Delta connection motor phase failure protection circuit

The protection function of this protection circuit is as follows: connect three resistors R1 to R3 to form an artificial neutral point. When the motor loses phase, the neutral point shifts, the relay KA is powered on, and the normally closed contact of the relay The contactor KM coil circuit is cut off at one point, KM is released when power is lost, the main circuit circuit of the motor is cut off, and the motor M stops.