mccb:moulded case circuit breaker used as an incomer to any
panel,mccb can be used till 1000A beyond that acb & vcb are
used,acb=>3000A at 440v low tension side
vcb=>3000A > 6.6kv,11kvat medium voltage side
sf6=>6000 > 66kv,110kvat high voltage side
mccb is moulded case circuit breaker, is used in power
cicuits to provide isolation for circuit from high current,
short circuit and earth fault. but mccb only can use in low
current cases at 440volts.
acb is air circuit breaker, can also use in power circuits
to provide isolation in those same cases. but in high
current cases at 440volts with more functions.
vcb is vaccume circuit breaker. it is for high voltage
cases like 11kv, 33kv etc with more function than acb and
same reason of application.
the main difference is mccb means moulded case circuit
breaker which use ark
quenching device as AIR which is used upto 500 Amps only
ACB:air circuit breaker which use quenching device as air
and used upto 3000 Amps at 415 volts
Mccb is not having a long life ACB is having long life
MY QUATION IS ABT THE MAIN POWER TRANSFORMER IN STEEL
PLANT , I WISH TO KNOW THAT WHY TRANSFORMER PROTECTION NOT
TRIP AS CABLES ON THE SECONDAY SIDE IS WATER COOLED.
NORMAL KVA--150 KVA
PRIMARY VOLTAGE --34.5 KV
SEC.NO-LOAD VOLTAGE---1.290-908-690V ( WITH PRIMARY DELTA
CONNECTION--D/d (EXTERNAL CLOSED)
CONSTANT RATEING FROM--1.290-908V
CONSTANT CURRENT FROM--908-690
VECTOR GROUP--D III