pscc pfc values

[timbobelfast]

You mean PEFC?

PFC is the higher of PSSC and PEFC.

Was it a TN-S?

As TN-C-S should roughly be the same...

 

[trebor]

I have had this result also on a db , 3 from origin, after a bit of head scratching we decided it was parallel earth pats connected to to DB3 which were at a lower impedance at that point than origin due to the length of the sub mains, as we moved back to origin the pscc became the higer value

Also on TN-C-S pscc on line to neutral and pefc are much the same unless you isolate the installation and disconnect the earthing conductor, there is little point in this however as the whole idea is to know the worse case value

 

[telectrix]

sounds as though the previous guy may have read the phase/phase value then doubled it.

 

[Farmelectrics]

tim its a tns system and yes i ment my pefc was higher than pscc on a 3 phase board

 

[ackbarthestar]

tim its a tns system and yes i ment my pefc was higher than pscc on a 3 phase board

That would be Phase to neutral = psc and Phase to earth = pfc ?

If so, then your earthing system from the DB is running parallel back to the main intake. Very low R2 value.

You could try an R2 measurement with a R1 (L1,L2,L3) at the DB then add that to the probable Ze at the main board, if possible. Compare the measured values with the calculated values. Allow 30% for maximum operating uncertainties with the measured values.

Its not so uncommon.

 

[Guest55]

Network fluctuations.
I wouldnt get too bogged down with the finer details of this test personally , its beyond the control of the consumer.
I've had some weird readings before on big installations , usually due to the DNO's supply transformer being on or very close to the site in question.