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Relay

• An electrical control switch.

• Most relays use electromagnetics to change mechanical mechanisms,

but other operating principles are also used.

• Relays are used to control circuits by low-power signals (with

complete electrical isolation between the control and control circuits),

or where multiple circuits must be controlled by a single signal.

Contactor

• A contactor is an electrical control switch used to operate a
power circuit
• Its function is almost the same as a relay, but it handles high currents

• Contactors come in a variety of shapes with a varietyof capabilities

andfeatures.

• Contactors consist of breaking current of several ampere to thousands

of amperes and 24 V DC many kilovolts.

• The physical size of the contactor is quite small fromone hand, to large

devices about one meter.

• Contactors are used to control electric motors, bank capacitor heaters

and other electrical appliances.

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