Relays

thumb|A relay thumb|Electromechanical relay principle thumb|Electromechanical relay schematic showing a control coil, four pairs of normally open and one pair of normally closed contacts thumb|An automotive-style miniature relay with the dust cover taken off

thumb|Tesys D Schneider Electric Contactor A contactor is a type of relay (electrically operated switch) with high power rating (current rating and voltage rating). Contactors usually refer to devices switching more than 15 amperes or in circuits rated more than a few kilowatts. Contactors are typically used to control electric motors (combination motor starters), lighting, heating, capacitor banks, thermal evaporators, and other electrical loads. The physical size of contactors ranges from a device small enough to pick up with one hand, to large devices approximately a meter on a side.

safety device for oil-filled electrical transformers

electronic switching device in which a small control signal controls a larger load current or voltage

devices that generally implement safety functions

relay device designed to trip a circuit breaker when a fault is detected

electromagnetic relay employing a reed switch

computer-based system with software-based protection algorithms for the detection of electrical faults

relay using mercury metal