elmorseyma
Member
Is there any relation between main MCCB (3 phase) in electrical panel and distribution MCBs (1phase) or main MCCB dimension to total power drown directly
Main CB in low voltage distribution panels
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mdshunk
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Are you asking about the physical dimensions of the breaker? If so, there are "frame sizes" that are a de facto functional limit to the total ampacity of the breaker, above which you jump up to the next physical frame size.
elmorseyma
Member
I asked about rating ampare size of MCCB
I am also unsure of your question.
Every thing I can think of you likely already know.
The main CB needs be size to handle the load and protect the panel.
The branch CBs need to be sized to handle the load and protect the branch circuit conductors.
And although not always required, it is nice if the main and branch CBs are coordinated. Is this the thing you are questioning? Some times this is hard to do if the equipment is molded case CB and the available SCC is up in the instaneous rating of the main CB
carl
edited to clarify last paragraph
Every thing I can think of you likely already know.
The main CB needs be size to handle the load and protect the panel.
The branch CBs need to be sized to handle the load and protect the branch circuit conductors.
And although not always required, it is nice if the main and branch CBs are coordinated. Is this the thing you are questioning? Some times this is hard to do if the equipment is molded case CB and the available SCC is up in the instaneous rating of the main CB
carl
edited to clarify last paragraph
Last edited:
one other thought:
Perhaps are you asking about the sum of the branch CB ratings add up to way more than the main CB?
If so, that's okay. The panel just has to handle the connected load, which is generally significantly lower than the sum of all the branch circuits.
carl
carl
Perhaps are you asking about the sum of the branch CB ratings add up to way more than the main CB?
If so, that's okay. The panel just has to handle the connected load, which is generally significantly lower than the sum of all the branch circuits.
carl
carl
elmorseyma
Member
I think we should sum the branch MCBs (excluding spares) and multiply in 0.8 (load factor of each MCB).
After that we multiply in 0.8 (demand factor), then the resultant is the rating of main MCCB.
M Ali
After that we multiply in 0.8 (demand factor), then the resultant is the rating of main MCCB.
M Ali
Continuous Load?
Continuous Load?
Is your load always on and are all the Cb's sized for the load or do you have a bunch of 2A loads on 15A circuit breakers? the point is that your method is way too conservative for most installations. it would be an over engineered solution and not necessary unless you have a bunch of loads you know are going to be running all the time.
Continuous Load?
Is your load always on and are all the Cb's sized for the load or do you have a bunch of 2A loads on 15A circuit breakers? the point is that your method is way too conservative for most installations. it would be an over engineered solution and not necessary unless you have a bunch of loads you know are going to be running all the time.
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- San Francisco Bay Area, CA, USA
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- Electrical Engineer
I think it is important to note that by virtue of the OPs use of the terms "MCB" (Mini Circuit Breaker), he is NOT in North America, so the codes involved will not necessarily be the same as they are here.
elmorseyma,
I think it is important for you to discuss this with someone familiar with the electrical codes and regulations in whatever country you are in. We here in N. America have rules and guidelines based upon our National Electric Code (or the Canadian Electric Code, which is virtually the same), which may or may not have as much direct reference to theoretical engineering practice as you may think.
elmorseyma,
I think it is important for you to discuss this with someone familiar with the electrical codes and regulations in whatever country you are in. We here in N. America have rules and guidelines based upon our National Electric Code (or the Canadian Electric Code, which is virtually the same), which may or may not have as much direct reference to theoretical engineering practice as you may think.
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