AC phase sequence affirmation and phase loss protector

The utility model provides an industrial-frequency three-phase AC phase sequence affirmation and phase losing protection device, which is composed of a step-down circuit, a DC working power supply, a sampling circuit, an SCM, a display circuit and a control circuit, wherein, the sampling circuit is composed of a step-down resistor and a photoelectric coupler; the control circuit is composed of an affirmation key and electromagnetic relays; the device eliminates an electro-magnetism transformer, adopts an SCM to further simplify the circuit, and has the characteristics of flexible and diversified functions. The device is used to protect an irreversible apparatus or apparatus which can not operate under phase-losing, and has advantages of simple structure, small size and wide range of application.