A bidirectional rectifier (essentially two SCRs in parallel) that function as an electrically controlled switch for ac loads and having an npnpn structure that can be triggered into either forward or reverse conduction by a pulse applied to its gate electrode. A triac will pass an alternating current. (Formal name is bidirectional triode thyristor.) A thyristor that can be triggered into conduction in either direction. Terminals are called "main terminal 1", and "gate".

Semiconductor switching element. Commonly used in a-c output modules for (PESs).

A solid-state switch which, when turned on, will conduct electrical current in either direction.