Paul,
>First thoughts: Steel is stronger than aluminum, but it's also much heavier. You
>might get away with greater spacing between poles/towers, but would they need to be
>stringer to support the extra weight?

I thought so too. Then I asked the guy next to me who is running the CAD and stress analysis softvare to make a thin (1 mm plate) round pole and hang 125m of 25mm2 steel wire on each side. To my suprise, the load was nearly nothing. The big load must come from the wind.

Belgian,
>Wouldn't 40 kV be more prone to arching and
>therefore push up the price of the isolation material used?

Yes. I'm counting on the extra cost to be small. I could be wrong.

Trumpy,
>It's a good idea in theory.

Thanks!

>Most aluminium power-lines already have a steel core, running through thier centre.

Yup.

>The further the poles are apart, the higher
>the strain on the poles gets and also you
>need to take into account wind drag,
>thermal effects, etc.

>At 40kV, you'd need pretty big insulators

Any idea how big?

>and the lines would need to be well spaced,
>probably with a double cross-arm arrangement.

SWER = Single wire... [Linked Image]

>We are talking a huge pole for this type of installation!

Please explain why? I definitely need a high and strong pole to go these long distances. But huge?

[This message has been edited by C-H (edited 05-13-2003).]