Residual voltages analysis in reclosing process for induction machine

Induction motor required continuous running frequently comes with reclosing process due to interrupted supply in power frequency. However, large current and torque of the motor incidentally appear in the process. The paper firstly analyzes reclosing dynamic process of induction machine at the time of the absence supply and presence stator residual voltage. Then, the calculation model of stator residual voltage and rotor current at the period from absence supply to reclosing and stator current and motor torque after reclosing, has been established in three-phase stationary reference frame. In order to reduce impact current and torque at the reclosing instant, the paper analyzes the effect of phase difference of power supply and residual voltage on the current and torque, and presents a method of confirming optimal reclosing instant. By a simulating case, validity of the model and method has been verified, which provide a solid base for engineering application.