Regs Help Please!

[notrutsa]

Hi all, can anyone help please?
I'm currently studying for my 2382 and am completely stumped!
Does anyone know where I can find in the BS7671 what the value of the multiplier is to apply to R1+R2 to allow for temperature rise under fault conditions?
Thanks, Andy

 

[mars6394]

not sure if this is what u are looking for ZS=ZE + r1+r2
1000

 

[Des 56]

Do you mean the maximum zs allowing for temperature rise


Tables 41.2 41.3 41.4 give the max zs for devices
On site guide page 100 will give a divisor of 1.24 for temp rise to apply to the max figures for cables at 10 degrees,these max permitted are lower than in Bs 7671

Use 80% values for the ones in the bs7671

 

[Guest123]

Maybe appendix 9 in the OSG.....these are the factors you use to correct the resistance calculation of cables in table 9A, for temperatures other than 20 degrees C.

 

[saveloy]

Maybe Appendix 14 page 361 BRB ??

 

[Guest123]

Maybe Appendix 14 page 361 BRB ??

I think that'll pretty much be what he's after....as R1+R2 is concerned with loop impedance too.

 

[ezzzekiel]

Do you mean the maximum zs allowing for temperature rise


Tables 41.2 41.3 41.4 give the max zs for devices
On site guide page 100 will give a divisor of 1.24 for temp rise to apply to the max figures for cables at 10 degrees,these max permitted are lower than in Bs 7671

Use 80% values for the ones in the bs7671

my opinion too

 

[Steve D]

I thought he's talking about temp rise arising from fault conditions.

Isn't the 0.8 rule of thumb in Appx 14 used to take into consideration the temperature of the cables under 'normal/loaded operating conditions' as oppsed to fault conditions ?

 

[notrutsa]

Thanks for all your replies, but none of these appear to relate to a temperature rise in fault conditions, rather than ambient temperature correction factors for cable size calculation (table 9B on P167 of the OSG) or the correction factor for the material of the insulation (table 9C on P168 of the OSG).
Any other suggestions?
Thanks,

 

[Steve D]

Can you type in the exact wording of the question you are taking this from please ?

Cheers
Steve

 

[notrutsa]

Can you type in the exact wording of the question you are taking this from please ?

Cheers
Steve

It is pretty much as stated in my first post; "State the value of the multiplier to be applied to (R1 + R2) to allow for temperature rise under fault conditions."
Thanks.
Andy

 

[Steve D]

I found this on the voltimum site the following:

"This will depend on the cable insulation For thermoplastic (70 oC PVC)it is 1.2 for thermosetting (90 oC XLPE) it is 1.28 There is useful information in IEE Guidance Note 3 In annexe B which may also be useful information for you to read "

I haven't got my guidance notes to hand. Although it doesn't say where to find the info in the regs book. Strictly, all the answers to sample 2382 questions should be able to be sourced from the regs book.

Cheers
Steve

 

[Risteard]

I would go for 1.2

Multiply (R1+R2) by 1.2 and add this to the Ze, and then compare this value with the maximum Zs permitted by the Regulations. However that is for conductor operating temperature.

 

[notrutsa]

I found this on the voltimum site the following:

"This will depend on the cable insulation For thermoplastic (70 oC PVC)it is 1.2 for thermosetting (90 oC XLPE) it is 1.28 There is useful information in IEE Guidance Note 3 In annexe B which may also be useful information for you to read "

I haven't got my guidance notes to hand. Although it doesn't say where to find the info in the regs book. Strictly, all the answers to sample 2382 questions should be able to be sourced from the regs book.

Cheers
Steve

Thanks for your help.
Andy