Thyristor Over Voltage Protection
Thyristor Over Voltage Protection
SCRs can be employed for protecting other equipment from over-voltages owing to their fast switching action. The SCR employed for protection is connected in parallel with the load. Whenever the voltage exceeds a specified limit, the gate of the SCR will get energized and trigger the SCR. A large current will be drawn from the supply mains and voltage across the load will be reduced. Two SCRs are used—one for the positive half-cycle and the other for negative half-cycle, as shown in figure. Resistor limits the short-circuit current when the SCRs are fired. Zener diode in series with resistors constitutes a voltage-sensing circuit.
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