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Diffrence Between Mccb And Mcb


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#1 AB2005

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Posted 02 June 2007 - 05:20 AM

Hello

Can anybody explain me the difference between a MCCB (Molded Case Circuit Breaker) and a MCB (Miniature Circuit Breaker?). Usually, the MCCB is big in size as compare with MCB. Can we use MCB in the place of MCCB in light load applications?
Thanks for any input.

"Don't assume any thing, always check/ask and clear yourself".

#2 jraef

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Posted 03 June 2007 - 05:03 PM

Generally, the main difference (if the amperage is the same) is in the device's ability to withstand a fault. MCBs are only capable of very low available fault currents, Somewhere in the neighborhood of 5kA. So in most cases they must be used behind some kind of current limiting device. MCCBs on the other hand can usually be used in much higher fault current conditions.

Here in the US it gets more complicated because most of the MCBs are not UL listed as "circuit breakers" but as "Supplementary Circuit Protectors", meaning that they CANNOT be used unless they have some other device up stream, such as an MCCB, which makes them only useful when you have a lot of smaller downstream loads.
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#3 chaterpilar

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Posted 04 June 2007 - 02:12 PM

AB,

The shortcircuit rating is the prominent difference.

MCCB have have many times more fault-current rating, than MCB.

Hence MCB ( Miniature circuit breakers) are used on light loads, and help in fault-clearance at lower level.

chaterpilar

#4 AB2005

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Posted 05 June 2007 - 06:33 AM

My friends,
many thanks.

Now I have understood that the difference between these two circuit breakers is only the interrupt capacity against short circuit current. At lower level short circuit applications (5ka), we can use either MCCB or MCB-but MCB is cheaper than MCCB, so we use MCB.

"Don't assume any thing, always check/ask and clear yourself".

#5 jraef

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Posted 07 June 2007 - 04:02 AM

I think that is a good assessment.

"He's not dead, he's just pinin' for the fjords!"

#6 GGOSS

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Posted 08 June 2007 - 07:06 AM

Just to add some further clarification.

MCB = Miniture Circuit Breaker, used for domestic, light commercial and light industrial applications.

MCCB = Moulded Case Circuit Breaker used in heavy commercial and heavy industrial applications.

And as stated above fault current rating is greater, generally much greater with the MCCB eg:

MCB 4 to 16kA

MCCB 25 to 85kA and possibly greater.

#7 hung

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Posted 20 June 2007 - 10:23 AM

not really... if u search for 100A MCB... it could be expensive as it is not a norm size and not produce in mass... where as 100MCCB could be cheaper...


QUOTE(chaterpilar @ Jun 4 2007, 10:12 PM) View Post

AB,

The shortcircuit rating is the prominent difference.

MCCB have have many times more fault-current rating, than MCB.

Hence MCB ( Miniature circuit breakers) are used on light loads, and help in fault-clearance at lower level.

chaterpilar



#8 AB2005

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Posted 21 June 2007 - 03:30 AM

Hello Hung,

We are not talking about the hiegher raiting MCBs. Mostely, the MCBs are produced upto 63A. For more hiegher raiting, MCCBs are recommneded for use.
"Don't assume any thing, always check/ask and clear yourself".

#9 maxk

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Posted 24 February 2010 - 04:14 PM

QUOTE (jraef @ Jun 3 2007, 05:03 PM) <{POST_SNAPBACK}>
Generally, the main difference (if the amperage is the same) is in the device's ability to withstand a fault. MCBs are only capable of very low available fault currents, Somewhere in the neighborhood of 5kA. So in most cases they must be used behind some kind of current limiting device. MCCBs on the other hand can usually be used in much higher fault current conditions.

Here in the US it gets more complicated because most of the MCBs are not UL listed as "circuit breakers" but as "Supplementary Circuit Protectors", meaning that they CANNOT be used unless they have some other device up stream, such as an MCCB, which makes them only useful when you have a lot of smaller downstream loads.



To add some more info:
the withstand of current is different in Icu,Ics which defined in IEC60898 and IEc 60947-2.
  • MCBs are working in 60898 up to 125 A and 25 KA Max.
  • MCCBs are working in IEC947-2 up to 6300 A and 250 KA Max .
  • you can adjust current wrking of MCCBs and its overload beside short circuit selection.
  • MCBs are fixed in short circuit and load current and over load Curves.
  • Manily (depend on circuit) MCCBs are useing in up stream and MCbs in down stream.
  • accessories for each one differ usage of each one as MCCBs can control by Motor and Shunt trip relays and so on .
    there are some simple differences between them which is mainly mechanically.
  • We have ACBs which also defferents of MCCB in Usage and Current withstanding in Icw.


#10 AB2005

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Posted 03 March 2010 - 11:01 AM

QUOTE (maxk @ Feb 24 2010, 09:14 PM) <{POST_SNAPBACK}>
To add some more info:
the withstand of current is different in Icu,Ics which defined in IEC60898 and IEc 60947-2.
[*]Manily (depend on circuit) MCCBs are useing in up stream and MCbs in down stream.


Dear,

Thanks for info.
You have used some words Icu, Ics, up stream and down stream. Can you please explain about them?
Sorry i have a very little knowledge about them.
"Don't assume any thing, always check/ask and clear yourself".




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