Typically, each rectifier unit consists of 2nos. main rectifier cubicles with high current silicon diodes mounted on DM water-cooled aluminum heat sinks connected to an incoming HT AC line via a regulating transformer with OLTC along with one or two rectifier transformer having configuration of double star with IPT or 3 Phase bridge connection. The control cubicles are equipped with state-of-art PLC based control to achieve the required time based constant power regulation, parallel operation of the two rectifiers with equal load sharing, semiconductor fuse failure monitoring, OLTC raise/lower operation, alarm annunciation, etc.

The voltage range required for starting and controlling the output of the process is obtained with the help of transductor in conjunction with the on-load tap changer mounted on regulating transformer.

The large current rating of rectifier equipment is achieved by high power semiconductor diodes connected in parallel on a common heat sink for each phase. The heat sinks are either forced air cooled or forced de-mineralized water cooled depending upon rating and application.

The forced air cooled designed have been basically developed for large voltage and large current application where water cooling cannot be adopted due to restriction of DM water property.