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Participant

Join Date: Sep 2008
Posts: 3

Cables Size

09/24/2008 11:41 AM

Can you let me know the cable size for

  • XLPE/SWA/LS/PVC
  • 11 kV
  • load to serve 5MVA
  • 1000 meters
  • 3-core
  • To be laid in underground normal soil
  • Also to be laid in PVC conduits.
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Guru
United States - Member - New Member

Join Date: Jun 2008
Location: Alabama
Posts: 1604
Good Answers: 63
#1

Re: Cables Size

09/24/2008 7:48 PM

Why don't you try to make the calculations your self and we will assist you.

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Anonymous Poster
#2

Re: Cables Size

09/25/2008 2:37 AM

use HT cable 4C x 250 sqmm,

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Participant

Join Date: Sep 2008
Posts: 3
#3
In reply to #2

Re: Cables Size

09/25/2008 4:08 AM

i have forget the formula to calculate, can you help by sending the formula for the calc

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Commentator
Engineering Fields - Power Engineering - Projects Engineer

Join Date: Aug 2008
Location: Tanzania- East Africa
Posts: 71
#4

Re: Cables Size

09/25/2008 9:49 AM

lenght of cable x VD in Ma X full load amperes . Devide by 1000 you will get the VD

maximum VD allowable is 4 % of the system voltage as per IEE regulations

You will need a cable capacity and Vd chart to calculate the above ,as the installation conditions ,operating temp. and type of cable are all considering factors

Please do this home work and then you will be guided,from where you have reached.

Regards

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Guru
United States - Member - New Member

Join Date: Jun 2008
Location: Alabama
Posts: 1604
Good Answers: 63
#5
In reply to #4

Re: Cables Size

09/25/2008 10:30 AM

''length of cable x VD in Ma X full load amperes . Divide by 1000 you will get the VD"

Sak

I don't understand you formula. I am used to seeing

VD = amps x cable Z per 1000 ft x length /1000

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Anonymous Poster
#6
In reply to #5

Re: Cables Size

09/25/2008 8:46 PM

$$$$ = current multiply hrs multiply rate/hrs divide 1000

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Guru
United States - Member - New Member

Join Date: Jun 2008
Location: Alabama
Posts: 1604
Good Answers: 63
#7
In reply to #6

Re: Cables Size

09/25/2008 9:52 PM

"$$$$ = current multiply hrs multiply rate/hrs divide 1000"

WHAT?

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Commentator
Engineering Fields - Power Engineering - Projects Engineer

Join Date: Aug 2008
Location: Tanzania- East Africa
Posts: 71
#8
In reply to #5

Re: Cables Size

09/27/2008 1:41 AM

Wareangle

you have raised a very good question

Thats the formula we use when we have a IEE current capacity and VD chart at hand,to get the results directly from the pre-calculated chart.

We can know the Volt drop per amp per meter in mv for a given size of cable from the chart multiply by the I and total lenght of cable run than divide by 1000 to convert the result to Volts

Hope that is clear

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