This is Electronic Control having two numbers IGBTs to control the field current of the 4.5 KW Alternator. The output Voltage can be set from 120 to 130 Volts DC insteps of 0.5 Volts and the current can be set from 38 Amps to 45  Amps. as per the requirements of Railway. Over Current Protection is in built in the Regulator in case the output current exceeds the rated current and protect the devices.  An OVP (Over Voltage Protection) with electronic Control is used in the Control box to open the field control in case the control fails or the control components damage to avoid the Over Voltage Generation which will be harmful for the coach appliances and maintain fail safe operation. A display board is provided in the control panel to set the voltage and current.

The complete data of the ERRU for one week operations is stored in the data storing device and can be downloaded to study the behaviour of the alternator and the ERRU. There is fault detection provision in the display board and also in the storing facilities which can be monitored from the down loaded data and the corrective action can be taken.

An  emergency circuit is provided to control the output in case of the control failure in ERRU.