Abstract: Nowadays, relay protection device are widely used in electricity distribution line, playing an important role in the healthy operation of electricity distribution line. When maintaining the line, it is often necessary to switch on and off the relaying plate of the protection device. If the relaying plate is not restored in time after temporary switching on or off, it will affect the action of the protection device, and the electricity line will not be able to detect the fault in the power system. The outlet pressure plate circuit is connected with the opening and closing coil of the circuit breaker. If the method of detecting the pressure plate on and off by voltage and current is used, it will inevitably trigger the opening and closing coil mode, which will inevitably cause the circuit breaker to malfunction. This article introduces and compares several methods for monitoring the relaying plate, and analyzes the applicable scenarios of various methods, This method is suitable for transforming the automation terminal equipment that has been put into operation on site.