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guy wire elevation
By oregon wind, Section Wind Posted on Thu Jul 17th, 2008 at 04:03:23 PM MST
guy wire elevation

I am installing a turbine on a hill. I will be using 4 guy wires. Unfortunately my guy wires will all be at different elevations. The two guy wires on the sides that support the pole while raising and lowering are about six feet in elevation different.
any suggestions on what I should do?

guy wire elevation | 10 comments (10 topical, 0 editorial)

Re: guy wire elevation (3.00 / 0) (#1)
by SparWeb (sparweb at ANTISPAM_hotmail_com) on Thu Jul 17th, 2008 at 10:24:03 AM MST
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How much progress has been made so far? Stakes in the ground, or you've already poured all the concrete? Is this a tilt-up? Any more info or pictures you can offer will help me out here.

If you're still staking it out, can you rotate the whole system on the hill?

If it's all built, you may need a mechanism to dis-connect the short guy wire and/or put in a 6-foot extension for the period of time you raise/lower the tower.

Here to help, but I don't know enough about your problem to tell you much, yet.

Steven Fahey

Re: guy wire elevation (3.00 / 0) (#4)
by oregon wind on Sat Jul 19th, 2008 at 10:20:28 PM MST
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Thank you for your response.

I took some pictures, but I can't seem to follow the instructions for getting them on this posting. Sorry not too computer literate.

The tower is a tilt up tower.

The tower is 45 feet tall

The radius of the guy wires is 30 feet

the top guy wire is attached to the tower at 36 feet

The two side anchors that support the tower as it is raised and lowered are at different elevations.

The first of the two side anchors at 30 feet away is 1-2 feet in elevation higher than the tower base

The second of the two side anchors at 30 feet away from tower is 7-8 feet lower than the tower base

The tower tilts up hill slightly, that anchor point is 1-2 feet higher than the tower base

the gin pole side anchor is 7-8 lower than the tower base at 30 feet.

Any suggestions on how I can tilt the tower down without the elevation change causing problems?

None of the anchor points have been set in concrete. However the tower base has been set in concrete.

Thanks

[ Parent ]

Re: guy wire elevation (3.00 / 0) (#5)
by TomW on Sun Jul 20th, 2008 at 12:36:27 AM MST
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OW;

Your photos are over here:

http://www.otherpower.com/images/scimages/10252/P7190277.JPG

http://www.otherpower.com/images/scimages/10252/tower.jpg

Tom

"Education consists mainly of what we have unlearned."--Mark Twain
[ Parent ]

Re: guy wire elevation (3.00 / 0) (#2)
by wpowokal on Thu Jul 17th, 2008 at 06:16:35 PM MST
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The only relevent point is that you have a line of site from each side guy wire through the tower piviot point. I use a lazer level to achieve this.

The tower is lowered up-hill.

allan down under
A life lived in fear is a life half lived.

Re: guy wire elevation (3.00 / 0) (#3)
by Ungrounded Lightning Rod on Thu Jul 17th, 2008 at 07:34:39 PM MST
(User Info)

To clarify:

The line between the points where the two side guy wires connect to their anchors should go straight through the axis of the hinge pin at the base of the tower.

If it goes more than a little above the hinge the guy wires will loosen up as you raise the mill and tighten as you lower it. That means if you tighten the guy wires with the mast up they can snap when you lower it, shoving the mast violently to one side and causing all sorts of havoc.

If it goes more than a little below the hinge, it means the guys will loosen as you lower the mast and tighten as you raise it. That makes for a controlability and hinge stress issue when the mast is coming down. It also makes for a potential snap-the-guy-wire issue when the mast is going up, though you can avoid that by leaving enough slack in the side guys that they aren't overtight when the mast reaches vertical.

The mast WILL rotate along the line between the guy anchors. (Note that this may sweep a cone, rather than a disk, if the line is not horizontal, resulting in the mast lying at an angle other than 90 degrees from the hinge axis when it's down.) If the hinge pin isn't parallel to that you'll put an enormous amount of stress on it - possibly breaking it and dropping the mast in an uncontrolled fashion.

So if you've already put in your anchors, the thing to do is modify the mast mounting so the hinge pin axis and the two side anchor guy attachment points are colinear, or really close to it. Then you're fine.

[ Parent ]

Re: guy wire elevation (3.00 / 0) (#6)
by SparWeb (sparweb at ANTISPAM_hotmail_com) on Mon Jul 21st, 2008 at 01:15:33 PM MST
(User Info)

I suppose I could tease you for getting so far without thinking of that :)

I'll start with my experience and you tell me if it helps. My own tower doesn't have perfect anchor points, either (though much easier than yours). I have to completely slacken one of the side guy wire sets before lowering the tower. Since I wouldn't lower the tower on a day with wind more than a light breeze, this isn't a problem.

