MCCB vs ACB
MCCB vs ACB
(OP)
What is the difference between a MCCB and ACB / MCB ?
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RE: MCCB vs ACB
Donald G. Fink, H. Wayne Beaty "Standard Handbook for Electrical Engineers," 14th Ed., McGraw-Hill, 2000,
page 10-84
Air Circuit Breaker
Briefly, ACBs resemble switchgear. They are applied as switchgear in switchgear housing or switchboards.
Molded-Case Circuit Breaker
MCCBs are completely enclosed within a ruggedly constructed molded case of insulating material.
Often available from 15A to 4000A, 1-, 2-, 3- and 4-poles, 5kA to 45kA Isc and high interrupting ratings up to 200kA.
Also, refer to manufacturers' catalogs.
RE: MCCB vs ACB
Basically the LVPCB is a more heavy-duty breaker than a molded-case breaker. They are built to different standards (ANSI C37) and are more flexible in application. LVPCB are field-maintainable, MCCBs are not.
LVPCBs have a short-time withstand rating that allows them to be applied without any instantaneous trip. Molded case circuit breakers must have instantaneous trips. This means that MCCBs are impossible to coordinate for high levels of fault current.
Probably the most informative thing to do is to go to a manufacturer's website and look at some pictures. You'll see a big difference in size and configuration. (and cost, of course.)
RE: MCCB vs ACB
http://www.squared.com/us/products/circuitb.nsf/Documen...
for Micrologic Trip Systems
RE: MCCB vs ACB
Thread238-19242
Thread238-63358
Per UL, MCCB's and ICCB's must have instantaneous trip functions to protect the circuit breaker itself. All UL listed MCCG's and ICCB's have an 'instantaneous override" function, meaning when the current reaches some pre-set level the breaker trips instantaenously, regardless of trip settings. ANSI power circuit breakers do not have instantaneous override.
This gets a little fuzzy when discussing products such as the Square D Masterpact and Cutler-Hammer MagnumDS, which can be ordered as either an ICCB (UL489) or ANSI power breaker (UL1066). With these you must specify which version you want.
RE: MCCB vs ACB
MCB(Miniature Circuit Breaker)is used for handling small load.For example lighting load.It is available for a maximum short circuit capacity of 10Kilo Amp.It also has instantaneous and overload tripping devises,but these setting are fixed i.e. factory set and can not be changed.
More information you can have from the manufacturer's catalogue.
RE: MCCB vs ACB
RE: MCCB vs ACB
RE: MCCB vs ACB
The short circuit coordination is actually performed via the short-time delay band since the instantaneous band doed not have any delay available.
RE: MCCB vs ACB
http://ecatalog.squared.com/pubs/Circuit%20Protection/L...
http://ecatalog.squared.com/pubs/Circuit%20Protection/I...
Notice the UL489 version is called "insulated case circuit breaker", and the ANSI version is called "low voltage power circuit breaker".
UL489 circuit breakers (MCCB/ICCB) are for use in UL891 rated "switchboards", whereas ANSI rated circuit breakers (ACB) are for use in ANSI C37 "low voltage power switchgear"
This discussion applies mainly to U.S. standards.
RE: MCCB vs ACB
In opposite to this, ACBs do not limit the (peak) short circuit current. That means, that a switchgear that is connect to a transformer via an ACB has to be rated for the full short circuit current (e.g. 50kA for 1600kVA 400V transformer, regarding also motor load) while it can be designed to a lower short circuit current (e.g. 35 kA in this case) when it is connected via an MCCB.
RE: MCCB vs ACB
Reference:
UL Component Recognized Series-Connected Ratings and CSA Certified Series-Rated Combinations, DET008B by GE Industrial Systems, available on:
http://www.ge.com
RE: MCCB vs ACB
It is an insert from IEEE Std 1015-1997 - IEEE Recommended Practice fo Applying Low Voltage Circuit Breakers Used in Industrial and Commercial Power Systems. You should find you answers there.