high voltage transmission, Relay

RELAY

The
relay is used to control a large current with the help of a small current. A
relay is an electrical switch that opens and closes under the control of
another electrical circuit

The 1st circuit (input circuit) supplies
current to the electromagnet. The electromagnet is magnetized and attracts one
end of the iron armature.

The armature then closes the contacts
(2nd switch) and allows current to flow in the second circuit.

 When the 1st switch is opened again, the
current to the electromagnet stops.

Now electromagnet loses its magnetism and
the 2nd switch is opened. Thus, the flow of current stops in the 2nd
circuit.

Some other examples of the magnetic effect of an electric current are
loudspeaker, circuit breaker and door latches.