V- I Characteristics
When the peak value of applied voltage is less than the break over voltage of triac and no signal is applied to the triac it will block both positive and negative half cycles of applied voltage. It can be turned on by applying positive and negative voltage to the gate terminal with respect to the terminal MT1.
Some applications of triac are light dimmers speed controls for electric fans and other electric motors and in the modern computerized control circuits of many household small and major appliances.
Triac can conduct in followings cases: