Advantages of ACB over MCCB

ACB, or as they are more commonly known today Low Voltage Power Circuit Breakers, are used for interrupting higher currents (above 800A). Molded Case Circuit Breakers are used for lower interrupt ratings and cost far less.

Since a Molded Case Circuit Breaker extinguishes the arc in air it is considered an air circuit breaker.

I agree with the previous response - I interpret your inquiry as what is the difference between an Low voltage Power Breaker (LVPB) and a Molded Case Circuit Breaker(MCCB).

LVPB are build to ANSI standards and are listed to UL 1066, MCCB are listed under UL489. I have no idea how the IEC standard distinguishes these breakers

The difference is in the testing. The main advantage to the LVPB is the 30 Cycle withstand rating that is a part of the UL 1066 listing. This breaker can withstand a high short circuit for up to 30 cycles and give a downstream device time to clear the fault. Many designers like to use LVPB as a main ahead of MCCB for this reason. Other designers just incorporate this feature into there overall short circuit and coordination study. UL 489 MCCB are not required to undergo this test.

Another advantage of the LVPB is it is serviceable. These breakers can be reconditioned with replaceable contacts, arc chutes, and other and parts readily available.

The disadvantage of LVPB is they are big and require a lot of space. You vary rarely see them below 800 amps

Generally ACBs are inteligent (miccroprocessor), Higher short ciircuit rating (KA rating), of higer current carring capacity, motorised, and more rogged. both ACB & MCCB have air queching medium. those there are motorised mccb, but with mischivious performaces.

There are so many thing advance future in ACB than MCCB,

1) selection of tripping curves in ACB are (In, Ir, Inst/MCr, ST, LTD, GFT & PTA).

2) Making & breaking time.

3) Ampere rating, Arc chamber, KA rating & etc

4) ACB Acc. more loaded than MCCB.

5) ACB used as a Master Breaker on Incoming Side, and MCCB are used as a feeder Circuit Breakers.

6) ACB Mechanical & electrical life is more than MCCB.

And many more advance futures in ACB.

Regards,

Habib Haider.

Jubilee Corporation Pakistan.

But can we describe the principle difference between ACB & MCCB.

we can distinguish the ACB & MCCB as ,

1. ACB due to its time withstanding capacity (Isw) feature ,comes in 'B' category

2.Though MCCB has not Isw feature , i comes in 'A' category.

now please refer the below example :

We can use both MCCB Or ACB as an incomer for the same rating but for big industries where small load shedding means crores of loss ,there we must use only ACB's .

during the course of short circuit ,MCCB's will trip the load instatniously but ACB due to its 'Isw' feature, will hold the Shortcircuiting current for seconds which will be sufficient to go for secondary option .During that course of time a signal may be given to the genset and we may get the continuous supply without loadshedding .

In MCCB we can have only two auxillaries but in case of ACB ,we can have n-number of auxillaries .

Moreover MCCB's are not repairable ,where as we can repair ACB's