This is Magnetic Amplifier Type having one Magnetic Amplifier to control the field current. An excitation transformer is used to match the voltage for the Magnetic Amplifier Control. The out put Voltage can be set from 120 to 130 Volts DC and the current can be set from 35 to 40 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.