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Anonymous Poster

selection of HT cable size 11 KV

02/05/2009 10:45 AM

I am planning one project for provision of power supply for RO plant. The requirement of power is 500 KW and I have planned to install 11 KV / 433 volts power distribution transformer of 630 KVA capacity. The distance between existing 11 KV power supply tapping point and proposed location of 630 KVA transformer is 3200 Metre. Kindly suggest the size of 11 KV HT XLPE armoured cable with stranded aluminium conductor.
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2
V.I.Abraham
Guru
Safety - ESD - New Member India - Member - New Member Engineering Fields - Energy Engineering - New Member

Join Date: May 2007
Location: Pune , India
Posts: 875
Good Answers: 42
#1

Re: selection of HT cable size 11 KV

02/05/2009 2:53 PM

Hi Guest ,

It is not correct for you to ask for the size of the cable instead of your calculating it yourself. Standard cable rating charts are available in engineer's hand books. All cable manufacturers provide their own charts which is provided by their distributors.you only have to apply de rating factors depending on your situation and laying conditions. The following conditions may be verified.

There is no fixed formula to calculate the cable size. The calculation of cable will depend on many factors

1. Voltage ( 11 kV in your case)the type of system ( earthed or unearthed system)

2 .The source of supply

3. Total load and distance of load centre from the source.

4. Ambient Temperature

5. Type of cable ( You decided for XLPE)

6 Cable laying method ( OH/ under ground with depth of laying)

Other considerations are given below.

1. Short circuit rating of cable to be chosen

It will depend on power source, transformer capacity ,cable size ,insulation,initial temperature,finial permissible rise of temperature of the cable ( The data will normally be provided by the cable manufacturer)It will also depend on the type of cable PILC/PVC/ XLPE , Earthed or un earthed system etc. Duration of short circuit depending on the protective system and back up protection which are other important point to be considered

2.. Voltage drop

You must check the likely voltage drop for which standard chart is available which should be referred.

3. Power loss.

Power transmission loss in cable should be calculated as per the data provided by the the cable manufacturer.

4. Type of cable laying / depth of cable laying soil conditions etc. and other de rating factors to be considered for the calculation.

After considering the de rating factors and factor of safety you can arrive at the final calculation.
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harish.g
Participant

Join Date: Nov 2009
Posts: 3
#5
In reply to #1

Re: selection of HT cable size 11 KV

11/21/2009 3:54 AM

Good answer.

Can u please suggest me where shall i get the complete data as well as list of all IEC and IS codes.
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SimonMasters
Participant

Join Date: Apr 2012
Posts: 2
#8
In reply to #1

Re: selection of HT cable size 11 KV

04/28/2012 4:22 AM

Agreed the size has to be calculated and this may be a request for assistance with "homework". However sometimes it is necessary for a non-expert to check a suppliers recommendation (because we all know suppliers mark up prices and occasionally over-specify solutions), so I find the "you should not be working with electricity" comment patronising.

If the tables are "readily available" please provide links. Since the question does have an answer it should be possible to provide indicative detail like "70mm2 is the minimum adequate for 1000 metres underground at 500kW". This is my understanding of this user's need for an answer.
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craigza
Power-User
South Africa - Member -

Join Date: Nov 2008
Location: Johannesburg
Posts: 295
Good Answers: 12
#2

Re: selection of HT cable size 11 KV

02/06/2009 12:57 AM

Hi there,

I agree with the answer stated previously. If you do not know how to calculate this - you should not be working with electricity.

99.99% of the time some PE is going to have to sign resposnsibility for this - based on your question you are not this person.

Is this a homework quesiton - sounds like one.

One other thing - the legal requirements will differ from place to place. This will include fault level current; allowable %VD; type of cable; gland requirements; joint allowances etc etc etc.

Most cable manufacturers have booklets refering to the standards for the country they manufacture in - these books will give you examples as well as the de-rating factors to take into consideration based on that countries applicable engineering code.

Try google.

Regards,

Craig
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2
Anonymous Poster
#4
In reply to #2

Re: selection of HT cable size 11 KV

10/07/2009 2:44 AM

U R sick!!! If U can't help or don't have anything useful to say, you'd better keep your mouth shut!!!
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Anonymous Poster
#3

Re: selection of HT cable size 11 KV

07/28/2009 2:43 AM

95mm 11 KV HT XLPE cable would be ideal for the job. It has a current rating of 260A in air and 205A in ground.
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Anonymous Poster
#6

Re: selection of HT cable size 11 KV

10/14/2010 7:35 AM

full load current=kva/rut(3)x11kv=4001.03A

After derating =4001/0.685=5840A

SINGL CORE AU XLPE CABLE 1Rx1Cx800sqmm withstand capacity=1059A

SO FINELY 6Rx1Cx800SQMM/PH AU XLPE CABLE WILL BE SUTABLE
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Anonymous Poster
#7
In reply to #6

Re: selection of HT cable size 11 KV

10/14/2010 7:42 AM

WHAT IS THIS R U ELECTRICAL ENGINEER
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SimonMasters
Participant

Join Date: Apr 2012
Posts: 2
#9

Re: selection of HT cable size 11 KV

04/28/2012 4:23 AM

Did you get an answer? I have the same challenge.
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Users who posted comments:

Anonymous Poster (4); craigza (1); harish.g (1); SimonMasters (2); V.I.Abraham (1)

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