typically, a circuit diagram breaker is ahead of the contactor, and an overload is attached or directly behind a contactor/motor starter in the circuit. Motor protector circuit breakers are available that cover the CB/fuse and motor overload needs in one convenient device.

Overload protection relays prevent motor damage by monitoring the current flow in the motor circuit and breaking the circuit when an electrical overload or a phase failure is detected. Since relays are much cheaper than motors they provide an affordable way of protecting of the motors.

Motor overload occurs when a motor is under an excessive load. The primary symptoms that accompany a motor overload are excessive current draw, insufficient torque, or overheating. Excessive pump heat is a major cause of motor failure.

The overload of a 3-phase asynchronous motor means that the current flowing through the motor exceeds the rated current flow within a certain allowable time.

Starters - Most electric motor starters have an overload of protection built in in the form of an overload relay. When an overload situation occurs, the starter trips and the power supply is removed from the circuit. Starters are great for motors that only require start or stop control, but not speed control.