Main transformer: This steps down the 3Φ 415V supply to the require value of voltage.
Synchronizing transformer for phase sequence: This gives the synchronizing signal to the ** card. That is, the pulses from this card if fed to the ** card. The ** card gives pulses to the SCR of R or Y or B depending upon which phase is positive maximum.
Half control module: This has a diode and a SCR for each phase. The ** card controls the ** angle of SCR.
Firing card: This gives the ** pulses to SCR depending on phase sequence and the feed back from output.
Controller card: This card monitors the output and gives signal to ** card to conduct at certain angle to maintain constant output voltage.
Power supply card: This gives power supply for the controller card, ** card and protection.
