very low pfc on submain board

[lucus]

hi all hoprfully someone here can answer this question for me: i tested a sub mains today and i only got 0.35 KA is this normal for a submains as at the main mainsboard the pfc is 3.3 KA the main fuseboard has a rcd main switch so at the submain i had to use no trip pfc not sure is this makes and difference any imput would be great.
regards

 

[Sintra]

Did you test Zs at sub main and if so what was this reading.

 

[lucus]

hi
yes zs was 0.36 the submain is fed via a 6mm armoured cable

 

[marcusone]

Hi Lucus

What was your Zs at the sub main ? It will be higher than at the origin so therfore the PFC will be lower.

So as long as all protective devices throughout the installation have a breaking capacity equal to or more than the origin main protective device,then recording the origin PFC is good enough.

Mark

 

[pevvers]

That PFC would be for a Zs at the board at around 0.65 ohms. So not sure where you're going wrong there.... You should be getting a PFC of around 0.68kA if all correct.