PHR1 series motor soft starter adopts intelligent digital control to carry out automatic control on the motor by using mono chip computer as the intelligent center and the controllable silicon module as the executing component. It is to be applied to squirrel cage as synchronous motor control with various loads, and helps the motor to start smoothly under any operation condition so that it protects the drag system, reduces the impact on the power network imposed by the starting current and ensures the reliable starting of the motor.