Circuit Breaker.
This page describes a simple circuit
breaker.
See the next
page for the residual current
circuit breaker.
The circuit
breaker acts as a safety device
in the same way as a fuse.
Circuit breakers used in the distribution
board (called the consumer unit)
in houses are called MCBs
(minature circuit breakers).
They disconnect the supply if too large a
current
flows.
When the live wire carries the
usual operating current
the electromagnet is not strong enough to
separate the contacts.
If something goes wrong with the
appliance and a
large current flows
the electromagnet will pull hard enough
to separate the contacts and break
the circuit.
The spring then keeps the contacts apart.
After the fault is repaired,
the contacts can then be pushed back together
by lifting a switch on the outside of the circuit breaker.
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