Working Of SCR On ac

An SCR comes on when a forward current passes from the gate to the cathode. Once switched on it remains on so long as the minimum holding current passes from the anode to the cathode. When the reverse voltage is applied it behaves like a reverse biased diode.
Unless the gate is forward biased, the SCR will not trigger. If an AC is applied. The scr will trigger on positive half cycle. If the AC is also applied to the anode and cathode, the SCR comes on during positive half cycles.
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