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stedders

Hi have tested a PME installation and am getting a reading of greater than 10KA on the psc, using a fluke 1652 all other readings are fine and within limits etc, does any one know what this could be?
I am guessing it is a fault on the distribution side was going to recommend telling the local board.

Many thanks
 
The more the better you could say and doesn't exactly mean a fault.. What reading are you getting?
It could just mean that you have a very good earth and a low impedance I.e. Good Ze.

What is your Ze??
and what is the current reading??
 
not a fault probably very close to supply transformer. all you need to do is check that any protective device is capable of breaking the fault current. if at has mcbs check they have a rating above 10KA. normally displayed on mcb as 10M. if fuse bs 88 will be fine anything else might need changing.
 
Thats intersting stedders, I have a Fluke 1652 as well, and got a 10kA PFC today as well (PEFC was just over 1kA, but PSSC was 10kA), Ze was 0.23, not sure if this is a fault with the 1652, as I have had this a few times recently.
 
The Ze was 0.9 and the PFC 2.7KA which all works out correct.
But this was PSC and the reading came back at >10KA fluke only goes up to 10KA.
This high PSC would blow the wylex 3036 fuses apart if there was a be a fault between L & N, they only have a breaking capacity of 3K (would blow apart all domestic MCB's)

Thanks for the reply's I know the people opposite I could check the PSC there and see if they to have a high reading?
 
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The Ze was 0.9 and the PFC 2.7KA which all works out correct.
But this was PSC and the reading came back at >10KA fluke only goes up to 10KA.
This high PSC would blow the wylex 3036 fuses apart if there was a be a fault between L & N, they only have a breaking capacity of 3K (would blow apart all domestic MCB's)

With a Ze of 0.9, How do you get 10Ka Fault current.. I work it out to be in the region of 256 Amps.. and is about right. 10kA seems amazingly high, and ive never come across such a high reading as this. I use the same tester as you, fluke 1653...
 
yep could be tester but is still within time frame since last calibrated.
I might be missing a trick here but the Ze measurement is irrelevant because the PSC where my high reading is, is testing down the Live and Neutral not the live and earth which would be the PFC which is OK at 2.7KA.

But this is a PME (TNC-S) so readings should be close?? because using same cable in theory.
Well so I thought? if you can tell me different please do

small mistake in earlier comment Ze was 0.09 not 0.9. But still does not explain the >10KA on PSC
 
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Hi have tested a PME installation and am getting a reading of greater than 10KA on the psc, using a fluke 1652 all other readings are fine and within limits etc, does any one know what this could be?
I am guessing it is a fault on the distribution side was going to recommend telling the local board.

Many thanks

if its a pme service and you are getting 10ka on pscc and pefc settings as its a pen conductor these must be the same, the Ze should be around 0.023 -0.025 depending on the actual voltage and the length of earthing condutor, must be a problem with the instruments processor I would think ?
 
i am having a similar problem with a 1653...i cannot understand why the instrument keeps going >2000 ohms and >50 ka ...we did calculation and worked out that it should read 17.6 ka and 0.01 ohms...beacuse the restance is so low you would need a 3 digit after the decimal point but the instrument will read 13 ka and 0.01 ohms on 2 of the circuits we tested but out of range on all the other circuits.

the test is being carried out 150 metres away from a 1000 kva transformer at the main distribution panel...which is fed by 3 x 300 mm ecc cables and a 1600 amp main switch...the tests are being carried out on the circuit breakers in this panel.

the reason we decided to go to the main panel was because we were getting higher readings on one phase than the other 2 phases in a panel further away from the main panel...0.4...0.4 and 1.2 ohms on the blue phase...which normally indicates there is a bad connection in the system further upstream.

we did the tests at the main panel with a megger loop tester and the readings seemed fine.

by the way the system is tn-s


any help would be appreciated.
 

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