Silicon Controlled Rectifier (SCR) of an Static Generator Exciter
This is one of the six Silicon Controller Rectifier (SCR) of the static excitation system of a 60 MW electric generator. The six SCR’s formed a bridge that converts the AC to DC voltage. SCR is used instead of bridge diodes to convert AC to DC because of its capability for its voltage output to be controlled electronically by just changing the triggering angle. However, unlike bridged diode which could have a steady DC output, the outage voltage of the SCR based excitation system is pulsating. But it doest matter if used as an exciter voltage for the electric machine.
Observe the massive heat sink of the SCR. This is required to dissipate the heat loss due to the huge magnitude of current that passes in the devise.
Posted in Electrical Machines