How does an overload relay protect electrical circuits?

An overload relay protects electrical circuits primarily by automatically disconnecting power when it detects excessive current flow. When the current exceeds a predetermined threshold, the relay's mechanism activates, which opens the circuit and isolates the load from the power source. This action prevents overheating of wires and components, which could lead to insulation damage, potential fire hazards, and equipment failure.

The functionality of an overload relay is based on the principles of heat generation due to current flow; as current increases, so does heat, and this thermal effect is closely monitored by the relay. When the heat reaches a certain level, indicating too much current is flowing, the relay trips and breaks the circuit. This protective measure is crucial in maintaining safe operational conditions, thus preserving the integrity of the electrical system.