2391 question

[wrighty]

calculate, using the data below, the earth fault loop impedance of a radial circuit using 1.0mm conductors, for line and cpc, show all calculations.
ze= 0.09
cable length=10m
conductor resistance=18.10mohms/m

struggling with this question and havnt a clue where to find the formula/equation, i dont want the answer just how to work it out cheers

 

[Guest123]

A little hint, Zs = Ze+(R1+R2).

 

[jdd]

'Think' you just need to divide 18.10/1000 then times by cable distance plus Ze.
Should be your Zs.

 

[wrighty]

0.27?????

 

[jdd]

I've got it to 0.271

 

[wrighty]

yeh i got it at that but i get the jist, thanks alot lads, struggling a little with these calculations etc, but only had GN3 a week, n just 5 weeks to go untill my exam, gunna av to really knuckle down n get em cracked off, be eating drinking n sleeping formulas,

 

[jdd]

Haven't got OSG with me, thought that 18.10 was the combined resistance of r1+r2

 

[telectrix]

i got 5.2, but on checking, that's the abv on the bottle i'm supping from at the moment.

 

[wrighty]

trying to read GN3 every day, n minute i put it down i havnt a clue what ive just read, its not good, any revision tips will be greatly appreciated

 

[jdd]

Keep reading GN3 (I'm not being sarchastic.)

 

[Guest123]

I think the 18.10 m/ohms is for one conductor.

I dont have material to hand to check but seem to remember 1.0mm T&E having an R1+R2 of 0.036 odd ohms per metre.

 

[SPARTYKUS]

I got 0.452 Ohms.

I assumed the 0.0181 Ohms/ metre was per conductor, not doubled up?

So

(0.0181 x 2 x 10) + 0.09 = 0.452 Ohms => Zs

 

[jdd]

think you're right mate.

 

[SPARTYKUS]

Ah! beaten by a super mod

 

[wrighty]

0.452 i think is the answer