PFC Testing

j.capes · Jan 11, 2012

Hi all.

Just a question which seems to get me a bit confused about PFC testing. I understand that the value of PFC you put on a EIC or any other form is the highest value of either the PSCC or the PEFC. Now when you get the reading on your meter (which is sometimes displayed with the Zs value) which one is this? Has the meter automatically worked out the highest value between the two or only given you one? When you plug in the 13 amp adapter into the wall to test Zs is the PFC reading the highest of both the PSCC and PEFC? I understand that all meters operate differently, however how are you able to differentiate between the two tests ?

Thanks for reading and I hope you can help me out !!!!

jjnr78 · Jan 11, 2012

I may have missed something, but your PFC etc will be in amps and the Zs or impedance will be in ohms. The Megger tester I use has a different function for both. I'm assuming whatever you use combines both values. For PFC and depending on the earthing system i test line/ earth and line/ neutral recording the highest value as PFC.

malcolmsanford · Jan 11, 2012

As far as I'm aware it is taking both readings and displaying the highest, it does with Martindale testers anyway.

jjnr78 a lot of the MFTs now when doing the Zs live test will give you the main display of the earth fault loop impedance in ohms and in the bottom r/h corner will be a smaller read out of the PSCC in amps normally, not Ka

j.capes · Jan 11, 2012

Thanks for your replays. Would have thought they would display the two different values for PSCC and PEFC? I suppose only way to find out would be to read the manual for whatever meter you were using! Thank you both for your help.

Deleted member 26818 · Jan 11, 2012

PEFC, is calculated using the voltage and the impedance (Z1 + Z2) of the Line and CPC.
PSCC, is calculated using the voltage and the impedance (Z1 + Zn) of the Line and Neutral.
Unless your tester conducts both tests at the same time, or has a funtion where it will remember the value for one test, when you conduct the next, you will have to remember the value yourself, and compare it against the value for the second test conducted.

j.capes · Jan 11, 2012

So to measure the PFC at the origin of the supply, this would consist of the two tests you've mentioned above? I can understand with a two lead tester but what about a three lead test machine?

Deleted member 26818 · Jan 11, 2012

j.capes said:
So to measure the PFC at the origin of the supply, this would consist of the two tests you've mentioned above? I can understand with a two lead tester but what about a three lead test machine?

My tester (Metrel 3000i) uses 3 leads, but different positions on the selector.
I conduct the PSCC test, switch the selector, conduct the PEFC test, record the highest value, then disconnect the earth conductor and conduct the Ze test.
My tester may well have the facility to remember the two values, and even display the highest.
I haven't noticed it, or bothered looking for the function, as remembering the value for the time between tests is not something I have a problem with.
You ever hear someone muttering to themselves 0.39, 0.39, 0.39....., that's probably me conducting the tests.

gtownspark · Jan 14, 2012

I use a Fluke 1651 with 3 leads, when using this tester you need to connect all the leads to carry out a Ze P-E on Loop setting, the value displayed at the bottom is the PEFC. You then need to change the setting to P-N still on Loop to measure the PSCC. The highest reading is your PFC. So it seems the answer to your question is, it depends on your tester.

DNO · Jan 15, 2012

you are talking about 3 different checks I feel here.
1=Ze ie earth loop impedance, 3 lead if sep earth, 2 lead if pme.
2=PEFC ie 2 lead line + neutral
3=PSCC ie 2 lead line+neutral

Deleted member 26818 · Jan 15, 2012

Do you mean:
2=PEFC ie 2 lead line + neutral,
or
2=PEFC ie 2 lead line + earth?

GB266 · Oct 23, 2012

spinlondon said:
My tester (Metrel 3000i) uses 3 leads, but different positions on the selector.
I conduct the PSCC test, switch the selector, conduct the PEFC test, record the highest value, then disconnect the earth conductor and conduct the Ze test.
My tester may well have the facility to remember the two values, and even display the highest.
I haven't noticed it, or bothered looking for the function, as remembering the value for the time between tests is not something I have a problem with.
You ever hear someone muttering to themselves 0.39, 0.39, 0.39....., that's probably me conducting the tests.

Thanks Spinlondon. This makes it clear for me as I find Metrel manual very confusing on this part of testing!