How does MCB operate without relay..?

Answer Posted / j. r. gaikwad

Relay is name given to a mechanism which changes the
position of a switch under certain predetermined condition
e.g.excess load , excess current , under voltage , over
voltage etc.
MCB contains electromagnet operated switch to trip under
short circuit state ( as it operates insantaneously , this
is necessary under shortcircuit condition ) & a thermal
over load relay i.e. a switch operating because of bending
of a Bimetal strip at higher temp produced by the excess
heat produced by the excess current - due to over load .

MCB simply means "small" circuit breaker .It does contain
mechanism to trip , i.e. switch automatically under adverse
conditions !

This is the right answer.

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