Overvoltage surge inhibition circuit

The utility model discloses an overvoltage surge inhibition circuit, and the circuit is disposed between an external power supply and electric equipment. The circuit is connected with the external power supply through a power input end comprising a power positive input end and a power negative input end, and is connected with the electric equipment through a power output end comprising a power positive output end and a power negative output end. The circuit comprises an active clamping circuit and an isolation drive circuit, which are connected with each other. An external low-voltage control signal is loaded to the input end of the isolation drive circuit, and the output end of the isolation drive circuit is connected with the control end of the active clamping circuit. The input end of the active clamping circuit is connected with the input end of the external power supply, and the output end of the active clamping circuit is connected with the power output end. The external low-voltage control signal is generated by an external preset signal generation device, wherein the power output end supplies power to the external preset signal generation device. The circuit can effectively inhibit the overvoltage surge, and meets the requirements of electric equipment of high speed railway and rail transit on power.