Cable Long Runs.Experience,Theroy

[Terry Given]

Mr.T wrote:

"Jasen Betts" <jasen@free.net.nz> wrote in message
news:efd.44245c06.6f8c7@clunker.homenet...

Or would he be better off installing copper pipe (skin effect where
electrons prefer outside of strand to inside)?

skin effect is for AC only.

DC that varies over time has an AC component.

High frequency AC only.

MrT.

thats a common misconception; it applies for all AC, e.g. mHz to GHz

the skin depth in 25C copper at 50Hz is d = 9.34mm. go look at some huge
AC busbars.

This means that for all but the largest transformers, the conductor
thickness is a small fraction of d, so the ac-dc resistance ration Fr ~
1 and both skin and proximity effect can be ignored.

Cheers
Terry

 

[David Sauer]

On Sun, 26 Mar 2006 22:22:41 +1000, Mark Harriss <billy@blartco.co.uk>
wrote:

Mark Hathaway wrote:


Yes I am saying use an inverter to convert 12 volts dc to 240v ac


If the turbine produces a regulated 12 volts, then a 12v dc to 240v ac
inverter, such as the jaycar pn MI5088 1000watt inverter is the ticket. 10
or 15 amp 3 core wiring over 400 meters is no problem at all if done
properly, forget extension leads, use 3 core flex from the electrical shop
with connector boxes, will be cheapest to buy 4 drums of 100 meter flex I
think, but enquire.

If the turbine's output voltage follows rpm, its not going to be so easy. Do
you have any data, pics, etc of the turbine?


Regards,
Mark


What turbine??, the OP's turbine?. Even using 240V flex will lose you
87.9 Volts based on the original poster's power requirements, 14 AWG 15A

Calculations based on what load ?

What were the OP power requirements. They only wanted lights and power
and maybe a TV. This maybe as little as 300 Watts if they are careful
with what is installed.

copper wire and 800M round trip distance, this is 37% power loss. If he
could go as high as say 480V at half the current to 240V the power loss
would be 9% using the same resistance wire.A couple of 240V transformers
wired together could bring it back to a lower voltage suitable for
batteries and an inverter at the far end.

 

[Mark Harriss]

David Sauer wrote:

Calculations based on what load ?

What were the OP power requirements. They only wanted lights and power
and maybe a TV. This maybe as little as 300 Watts if they are careful
with what is installed.

Well, He said 12 volts at 130 Amps = 1560 Watts which I think
is optimistic for a car alternator. 14 AWG is 1.69 Ohms per
100 metres