This is Magnetic Amplifier Type having Two  Magnetic Amplifiers to control the field current. The out put Voltage can be set from 125 to 130 Volts DC and the current can be set from 180  to 212 Amps. as per the requirements of Railway. Over Current Protection is inbuilt 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 to avoid the Over Voltage Generation which will be harmful for the coach appliances and maintain fail safe operation.