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A relay is a type of electromagnetic switch, similar to a contactor, that can be controlled remotely with electricity, rather than needing manual input as a standard switch would.

CONTROL RELAYS

Relays can be used to control normal loads, as a contactor would, however the benefit of a relay is they come with multiple normally-open (N.O.) and multiple normally-closed (N.C.) contacts – allowing you to use it to power some things on, while removing power from others at the same time.

The reason they are often called “control-relays” is because they’re typically used at lower voltages/lower amperages to control other devices such as contactors which are normally higher voltage and higher current. Many times you’ll find a control relay being controlled by smaller electronic circuits, events, or programs. When an electric signal is sent to engage the coil inside, it can send power to other devices which can turn them on or off – or both simultaneously.

 

THE COIL

On the inside of a relay you’ll find a coil of wire around two pieces of metal. When we send current through that coil of wire, the two pieces of metal suck together through electromagnetism. These pieces of metal that are opening or closing, are the “switch” for the relay to turn on and off.

Coils come in many different voltage ratings. There are many types of coils out there that are controlled at 12-volts, 24, 120, even up to 240. However, the amount of current (amps) that the contacts can handl

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