Kindly through some light on how to
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Kindly through some light on how to

Mehak kar (Mechanical)

(OP)

2 Dec 23 18:55

Kindly through some light on how to calculate the breaking current capacity of a MCCB?

davidbeach (Electrical) · Answer 1 · 2023-12-02 22:28:43

You don't calculate it, you read it off the nameplate. The relevant IEEE or IEC standard may then provide guidance for adjusting that rating (downward) when the prospective fault current X/R exceeds the test value.

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Gr8blu (Electrical) · Answer 2 · 2023-12-04 13:05:33

Breaking capacity formula (does not matter what type of breaker is used).
BC = 1.732 * V * A * 10E-6

BC is breaking capacity in MVA
V is the rated service voltage in volts
A is the short circuit current in amperes

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che12345 (Electrical) · Answer 3 · 2023-12-04 23:42:32

Mehak kar (Mechanical)(OP)2 Dec 23 18:55
" Kindly through some light on how to calculate the breaking current capacity of a MCCB?"
The learned advice by Mr. davidbeach is short and sharp. A great post.
I would like to add the following for clarity, for your information.
1. In the IEC world, a) rated ultimate short-circuit breaking capacity (I_cu,..is the maximum short-circuit current value which the CB can break twice (O-t-CO) at the corresponding rated operational voltage. After the opening and closing sequence, the CB is [b]NOT required to carry the rated current.
b) Rated service short-circuit breaking capacity (I_cs), ..._is the maximum short-circuit current value which the CB can break three times in accordance with a sequence of opening and closing operation (O-t-CO-t-CO) at a defined voltage of (I_e) and at a defined power factor. After the sequence, the CB is required to carry its rated current.
2. Note: a) Testing procedure and judgment differ between IEC (in Europe) and IEEE/NEMA (in US). The same CB rated X kA per IEC is very likely to be rated Y kA per IEEE/NEMA.
b) This result to test certification or EC mark in Europe is NOT automatically as being listed/recognized by UL in the US.
3. IEC in (Europe) and IEEE/NEMA (in US), each publishes/issues their own "standard" without any co-ordination or harmonisation.
4. The IEC and IEEE/NEMA do NOT carryout any testing or policing that their "standard" is correctly implemented/interpreted.
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Kindly through some light on how to
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