Question regarding PFC on a sub board.

[nazoom]

Hi

I am trying to carry out Prospective fault Current (PFC) test on a sub board that that is RCD protected and is fed by a main board. My question is how to carry out this PFC (short circuit or earth fault) on the sub board? Do we put the Main switch off in the main board and place the line lead at the line point of RCD that is feeding the sub circuits and then the neutral lead goes on the neutral point of the RCD?

Many Thanks

 

[SirKit Breaker]

Why? If your PFC/PSSC is in spec for the protective device at the origin, it has to be in spec further down the line assuming that your protective devices in sub board are the same kA ratings as the main board, ohms law. Just calculate it if you really want to record it.

Cheers.............Howard

 

[nazoom]

So does that mean that the PSSC/PFC is the same for both the main board and the sub board? And is measured at the Main board?

Thanks.

 

[Jurasic Spark]

So does that mean that the PSSC/PFC is the same for both the main board and the sub board? And is measured at the Main board?

Thanks.

As stated by Sirkit, its down to Ohms Law. The more ohms between you and the source of supply the less Amps you'll have....SIMPLES

 

[nazoom]

But how do i measure PFC/PSSC on the sub board with out calculation?

Thanks again.

 

[telectrix]

the same as if you were doing it at the main board. switch the sub board main switch off with the feed from the main board still on. then measure from the incoming L to N, and L to E at the sub main.