The overload relay is wired in series with the motor, so the current that flows to the motor when the motor is operating also flows through the overload relay. It will trip at a certain level when there is excess current flowing through it. This causes the circuit between the motor and the power source to open. The overload relay can be manually or automatically reset after a predetermined time duration. The motor can be restarted after the cause of the overload has been identified and rectified.