Ze and pfc test on 3 phase board.

[Robo]

Please can someone clarify this please.

I test all three phases on (LE) setting giving me 3 ze readings and 3 pefc readings. I then test all three phases on (LN) setting giving me 3 ze readings and 3 pscc readings.

Record the highest reading of the 6 ze readings.

Then take the highest reading of all 6 pfc readings and double it. Or do you only double the pscc reading?? I've searched the answer and not found a clear verdict.



Also when doing zs readings on outgoing circuits is it better to have my fluke 1651 set to LN or LE. I do the later, however this is somewhat more time consuming??

Any clarification wold be appreciated

 

[Sintra]

Please can someone clarify this please.

I test all three phases on (LE) setting giving me 3 ze readings (this is all you need for Ze the highest of the 3 is recorded) and 3 pefc readings. I then test all three phases on (LN) setting giving me 3 ze readings (not required)and 3 pscc readings.

Record the highest reading of the 6 ze readings.(You will only have 3 as you don't do L-N)

Then take the highest reading of all 6 pfc readings and double it.(correct) Or do you only double the pscc reading?? I've searched the answer and not found a clear verdict.



Also when doing zs readings on outgoing circuits is it better to have my fluke 1651 set to LN or LE. I do the later, however this is somewhat more time consuming??

Any clarification wold be appreciated

In bold above

 

[plugsandsparks]

Ze, Zdb and Zs are all earth loop readings used to establish that the resistance is sufficiently small to operate the breaker / fuse in the correct time. Some testers can do line to line testing to get PSCC, otherwise LNx2 as LN is usually higher than LE.
Not sure why you are testing loop through neutral, i only do this if i cannot get a reading on LE to make sure tester has not lost the plot.

 

[Scornio]

Hi Robo,

you have confused me a tad...but the highest of your pefc and pscc will be you pfc this is the figure you double.

 

[Robo]

So to clarify, test earth loop as normal on LE setting. And double PFC reading. CheersCheers

 

[Risteard]

On a three-phase installation the PSCC will always be greater than the PEFC. If the PSCC cannot be measured directly between phases then double the highest line-neutral short circuit current.

 

[brucelee]

Ze disconnect the earthing conductor then test if you have permission to isolate with earth fault loop setting of your tester set on High loop if no RCD upstream
L1-E
L2-E
L3-E
then reconnect the earthing conductor
then set your test instrument to PFC test high
no need to test PEFC between
L1-E
L2-E
L3-E
you dont need to do this as the the PSCC will always be higher on a 3 phase board
so jsut test PSCC
Eg
L1-N = 3.0kA
L2-N = 3.1kA multiply by 2 and thi is your pfc as this is the highest =6.2kA
L3-N = 3.0kA

reason we multiply by 2 is the PFC will always be igher between the lines and as your not supposed to measure between the lines as not all testers can do this we multiply by 2 which errs on the side of safety
really its more ike 1.732 which is the Sq root of 3 so by multiply by 2 if your protective devices can carry 6.2kA then they comply Icn and Ics