct and distributed inside the coach through adjustable grills diffusers. 

Head-on-Generation (HOG)

his is the concept making round in Indian Railways since 1970’s. In this system, power is tapped from the locomotive and fed to the train through inter coach coupler. There are large many advantages with this system but still could not find enthusiasm among the designer and planners.  The load of 24 coach train (mix of SL and AC) is around 250kW and that of 21 coaches all AC train around 1000kW. For this 2x500kVA inverter to convert single phase into three phases is provided on Electric Locomotive and first such WAP5 locomotive is now working Shatabadi express between New Delhi and Kalka successfully since 2010. Similar efforts are also in progress for provisions in Diesel Locomotive since long.

HOG loco WAP-7

Power is supplied from the train locomotive at the head of the train. The single phase 25 kV transformer of the electric locomotive is provided with hotel load winding which is converted to three phase AC at 750 V using 2×500 kVA inverter and supplied to the same system as that of EOG. In case of Diesel Locomotive, three phase alternator is mounted on the traction alternator and feeds the hotel load. This is the most efficient system as the cost of power is about 25% less as compared to EOG, but the system is still under development for the last 30 years. The other class of trains namely Electrical Multiple Unit and Main Line Electrical Multiple Units employs the same system for coach lighting. The system is similar to what is followed in train-set composition of train having a power unit at head as well as on tail and power the entire load of the coach for comfort.