DEFINITION
A device capable
of making and breaking of an electric
circuit under normal and abnormal condition
BASIC FUNCTIONS
To make, carry
and break the normal services current.
To continuously
monitor the current flowing in the circuit and to protect the system by
tripping when there are overloads or short-circuits in the system as
quickly as possible to minimise effects of short circuits and overloads
Types of Circuit Breakers
l Miniature Circuit Breakers (MCBs)
l Moulded Case Circuit Breakers (MCCBs)
l Air Circuit Breakers (ACBs)
l Bulk Oil Circuit Breakers (OCBs)
l Minimum Oil Circuit Breakers (MOCBs)
l SF 6 Breakers
l Vacuum Circuit Breakers (VCBs)
Main Breaker Specifications
l Rated Normal Current – R.M.S. value of current that the
breaker can carry continuously with
the temp. rise in the current carrying parts within 40-50
C.
l Making Capacity- Maximum (fault) current on which the
breaker can make without incurring any damage to itself.
Expressed in Peak value of
making current in KA.
l Breaking Capacity- Maximum (fault) current which the breaker
can break without incurring any damage to itself.
Expressed in RMS value
in KA/MV
General Maintenance of Breakers
l Cleaning of contacts
l Lubricating moving parts
l Checking Dielectric strength of
oil/renewal of oil (OCBs only) .Periodic check
for manual/electrical close/trip operations and for tripping through protective
devices with breaker in “Test” position
CIRCUIT BREAKER
Reviewed by HODO
on
September 29, 2017
Rating:
Reviewed by HODO
on
September 29, 2017
Rating:
