Since every location is a little different, I would suggest testing with a small weather vane and something like fishing line. The characteristics of the changing winds would affect this the same way they would affect a big mill.

Isn't it so cool to put up a mill?

We have indeed discussed this at several points in the past. The old board makes searching very unreliable.

I will try and condense it down for you in this comment. Of course standard disclaimers apply and not everyone agrees on the "perfect" solution.

It sure seems like most of us simply use a pendant cable that is fed down the tube the genny mounts to. Some use a plug / socket arrangement on the end of the cable near the ground that can be disconnected to untwist any kinking in the cable up the tower center. Some folks also use a safety cable between the mill and the tower to limit how many turns it can go in any one direction. You do need enough cable slack for a few turns around the mount so the feed cable which should be stranded cable doesn't become mechanically stressed from the tracking of the mill. I believe that the normal random nature if wind direction changes, etc will tend to wind and unwind the cable in long term use. One mill i have had up for most of a year has not needed either safety cable or unwinding and occasionally it will have one wrap around the tower but eventually it unwraps and all is well [so far]. My mounting does not allow for cable down the tube.

I run my cable well out on the tail boom from the genny and it is held with cable ties from there I run it over to the tower [a pipe] with a longish drooping loop and it is attached with good old duct tape to the tower just below the blade tips. It has enough of a loop to wrap around the tower several times before it could get tight.

The advantages of the pendant cable are its simplicity and low resistance compared to slip rings.

Disadvantages of sliprings are moving parts that wear, brushes and rings that add resistance to the generator [not good] and DIY engineering one is difficult at best. To my knowledge commercial sliprings are not readily available for windmill use.

Hope that helps.

Cheers.

TomW

Ignarus can exsisto rememdium. Sardus est forever

We discussed this at Hughs seminar somewhat...
He likes to run the cable down the center of the mast and let 'er wind up - he said it's rarely ever a problem and if it is, it's easy to unwind by simply unplugging at the bottom of the mast.

I've never heard of anybody havinng problems with a cable damaged or twisted off.

Slip rings on the other hand are resistive, and somewhat complex.  A failure at the slip rings (and I believe they are probably more likely to fail than a solid cable unless very carefully made) would result in total loss of output from the machine, and the machine would be overspeeding - it could result in the total destruction of the wind turbine.

My main mill is a rebuilt commercial one a  compound wound generator so DC output, origionally it had one slip ring, the earth was via the tower. As it gets very dry here I did not include the slipring when I rebuilt it, afraid of sparks, i just used a heavy extension chord hung down through the centre.

This mill winds it's self up regually in good winds. But I believe it is due to trees nearby, the tower is 40 feet, I will raise it to 60 feet which I believe will fix the problem. A 20 foot tower I place my experiments on has a cable and never winds it's self up.

The next old girl waiting to be rebuilt has a servicable slipring, this one I am putting up at 85 feet so it would be nice to get it right. I note comments from Bruce on a seperate post and will have to check the resistance across a cleaned up slip ring and brush.

Once again thanks for the imput it's great not to have to re-invent the wheel.