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IAC Classification - Internal Arc - HV Switchgears above 1kV and up to 52kV - EN 62271 - 200

vici
Hi everyone,


I wondered if you could help with the follwong question about how to determine the IAC rating in kA.


If the maximum expected three phase fault in rms is 20kA at a 11kV switchgear, would it be sufficent a IAC rating of 25kA for 1s or a higher rating should be selected? If higher IAC raing in kA should be opted for, what would be the reason?


Thank you.

  • 0
    From my understanding of the standard, the IAC rating is not measured in kA, but rather it is stated as A, B or C following the test with a defined test current in kA.

    I would expect the test current and the duration to be selected based on the short circuit fault current and the clearance time of the protective devices. Therefore in the situation you describe I would consider 25kA to be a suitable test current and, assuming the clearance time of the circuit breakers is less than this, a duration of 1 second to be suitable.

    Alasdair

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