An overload relay is an electrical device that is used to protect electric motors from damage due to excessive current. When a motor is running, it draws a certain amount of current, which is determined by the load it is driving. However, if the load becomes too great, the current drawn by the motor will increase beyond its rated capacity, which can cause overheating and damage to the motor.
An overload relay is designed to detect this excessive current and interrupt the power supply to the motor, thus preventing damage. It works by monitoring the current flowing through the motor and comparing it to a predetermined set point. If the current exceeds this set point, the overload relay will trip and open the circuit, stopping the flow of power to the motor.
Overload relays are commonly used in industrial and commercial applications, where electric motors are used to drive heavy machinery and equipment. They are typically installed in motor control centers, which are electrical panels that house the switches, fuses, and other devices used to control the operation of electric motors.