pfc test

[nickblake]

it is a good point if you have a substaion very close you could get very low Ze readings and yes very high PSC , having said that the PSC readings can reduce dramatically over quite a short distance this is why we note the PSC and the ratings on MCB's 4ka rewireables 3ka for some of the wylex plug in MCB's 60898's can be 6 or 10ka higher im sure MCCB's then go higher , i may be incorrect as ive been to the first BBQ of the year and a few beer later lol i stand to be corrected if im incorrect

 

[Chr!s]

Perfectly true but only on a single phase 100 A supplies protected by a BS 1361 type II with switchgear to BS 60439-3.

Theres instances where the above wont afford protection. Also spoke to manufactures about guidance given in on site guide and GN3, they have a difference of opinion on the matter.

Cheers. I had a similar problem a week ago. Measured value of <0.01 on firms megger but 0.06 on my fluke. Maybe fluke compensates for low value? I'd like to try your method though. What's your take on PSCC? On the samejob, I measured phase to phase PSCC less than live to neutral PSCC and PEFC Should I have just multiplied PEFC by 2? It will comply regardless as protected by bs88-2

Not necessarily

 

[johnboy6083]

from memory worst case scenrio was 48kA, and BS88-2 breaking capacity was 80kA

 

[Chr!s]

from memory worst case scenrio was 48kA, and BS88-2 breaking capacity was 80kA

Well at 48K, you would need to be careful what you fit downstream.

 

[johnboy6083]

its all 88-2's fortunately

 

[T&Earth]

Hi IQ

Would also be interested in read your R2 method.

Many Thanks

T&E

 

[Guest 004]

Hi IQ

Would also be interested in read your R2 method.

Many Thanks

T&E

the R2 of the trailing lead must be susceptible to fluctuations........

 

[IQ Electrical]

the R2 of the trailing lead must be susceptible to fluctuations........

Well assuming any joints and connections are good, large differences in ambient temperature will always affect an impdance/resistance measurement but a bit of common sense has to be used too!

It's just a way of allowing your meter to work within the range it was designed around.

 

[malcolmsanford]

the R2 of the trailing lead must be susceptible to fluctuations........

The wander lead would be used as a resistance. You would be using the 30 or 50 metres like a resitor to bring the impedance of the test up to a more workable parameter for the tester.................well that is how I would be using it.

Typing as IQ replied sorry.

 

[IQ Electrical]

The wander lead would be used as a resistance. You would be using the 30 or 50 metres like a resitor to bring the impedance of the test up to a more workable parameter for the tester.................well that is how I would be using it.

A perfect description.

 

[Guest 004]

Yes I see your point, never tried it in practice. So you would record the resistance of the lead, then get your readings, then subtract one from another. Very interesting indeed

 

[i=p/u]

seems common sense, i have it all to come tho

 

[IQ Electrical]

Yes I see your point, never tried it in practice. So you would record the resistance of the lead, then get your readings, then subtract one from another. Very interesting indeed

That's almost it but the inserted resistance has to be measured in circuit on the installation to be tested so that it is subjected to the same transformer characteristics.

I'll post the method up in it's entirety and then you can see how simple it really is, I'm muddying the waters now!

 

[Guest 004]

That's almost it but the inserted resistance has to be measured in circuit on the installation to be tested so that it is subjected to the same transformer characteristics.

I'll post the method up in it's entirety and then you can see how simple it really is, I'm muddying the waters now!

I will try it next time, both methods, just to see how good my megger 1552 is!

waiting for the complete article. Thank IQ we are agreed for once !!!lol

 

[IQ Electrical]

I've started a new thread with the simple steps listed:

http://www.electriciansforums.net/i...ccuracy-low-ze-test-procedure.html#post257989