2394 past paper scenario need help please anyone.

[Guest154]

i could type it all out and go on forever , so anyone that thinks i am mixed up or talkin crap just go to page 121 of GN3 table B3, the new edition

 

[NickD]

"Table B3 gives the multipliers to be applied...for the purposes of calculating the resistance at maximum operating temperature of the line conductors and/or CPC". It's just the standard 1.2 tabulated within a table, mate.

Got me out of bed to find my GN3 for that as well...

 

[Guest154]

so why would this multiplier not be used in the formula

 

[NickD]

I haven't followed the nitpicking detail of the thread but I assume you mean for question "B) determine the expected results for each stage". It is asking what resistance measurements you are expecting to get for r1, rn, r2 (in test 1), (r1+rn)/4 (in test 2), (r1+r2)/4 (in test 3). I.e. what are you expecting your meter to show when you test it at ambient temperature.

It is not asking you to then predict what those values would be up at maximum conductor operating temperature so that you could attempt to confirm your Zs is low enough under all operating circumstances. This is not meant to be patronising, just really effing important: it is vital to read and digest the question. Giving the right answer to the wrong question is as bad as giving the wrong answer to the right question.

(In any case you would need to apply your correction factor to your total value of Zs, not just the R1+R2 for the circuit because you have to allow for the conductors in the DNO supply being up at max operating temperature as well. So you'd calculate 1.2x(Ze+(R1+R2)) - not Ze+1.2*(R1+R2). But this is off the point because it is NOT what you are being asked to calculate.)

But then I could be wrong as I'm still waiting for the pass/fail result from my 2394 written! - any day now hopefully. You do know the exam format has changed from the old 2391, which is why the exam is now shorter? I didn't until I opened my actual 2394 paper, and promptly messed my pants.

 

[Guest154]

i just read the question again and i suppose u r right , it was the way i was taught on my 2394 course the lecturer told us always add a multiplier for the cable when it tells u its thermoplastic or thermosetting cable used , so anyone reading this best to ignore my earlier posts and ask the lecturer that is teaching u .

 

[Guest154]

ps a may b wrong again but i dont think ur ze formula is correct u dont multiply ze by 1.2