The most common type of power supply used for impressed current cathodic protection is a transformer/rectifier, commonly referred to simply as a rectifier. A rectifier converts the AC power supply voltage to the required output voltage and then converts it to DC. Rectifiers are either supplied in ventilated cases to allow convective air cooling or are immersed in transformer oil. Rectifiers are normally powered by an AC power system. The rectifier input is an
AC voltage from the commercial electrical power grid or an engine-generator. A transformer with tap adjustments in the secondary side provides a method to reduce and adjust the output voltage level and to isolate the DC circuit from the input power system. A rectifying circuit next converts the adjusted AC voltage to produce a DC voltage output. It can be supplied as air cooled & oil cooled, single phase & three phase.