What is the difference between Relay and Contactor

Answer Posted / akshay pramod

1) A contactor is an electro-magnetic switching device (a
relay) used for remotely switching a power or control
circuit.[1] A contactor is activated by a control input
which can be a lower or higher voltage / current than that
which the contactor is switching. Contactors come in many
forms with varying capacities and features. Unlike a
circuit breaker a contactor is not intended to interrupt a
short circuit current.

Contactors range from having a breaking current of several
amps and 110 volts to thousands of amps and many kilovolts.
The physical size of contactors ranges from a device small
enough to pick up with one hand, to large devices
approximately a metre (yard) on a side.

Contactors are used to control electric motors, lighting,
heating, capacitor banks, and other electrical loads.

2) A relay is an electrical switch that opens and closes
under the control of another electrical circuit. In the
original form, the switch is operated by an electromagnet
to open or close one or many sets of contacts. It was
invented by Joseph Henry in 1835. Because a relay is able
to control an output circuit of higher power than the input
circuit, it can be considered to be, in a broad sense, a
form of an electrical amplifier...

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