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Anonymous Poster

cable size

07/31/2010 10:28 AM

i want konw about,cable sizw v/s cable current capicity.
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wareagle
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#1

Re: cable size

07/31/2010 11:13 AM

The bigger the cable, the more current capacity
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kvsridhar
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#2
In reply to #1

Re: cable size

07/31/2010 11:23 AM

i am curious... it says somewhere that "CR4 - the Engineer's Place"

So......how does CR4 ensure that those who ask anything are "engineers" of some sort?

Maybe we can start a thread on this....

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Tornado
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#3

Re: cable size

07/31/2010 11:28 AM

The cable capacity depends on its size, the type of insulation, the ambient temperature; whether the cable is in air, conduit, cable tray, or underground; how many conductors are adjacent, etc. There is no simple formula for this; rather, one looks it up in the local electrical code or in cable manufacturers' literature.

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Hameedullah Ekhlas
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#4

Re: cable size

07/31/2010 11:42 AM

Here it is.
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Anonymous Poster
#5
In reply to #4

Re: cable size

07/31/2010 12:26 PM

Could you please explain what is:

3x16+10 sq mm

What is +10 ?

Thanks for help Leninove.
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Hameedullah Ekhlas
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#6
In reply to #5

Re: cable size

07/31/2010 12:39 PM

3x16 refers to three phases, A,B,C and +10 is for neutral. It is just an insulated cable for underground low voltage distribution system.

It was just an example. Current capacity of each size is not constant. It depends on company's catalog.
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pnaban
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#14
In reply to #6

Re: cable size

08/01/2010 8:49 AM

What is the insulation/sheath materials and who is the manufacturer and country of manufacture?

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portugalphilip
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#7

Re: cable size

07/31/2010 2:19 PM

Cable is a resistor (unless it a superconductor.) so if the cable is very long it has more resistance than a short cable of the same diameter.

Now from the manufacturers data you can apply V=I.R and W=I.V and work out the power dissipated from your cable.

But saying this it is much easier to just overrate the cable size as there will possibly be some problems and an exactly calculated cable will be at it's limit (as calculated.) already and after that if the circuit draws more current but not more enough to trip the safety devices then your cable starts to melt its insulation.

DC is more expensive to transmit over long distances than AC which is why DC is normally for local use.

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Anonymous Poster
#8
In reply to #7

Re: cable size

07/31/2010 4:28 PM

"DC is more expensive to transmit over long distances than AC which is why DC is normally for local use."

Would you please give some more explanation in this part.
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portugalphilip
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#9
In reply to #8

Re: cable size

07/31/2010 6:19 PM

.............Okay.....

Normally dc is a lower voltage when generated and ac is higher voltage when generated.

so cable resistance in the formula V=IR you get less current flowing allowing you to reduce the diameter of the cable.

In europe I think most ac transmission lines are 33 KV or 11 KV and if you wanted to transmit dc at this level I am sure it would cost more.

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garth
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#10
In reply to #9

Re: cable size

07/31/2010 11:38 PM

What you should say is conversion equipment for DC at high voltages compared to ac would be impractical.

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portugalphilip
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#17
In reply to #10

Re: cable size

08/01/2010 4:49 PM

Yeah you might be right....but if it is impractical it is going to be more expensive.

Expression can be complicated sometimes.

Thanks.

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kvsridhar
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#11
In reply to #8

Re: cable size

07/31/2010 11:53 PM

DC transmission exists all over, given certain conditions. Please check out this thread:

http://cr4.globalspec.com/thread/57029

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garth
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#12
In reply to #11

Re: cable size

08/01/2010 4:08 AM

Read my statement I did not say it was not done I said it was impracticable as compared with AC.

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kvsridhar
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#13
In reply to #12

Re: cable size

08/01/2010 5:57 AM

My post was in response to that one by the anonymous guest. Not yours.

And it was not a contradiction of anything said by anyone...just a pointer that this has been discussed in some depth earlier.

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garth
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#15
In reply to #13

Re: cable size

08/01/2010 9:26 AM

Sorry I had my post Nos mixed up

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kvsridhar
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#16
In reply to #15

Re: cable size

08/01/2010 9:30 AM

No problem, i do it all the time ...... no sorry necessary

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PWSlack
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#18

Re: cable size

08/02/2010 12:33 AM

It's all in British Standard 7671. Got a copy?

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JavaHead
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#19

Re: cable size

08/02/2010 10:15 AM

To the OP, here is the best process to find what you seek:

Start here.

Or here.

Get some of this.

Learn how to do this.

We are happy to assist those that make an effort to assist themselves first, but seek further guidance and know how to ask for it.

JavaHead

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Anonymous Poster (2); garth (3); Hameedullah Ekhlas (2); JavaHead (1); kvsridhar (4); pnaban (1); portugalphilip (3); PWSlack (1); Tornado (1); wareagle (1)

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