Phaseloose protector for motor

The utility model provides a phase-failure protector for a motor. Three symmetrical capacitors are respectively connected with three-phase wires according to star connection, a star point is connected with a relay coil after rectified by a diode, and the normally closed contacts of the relay are connected with a control loop of a main contactor. When any phase failure of a three-phase power cord is opposite, star point voltage displaces, the relay can operate after the star point voltage is rectified by the diode, the contactor has power cut, and the motor can not operate any longer when the normally closed contacts D and E are disconnected. The utility model has the advantages of simple circuit, few elements, low cost and high reliability.