You have a much more drastic situation to cope with, and there may be a couple of things you can do. Firstly, an anchor point that is very low makes the guy wire extra long. When the tower is lowered, that wire is very loose. When lowered it gets very slack, which isn't bad, except for you it's slack by a lot when the tower is down. Maybe that will help, in fact, if the lay of the wire on the ground has to follow a hill, then maybe you need the extra slack.

A cable that is "too long" when the tower is lowered can be "shortened" by moving the anchor point away from 90 degrees, too. If it's moved farther from the tower's lowered position, the slack is taken up again as it's lowered. This is a great idea in theory, but it's quite hard to do in practice, because of the hill that got you in this mess to begin with.

The opposite is true for the other anchor point. When it's higher than the hinge, it tightens as the tower is lowered. A real problem, and when you have to slacken it by a couple feet, then you need to be able to disconnect the wire for the purpose of lowering. The mechanism must be safe and reliable so it won't open when the tower is in use.

Gotta go now, I'll be back with more thoughts later on.
Steven Fahey

Re: guy wire elevation (3.00 / 0) (#7)
by SparWeb (sparweb at ANTISPAM_hotmail_com) on Mon Jul 21st, 2008 at 10:34:48 PM MST
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Okay, I'm back (postus interruptus).

I want to add a few questions:
Can you dig out part of the hill to even out the guy wire point that's too high?
Do you need to cement in anchors or do you have soil that requires or allows alternatives?
How close is the tower to the house? What size of windmill will you install?

I also wanted to say that your hinged base looks fantastic. Are those city lamppost or overpass signpost standards? Apart from being heavy, the tower is probably very rigid.
Steven Fahey

Re: guy wire elevation (3.00 / 0) (#8)
by oregon wind on Thu Jul 24th, 2008 at 07:28:06 PM MST
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Hey Steven:

Thanks for the hinge compliment! This is a 45' street lamp tower. I managed to purchase two of them. They are quite stout, and have a base that was nicely adaptable to hinging.

In answer to your questions.

I can dig out part of the hill that is too high and that is my plan.

I will be installing cement anchors. I had some custom auger anchors made that are 6 feet long with two ten inch augers on them. Unfortunately, I went to install them and hit rock, my tractor twisted the top off a 7/8" diameter auger.

The tower is 75 feet from my house and barn

I will be installing a 13' wind mill, but I am building this tower to hold something larger should I ever decide to install one.

I will also be installing a second wind mill with the same problems with elevation shortly after this one, so that I may test different windmills in the same wind.

I think my solution will be as follows . . .

I have figured the angle of the cable coming off of the tower down to the ground. I will drill 30" diameter holes 5' deep at the point in the ground that the cable would hit using the angle from the top of the tower. (The cable down hill will be much longer). I will then install a steel pole (probably 4-6" diameter) set in concrete, at the 30' radius that is high enough to meet the elevation of the bottom of the tower. I will either have a large eye on the top of this pole and send the cable through it, or I will attach the tower to the eye, then from the eye to the anchor in the ground.

The eye on the top of the tower will act as the pivot point for the long cable, making it so that it doesn't get loose when lowering the tower.

I hope I explained this well enough to understand.

Let me know if you agree, and thanks for your time.

[ Parent ]

Re: guy wire elevation (3.00 / 0) (#9)
by SparWeb (sparweb at ANTISPAM_hotmail_com) on Fri Jul 25th, 2008 at 12:57:29 PM MST
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"...my tractor twisted the top off a 7/8" diameter auger..." OUCH!

By that comment alone, I expect your tractor is big enough to pull the tower up.

I think I kept up with the explanation, except I don't picture what would pivot at the top of the tower.

Anyway, if what you describe is an anchor pole that rises 6 feet out of the ground to make the guy line work, then you're okay. You're going to cement it deep in the ground, so pulling on the top of the pole is possible without prying it out of the ground.

With a 45' tower and a 13' mill, your guys attach somewhere around the 36' mark. Even though the pole is thick, the windmill is big. If you don't put a set of guys at the 18' point (halfway up), the pole may dance around a bit in the middle. Those middle wires don't have to be very heavy to do their job.
Steven Fahey
[ Parent ]

Re: guy wire elevation (3.00 / 0) (#10)
by oregon wind on Sat Jul 26th, 2008 at 07:09:12 PM MST
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I agree. I do have ears on the tower to put cables on the 36' mark and right around the 18' mark.

Yes, I will be putting the anchor pole deep into the ground with cement. Do you think this is my best option?

Thanks for your time.

OW

[ Parent ]

guy wire elevation | 10 comments (10 topical, 0 editorial)

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