Power frequency alternating current over-current detection circuit suitable for dual-power change-over switch

The utility model provides a power frequency alternating current over-current detection circuit suitable for a dual power supply change-over switch, which comprises an input circuit, a protection circuit, a passive filtering and current limiting circuit, a voltage modulation circuit, a threshold comparison and output circuit, a first reference voltage source and a second reference voltage source, the other end is connected with a voltage modulation circuit through a passive filtering and current limiting circuit, and the voltage modulation circuit and a second reference voltage source are connected to a threshold comparison and output circuit. The power frequency alternating current over-current detection circuit suitable for the dual-power change-over switch is suitable for the dual-power change-over switch, and whether over-current occurs or not is judged by detecting the crest value or the trough value of the power frequency alternating current. And if overcurrent occurs, the overcurrent can be detected in