Advertisement - Content continues below
Advertisement - Content continues below

Discuss High PSC in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

S

stedders

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:  American Electrical Advice Forum

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
 
Advertisement - Content continues below
D

DanBrown

  • Thread Starter Thread Starter
  • #2
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??
 
B

biggav22

  • Thread Starter Thread Starter
  • #3
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.
 
K

Kevin

  • Thread Starter Thread Starter
  • #4
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.
 
S

stedders

  • Thread Starter Thread Starter
  • #5
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?
 
Last edited by a moderator:
D

DanBrown

  • Thread Starter Thread Starter
  • #6
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...
 
S

Spudnik

  • Thread Starter Thread Starter
  • #7
Would a trip to the calibraters be worthwhile?

Could be a fault with the unit.
 
S

stedders

  • Thread Starter Thread Starter
  • #8
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
 
Last edited by a moderator:
T

trebor

  • Thread Starter Thread Starter
  • #9
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 ?
 
S

super spark

  • Thread Starter Thread Starter
  • #10
I agree with trebor, sounds like a problem with the instrument.

on a TN-CS the pfc & pscc should be the same.
 
M

murdock

  • Thread Starter Thread Starter
  • #11
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.
 
J

j&selectrical

  • Thread Starter Thread Starter
  • #12
you say 0.9 could you mean 0.09 cheers
 
Aico Carbon Monoxide Detectors
This official sponsor may provide discounts for members
Advertisement - Content continues below

Reply to High PSC in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

Bulk Workwear - Clothing Suppliers for the Whole Forum Network
This official sponsor may provide discounts for members
Advertisement - Content continues below
Top Bottom