Indian Railways decided to install a new fuel saving device called Auxiliary Power Unit (APU) in Diesel Locomotives which will result in saving of more than 20 lakh Rupees per locomotive annually.
As a start up, the APU has been installed in twelve existing diesel locomotives through retrofitment. It was planned to fit APU on 100 per cent in newly built diesel locomotives which will then result in saving of more than 60 crore Rupees annually in the future. It is important to note that the use of APU also results in lower carbon dioxide emission and other pollutants like HC, NOx and CO.
Purpose of installing Auxiliary Power Unit (APU)
Due to a large number of trains, moving on limited track, some trains have to wait for path or for giving precedence to other trains. Locomotives of these trains remain in idle condition because of the requirement to provide compressed air for train brake which is supplied by compressor driven by engine and to charge the locomotive battery. In order to save fuel during idling, Indian railways are providing a system called Auxiliary Power Unit (APU) in Diesel Locomotives.
In APU System main Engine shuts down and small 25 HP Engine starts, and charges batteries and air brake pipes, when locomotive idles for more than 10 minutes. The diesel engine of APU consumes only three litres of diesel per hour in comparison to 25 litres by the main engine. The expected savings per locomotive fitted with APU will be 20 lakh Rupees annually on account of saving in fuel oil only.
What is Auxiliary Power Unit (APU)?
APU is a self-contained unit containing a small diesel engine coupled to a compressor and alternator for battery charging. It has its own set of controls, accessories and is integrated to the existing microprocessor control system of locomotive.