Relays are electrical switches that turn machinery and devices on or off. They help keep equipment running smoothly in automotive, industrial, and telecommunications applications. Plug-in relays are used when a machine must control a circuit with a lower-power signal or when several circuits must be controlled with one signal. Arc flash, current sensor, and voltage sensor relays detect changes in power to protect machinery from damage. Alternating relays alternate the operation of two loads. Safety monitoring relays respond to hazardous conditions to keep workers safe. Time-delay relays open or close contacts at specific times. Wireless relays and transmitters switch machinery on and off from various locations. Accessories and sockets are used to maintain, repair, and enhance the capabilities of relays.