How to calculate the breaking capacity(like 15ka,20ka) of
Circuit breaker (MCB,MCCB,ACB)
Answers were Sorted based on User's Feedback
Answer / shan80
it depend upon the value of current flows during short
circuit.
And the short circuit current depends upon the KVA rating of
transformer how supplies that particular load and transformer
percentage impedance.
Is This Answer Correct ? | 56 Yes | 15 No |
Answer / jitesh patel
we must know load of perticular equipment.
For Ex. Our load in MVA is 50 MVA
Our system voltage(MCB,MCCB,ACB) is 440V.
I(Bre)= 50/(1.73x0.440)=65.6 =Approx 65KA.
Our load in MVA is 20 MVA
Our system voltage(MCB,MCCB,ACB) is 440V.
I(Bre)= 20/(1.73x0.440)=26.2 =Approx 25KA.
Is This Answer Correct ? | 79 Yes | 50 No |
Answer / mohammed rafi
All above said suggestions are mere copy paste of something from wiki answer.its totally wrong.
Aforesaid calculations are to calculate rated current.
Short circuit analysis is to be done to calculate breaking capacity.
Is This Answer Correct ? | 11 Yes | 3 No |
Answer / ranadhir roy
We need to find out the short circuit MVA & based on this shortcircuit MVA , we need to calculate shortcircuit current .
Is This Answer Correct ? | 2 Yes | 0 No |
Answer / sunil sethi
All are ok, but In industries generally 5MVA transformer they are using for a company load, then if we consider 5MVA is our load then Icu is 5/(1.732x440)=0.0065ka , please clarify, Is it ok please answer .
Is This Answer Correct ? | 2 Yes | 3 No |
Answer / t s gupta
Breaking Capacity of MCCB is pre-calculated permissible amount of fault current (value of current can flow from contacts before opening/tripping the MCCB without damaging) which may facilitate the safe operation of MCCB and distribution transformer both.
It shall be calculated/derived from the distribution Transformer MVA rating and %impedance = kVA*100/ system voltage of load side * % Impedance rating
e.g. 20 kVA transformer with 5% Impedance, secondary voltage 440V i.e. 0.440 kV
Fault current Isc = 20*100/.440*5 = 10kA approx.
Is This Answer Correct ? | 0 Yes | 1 No |
Answer / hrusikesh dehury
we must know load of perticular equipment.
For Ex. Our load in MVA is 50 MVA
Our system voltage(MCB,MCCB,ACB) is 440V.
I(Bre)= 50/(1.73x0.440)=65.6 =Approx 65KA.
Our load in MVA is 20 MVA
Our system voltage(MCB,MCCB,ACB) is 440V.
I(Bre)= 20/(1.73x0.440)=26.2 =Approx 25KA.
Is This Answer Correct ? | 14 Yes | 24 No |
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