At three-phase AC motor in has made under-voltage, open-phase protection and irreversible transmission device for phase sequence protection, with reliable performance, wide application and easy to use and so on. The family protector according to Fig access the power control loop, which can play a protective effect, three-phase circuits of any one fuse or open circuit Open-phase power supply line when there is immediate action CW-3 control to cut off the main circuit contactor AC contactor coil power supply, so as to achieve the main contactor AC contactor moves off of the motor phase protection. When irreversible three-phase equipment (such as pumps, fans, air compressors, elevators, electrical, etc.) that the phase sequence at after repair or alteration of power lines and the original phase sequence that mistake next time, CW-3 series with same ability to discern Preface reliable job, and stop on the circuit power supply to achieve the purpose of protective equipment.