Answer / anushil

basically by nature of work all are circuit breaker,though selection of CB depends upon the amount of load drawn & potential in line to which breaker needed.as all three have different quenching medium,like (air, vaccum etc)now selection of breaker depends on dielectric strength or quenching medium.
as air is medium for ACB & vaccum for VCB and their dielectric strength are 10^-5torr & 10^-8torr respectively. so VCB have more dielectric strength then compare to air. as because of that selection of breaker depends on the dielectric strength of medium.


ACB (air circuit breaker-630,800,1000,1200,1500,2000,2500,4000,5000 Amp here curent rating is high but voltage is low)is used for LT(415 Volt) Panels as amount of arc generate in breaking of contact is low& strenght needed is 10^-8 torr. now for VCB(vaccum circuit breaker)is used for HT(6.6,11,33KV) Panels as amount of arc is more so we need at least dielectric strenght of 10^-5Torr.

Answer / deva nand

MCCBs:
Rated current up to 3200 A.
Adjustable tripping thresholds.
Magnetic or thermal-magnetic operation.
Trip units can be magnetic, thermal-magnetic or electronic.
Most MCCBs have utilisation category "A".
MCCBs in general are less expensive than ACBs.

ACBs:
Rated current up to 6300 A.
Adjustable tripping thresholds.
Thermal-magnetic operation. Trip units can be thermal-magnetic or electronic.
Most ACBs have utilisation category "B" which means that it has an "Icw" value which is the rated short-time withstand current.
ACBs are more expensive than MCCBs.

Answer / saad

Its absulotely aboolshit issue to talk about it by this much

Answer / p.sivaraja

MCCB& Acb are using Lt(440v) level loads.vcb's are using
HT(Above 11000v) level load.MCCB&ACB are isolators its
tripped by external devices eg; thermal magnetic
realse&Micro Proceeser release,SHuntcoil uv coil.
Now days mcb are using upto 125amps,MCCB'S are 18amps to
1250amps,ACB'S are 800amps to 6000amps,vcb's are kv

Answer / kather oli

MCCB ACB VCB
100A TO 800A 800A TO 4000A UP TO 4000A

LT LT HT

ARC QUEANCE ARC QUEANCE ARC QUEANCE

LOW PLACE < PLACE < PLACE (HT)

BIMETALIC AIR VACUM

LOW COST < COST < COST

NOT CHARGER CHARGER CHARGER

Answer / d.emerson dhansingh

Answers 1-10 except perhaps,9 are true in parts but do not provide a complete answer to the question.

All three of them are meant for making or breaking an electrical circuit under normal and abnormal (fault) conditions, unlike switches and isolators which are not designed to withstand fault currents

All of them have different short circuit interrupting capacity, MCCB being the least(upto 85 KA)followed by ACB (upto 125 KA) and VCB (>125 KA). They are selected for use in an Electrical circuit as decided by the max.fault levels 
that are possible at the point where they are used.

All of them can be mechanically or electrically switched "on" and "off" and they can be automatically tripped on fault conditions.

All of them can be provided with Adjustable "Thermal" and "Magnetic" trips for protecting the circuits against "Overload" and "Short Circuit" 

The method and medium of arc quenching used in these breakers differ from each other.

Of all the three breakers, VCB is more popular and preferred over others in HT (largely) and LT for the following reasons.

1. VCBs can easily be called as "zero maintenance" breakers
2. For the same current rating, VCBs are smaller in size.
3. It is  "eco-friendly" in operation.
4. The contact wear is minimal and that results in longer      operating life

The capital cost in installing VCBs are the highest but the operating and maintenance costs are the lowest.

The above are only the most important features of these breakers but there are many constructional differences as well.

D E Dhansingh
Electro Technical Officers Programme
Ethiopian Maritime Academy
Bahir Dar University, ETHIOPIA

Answer / d e dhansingh

All the said breakers havet their own rupturing capacity (
ability to break the prospective short circuit level) and
are used accordingly.

MCB is Miniature Circuit Breaker which has a rupturing
capacity of 10KA and is used for lighting and other
circuits where the short circuit levels are below 10 KA

MCCBs or Moulded case circuit breakers have a rupturing
capacity of 80 KA

ACBs or Air circuit breakers have a rupturing capacity upto
120KA

VCBs are vacuum circuit breakers which are extensively used
in LV & HV circuits because of their advantages like a
longer operating life and lower erosion of contacts.

Answer / v. k. vishwakarma

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.

Answer / arun

first... ACB means AIR CIRCUIT BREAKER>>????
ITS A AIR BREAK CIRCUIT BREAKER,,..

Answer / pankaj kr. gupta

MCCB is MOLDED CASE CIRCUIT BREAKER
ACB is AIR CIRCUIT BREAKER
VCB is VACCUM CIRCUIT BREAKER

VCB is MORE PROTECTIVE IN COMPERSION TO ACB
THEREFORE WE USE VCB IN HT SYSTEM FOR MORE PROTECTION.

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