The over-voltage protection circuit (1)

Published:2011/6/14 2:42:00 Author:Christina | Keyword: Over-voltage, protection | From:SeekIC

The over-voltage protection circuit is as shown in the figure. This circuit uses the photoelectric coupler's on-off to control the device. When the voltage is normal, the photoelectric coupler has no output, the VT tube cuts off because of the reverse bias. When some reasons increase the voltage of this circuit, the voltage of the sampling circuit subprime stage will increase too, the photoelectric coupler meets the working condition. The light-coupler output current increases the VT tube's bias voltage and make the VT tube to conduct, the actuator's relay closes and cuts off the power supply to protect the electrical equipment. If the fault is eliminated, the voltage will be normal, this circuit will immediately quit the working condition to recover the power supply of the circuit.



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