How does an overload relay protect a motor?

An overload relay is designed to protect electric motors from overheating and potential damage due to excessive current. When the operating current of the motor exceeds a predetermined threshold, indicating that the motor is overloaded or experiencing a fault (such as jamming or binding), the overload relay will trip. This means it will disconnect power to the motor, effectively stopping its operation and preventing further damage that could be caused by overheating.

This protective mechanism is crucial because motors are not built to handle prolonged overcurrent conditions, which can lead to insulation breakdown, overheating, and ultimately motor failure. By disconnecting the power, the overload relay ensures the longevity and reliability of the motor in the HVACR system. The other options do not accurately describe the function of an overload relay: increasing the motor speed, adding resistance to the circuit, or cooling the motor do not provide the protective function that the relay is designed for.