A switch relay is an electromechanical device that opens or closes a set of contacts under the control of an electrical signal. Essentially, it acts as a switch that can be operated remotely by an electrical input, which typically involves using a low-power signal to control a high-power circuit. Relays have been an integral part of electrical engineering and control systems for decades because they enable the remote control of devices that would otherwise require direct human intervention.

    A typical relay consists of a coil, an armature, and contacts. When current flows through the coil, it creates a magnetic field that attracts the armature, causing it to move and either open or close the contacts, depending on the design of the relay. This action allows the relay to control the flow of electricity in the circuit.