A TRIAC (Triode Alternating CurrentSwitch) is an electronic component that corresponds to a parallel connection of two thyristors, one of which is connected in the opposite direction. With such an arrangement, both half-waves of an alternating voltage
can be switched.
iacThe triac, which has two anodes and only one control electrode, provides the two required firing thyristor paths in the internal circuitry, allowing it to be switched to the low-resistance state by a current or voltage pulse for both half-waves of an AC
voltage.This state is maintained until the holding voltage of the anode is undershot and the triac switches back to the high-impedance state.
Triac circuits are used
, motor controls, and controls for alternating current. The current and voltage ratings for triacs are about 50 amps and several hundred volts, up to 800 volts.