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Anonymous Poster

Replacing Cables

07/05/2010 1:55 AM

Hi All, We have an existing system where we have 12 runs (4 runs / phase) of 11KV 1C x 630sqmm Al. cables laid between the source and the load. We are in the process of replacing these with copper cables of same size but 6 runs (2 runs / phase). Is 6 runs sufficient or should we go for 9 runs (3 runs / phase)?
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ikhanuk
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Join Date: Aug 2009
Posts: 91
#1

Re: Replacing Cables

07/05/2010 3:12 AM

Dear it depends on the conditions like temp depth cable formation then finally if the cable rating is safe for this option go ahead .

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Hameedullah Ekhlas
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#2

Re: Replacing Cables

07/05/2010 5:39 AM

Engineering is based on calculation not on assumption. So, do calculation and judge.
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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

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#3

Re: Replacing Cables

07/05/2010 11:17 AM

→ British Standard 7671.

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Anonymous Poster
#4
In reply to #3

Re: Replacing Cables

07/06/2010 2:45 AM

PWSlack, Is British Standard 7671 used through out Europe and if not where would I find the european country specific equivalents. It seems that everyone always quotes BS7671 but I never see the one for Luxemburg or Denmark being quoted. Thanks in advance for you assistance.

Thomaz
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LAA_Lucke
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Join Date: Feb 2010
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#5
In reply to #4

Re: Replacing Cables

07/07/2010 4:33 AM

You should check the Cable ratings for copper and aluminium and compare or calculate the amp load with the cable rating tables.

IF the previous Aluminium cables were satisfactory, why do you want to change them?

As a rule of thumb, Copper has 1/2 the resistance coefficient than Alu. Therefore, the 2 run per phase should do. BUT IF the CHANGE is required because of not being satisfied with the ALU cables (were heating etc), then 3 runs will sort your problem out.

Still, re-work the calculation and use the cable rating tables from the cable maker.
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BB Raina
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Join Date: Jun 2010
Posts: 75
#6

Re: Replacing Cables

07/07/2010 8:08 AM

Hi!

Please furnish the details of load and laying of cables. How you propose to lay the cable.

BB Raina
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user-deleted-15
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Join Date: Jun 2010
Location: chennai
Posts: 8
#7

Re: Replacing Cables

07/08/2010 1:06 AM

ADOPT THE RELEVENT STANDARDS and apply the de-rating factor and you can arrive at the solution

Generally copper cable can carry 1000 Amps/Inch.Square and aluminium Cable can carry 625 Amps/Inch.Square (One Inch Square is equal to 645 Sq. MM) and arrive at the cable cross section required and choose the requirement. Then the relevent DE-RATING FACTOR TO BE APPLIED ON THIS VALUE and increase the cable size or run.

This excercise should solve your doubt and problem

sdr710
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Anonymous Poster (1); BB Raina (1); Hameedullah Ekhlas (1); ikhanuk (1); LAA_Lucke (1); PWSlack (1); user-deleted-15 (1)

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