Short Circuit Capacity

fattony · 29 Apr 2009

Just a quick one, I forgot to note the Short circuit capacity of the MCB's today and checked through the OSG, would it be fair to assume that a type B MCB is 6KA and a type C MCB 10K or can they both vary?

Spark123 · 29 Apr 2009

No, they can vary. Look for the figure in the box or one preceded by the letter M.

fattony · 29 Apr 2009

mmm they are wylex MCB's some 3 phase and some single phase, the only writing on the MCB was NSB-B and the current rating on the 3 phase MCB's. The figure must be written on the side which is a little inconvenience.

Adam_151 · 29 Apr 2009

NSBs are 6Ka AFAIK

Shouldn't you be using PSBs in a 3 phase board?

Spark123 · 29 Apr 2009

NSBs are 6ka
PSBs are 10KA
It depends on what the PFC is and wether or not there is backup protection.

Adam_151 · 29 Apr 2009

I wasn't sure if that was the only difference between NSBs and PSBs ,I wasn't sure if NSBs were ever intended t be used in 3ph boards, I know the NSB blanks don't fit 3ph boards properly (have been forced to use them as short term measure)... but then the NSB blanks are pretty pants all around!

Spark123 · 29 Apr 2009

I don't see why not - you can buy NSB 3 pole MCBs

Adam_151 · 29 Apr 2009

Spark123 said:
I don't see why not - you can buy NSB 3 pole MCBs

Just looked at the wylex catalogue, and seems you can, odd.

I'd been lead to believe that PSB was the tph board rangec

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Short Circuit Capacity

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