An automatic relay is an electrically operated switch used to control the flow of current in a circuit. Unlike manual switches that require human intervention, automatic relays work autonomously to control various functions, such as turning devices on or off, regulating current flow, or protecting electrical systems from overloads. They play a vital role in ensuring the reliability and safety of electrical networks by detecting fault conditions and triggering protective measures.

    The design of automatic relays typically involves a coil that, when energized, creates a magnetic field, which in turn activates the relay’s switch. This action can either complete or break a circuit, depending on the relay's configuration. The ability of automatic relays to respond to changes in electrical parameters, such as voltage, current, or frequency, makes them indispensable in modern electrical systems.