Thyristor products are also called a SCR (Silicon Controlled Rectifiers). A SCR Module is used to control and rectify current in only one direction. The SCR module works like a mechanical switch: it is either on or off. When a current/voltage pulse is applied to the gate of the SCR, it triggers on and starts to conduct. The SCR will continue to conduct even when the gate current is completely removed. The Silicon Controlled Rectifier will turn off once the load current drops below zero.