The photograph to the left shows a 150kW oil filled 3 phase 415 vac input/ 110 vdc 1250A output transformer rectifier unit that we recently repaired.

Due to incorrect connection of the firing board, one of the bridge thyristors had failed with an anode to cathode short circuit.

We de-tanked the transformer at the customers' works, changed the damaged thyristor in situ, reassembled, connected and re-commissioned the unit.