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 Topic: Cable/Wire sizing AC/DC
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BarkyJ
Senior Member

Joined: 26 April 2018
Location: New Zealand
Online Status: Offline
Posts: 114
 Posted: 11 May 2018 at 10:28am | IP Logged Copy link to clipboard
Hi All

Just doing some planning.
What is typically done for power cable from the windmill to whatever interface you guys use, and do you normally run 3 phase AC down the pole and rectify it at the ground, or rectify it on the windmill and run DC down the pole?

I found a good youtube clip which has an attached excel sheet for doing calculations which is quite useful.

Based on this, my estimation whether I run AC or DC down the pole, I am in the region of requiring AWG 8 cable, which isnt cheap stuff.
My estimation so far is 15m one way, so 30m of cable (assuming DC 2 wire).

Curious what others are using and where you sourced the cable from.

Thanks

BarkyJ
Senior Member

Joined: 26 April 2018
Location: New Zealand
Online Status: Offline
Posts: 114
 Posted: 11 May 2018 at 11:40am | IP Logged Copy link to clipboard
http://www.nzev.co.nz/10mm-flexible-cable/

This is what I am currently looking at.

Warpspeed
Guru

Joined: 09 August 2007
Location: Australia
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Posts: 2164
 Posted: 12 May 2018 at 10:42am | IP Logged Copy link to clipboard
You do not say what your system voltage is, or the expected current.

Ten mm squared cable has a resistance of .00172 ohms per linear meter, so 30m of that cable will have a resistance of .0516 ohms (at 20 Celsius).

The "normal" current rating for 10mm cable is 50 amps.
I squared R gives a power loss of 129 watts at 50 amps for 30m of cable.
Voltage drop at 50 amps would be 2.58 volts.

I have no idea if those are significant figures for your intended application.

__________________
Cheers, Tony.

BarkyJ
Senior Member

Joined: 26 April 2018
Location: New Zealand
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Posts: 114
 Posted: 12 May 2018 at 3:03pm | IP Logged Copy link to clipboard
Sorry the system voltage at this stage is 36V.

Warpspeed
Guru

Joined: 09 August 2007
Location: Australia
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Posts: 2164
 Posted: 12 May 2018 at 4:16pm | IP Logged Copy link to clipboard
So its going to have about 7% loss at 50 amps.

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Cheers, Tony.

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