Overload Relays

An overload relay is a device that protects an electric motor from overload and phase failure. It detects overloading of the motor and interrupts power flow to the motor, thus preventing motor overheating and winding damage. In addition to overload, it also protects the motor from phase loss/fault and phase imbalance. The designing of an overload relay can be done with a heater coupled with generally closed connections that unlock when the heater gets too hot. The connection of the overload relay can be done in series or placed between the motor and the contactor itself to avoid restarting the motor in the event of an overload trip.