Thyristor Theory and Design Considerations

Thyristors can take many forms, but they have certain things in common. All of them are solid state switches which act as open circuits capable of withstanding the rated voltage until triggered. When they are triggered, thyristors become low−impedance current paths and remain in that condition until the current either stops or drops below a minimum value called the holding level. Once a thyristor has been triggered, the trigger current can be removed without turning off the device.