A switch relay is an electrical device that uses an input signal to control the operation of an output circuit. Essentially, a relay acts as a switch, allowing a low-power signal to control a higher-power circuit. The switch relay operates by receiving a control signal (either voltage or current) that energizes its internal components. Once energized, the relay changes the state of its contacts, either opening or closing the circuit, allowing or interrupting the flow of electricity to a connected load.

    Switch relays are widely used in various systems where a control signal is required to operate heavy electrical equipment. They are vital in isolating control circuits from high-voltage systems, providing a safe interface between low-voltage control systems and high-voltage machinery.