Short Circuit - Breaking Current

This "Cahier Technique" reviews the calculation methods for short-circuit currents as laid down by standards such as IEC 60909. It is intended for radial and meshed low-voltage (LV) and high-voltage (HV) circuits.

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If your transformer is 1500KVA with 5% impedance.

You can go with this method....

FLA = 1500(kva)X1000 / 1.732X415(volt)X0.9 =2086A

Z=5%..... 100/5 = 20

KA = 2086X20

41720 Amps (41KA)

Thanks

You want to calculate the "Breaking current". Others have told you how to calculate the "Prospective SC current".

i assume you mean that "having designed a circuit breaker, i want to calculate its breaking capacity"...if this is your question, then i am afraid that this is like the holy grail, we are all in search of it. Many companies are doing advanced research, using CFD, FEA and, of course, lots of testing. But no holy grail yet

What i meant here, Asghar, is that : when you design a circuit breaker, you cannot predict what current it will break. Most top switchgear companies have been striving to create some software to simulate this, and some have achieved some success....here is an image from a paper by Schneider Electric....

and another from a research institution from Czechoslovakia....

i am now retired, so i have no idea whether the research that was going on when i was there, in ABB and GE, has reached anywahere. i am sure that they have made considerable progress. But nobody has said that they have now a solution...

So, i believe it is still perhaps akin to the pursuit of the holy grail