Indian Railways is one of the biggest consumers of fossil fuel in the form of diesel. Thousands of
diesel locomotives that are in operation and diesel operated generators in LHB model trains consume lot
of diesel oil. However, of late various initiatives have been taken by NFR to cut down the use of fossil fuel
in line with the environment friendly policies of the Railway Ministry. This is expected not only to cut down
the train operation cost but also the precious foreign exchange of our country which is needed to import
fossil fuel apart from reducing air pollution.
“Auxiliary Power Unit” (APU) have already been fitted in 94 out of 399 diesel locomotives in NFR
for saving of diesel fuel consumption when the engine is kept in idle condition. Normally a diesel engine
consumes about 25 ltrs of diesel per hour during idling condition i.e. when the train is not moving. But with
the use of APU the idling consumption gets reduced by 1/10 to just 2.5 ltrs per hour. Thus huge quantity of
diesel oil can be saved.
APU is a self contained system with its own small diesel engine coupled to low capacity
compressor and alternator to maintain the main reservoir pressure, battery charging, operate HVAC
system in driver’s cabin and other small loads as per requirement. The main engine gets started only
when it is actually required for movement.
The central control system of the locomotive continuously monitors the battery status, engine
temperature, idling status etc. If the engine idling time is more than 10 minutes, the system automatically
shuts down the main engine and run the APU engine.
APU has a baby compressor, which produces compressed air and feed locomotive main reservoir
to compensate the formation leakages. When the APU engine is in operation, the system continuously
monitors the critical parameters and ensures that they are within limits. If any of the monitored parameters
are deviated from the limits, main engine starts automatically by stopping the APU engine.
It may also be mentioned here that few NFR trains have already started running by using HOG
technology where the diesel generators of LHB rakes are kept in shut down condition during their journey
in the electrified area to save fossil fuel.
