What does an overload relay do in a motor protection system?

An overload relay plays a crucial role in motor protection systems by disconnecting the motor from the power supply when it detects that excessive current is flowing through it. This condition often arises due to an overload, where the motor is required to perform more work than it is designed for, leading to increased current draw that can cause overheating and potential damage.

When the overload relay senses this excessive current, it activates a trip mechanism that interrupts the power supply to the motor. This protective feature prevents overheating, reduces the risk of insulation failure, and prolongs the lifespan of the motor. Hence, the primary function of the overload relay in a motor protection system is to safeguard the motor against unfavorable operating conditions by ensuring that it operates within its designed current limits.

The other options present functions that are not related to the primary role of an overload relay. For example, increasing the motor’s operating voltage, controlling its speed, or providing an alternative power source during failure are not functions performed by an overload relay. Instead, these tasks may be managed by different components or systems designed specifically for those purposes.