What devices are required to give adequate protection to the motor?

  • Under-voltage release to prevent automatic restarting after a stoppage due to a drop in voltage or failure of the supply, where unexpected restarting of the motor might cause injury to an operator.
  • Overload relays for protection against excessive current in the motor windings - e.g. in the event of overload or failure of the motor.
  • Earth fault.
  • Single phase protection.