Reclosure occurs when power to a motor is briefly interrupted and restored before the magnetic field has fully collapsed in the motor’s winding. If this occurs while the applied power is out of phase with the collapsing field, significant damage can result. This session will address how this can happen and what measures can mitigate damage potential. It will include:

• Reclosing a switch or breaker before the magnetic field collapses
• Utilities’ automatic reclosure
• Contactor “chatter”
• Determining the time constraint
• Remedies: Time delay; Zero crossing