What is the primary function of a motor overload relay?

The primary function of a motor overload relay is to protect against overheating. This device is designed to monitor the amount of current flowing through a motor and will trip when the current exceeds a pre-set threshold, indicating that the motor may be drawing too much power and is at risk of overheating. Overheating can lead to insulation failure, damage to the windings, and ultimately, motor burnout. By interrupting the circuit and stopping the motor operation when an overload condition is detected, the relay prevents thermal damage and extends the lifespan of the motor.

The focus on current is essential because motors are typically designed to handle specific current levels, which reflect their load capacity. When a motor operates beyond this capacity, the overload relay activates, providing critical protection to the equipment and ensuring safe operation. This function is vital in industrial settings where motors are regularly subjected to varying loads and conditions.