Author Topic: Planning my next Wind turbine  (Read 1444 times)

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Shadow

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Planning my next Wind turbine
« on: November 20, 2005, 11:42:29 PM »
 My current turbine is dual rotor 2x1x1/2 inch neos, 12 pole 9 coil 140 turns of 17 ga.wired in star for 48 volt at 152 rpm cut in. 70 inch blades(11 foot 6 " diameter?)I've seen almost 28 amps at 60 volts from this one.

                   Now if I was to build a second one keeping everything the same, but useing magnets 3 inches long instead,(3x1x1/2) What sort of power increase should I see? and next If I moved up from almost 12 foot diameter to say 14 foot with the longer magnets would that be a better match? I'd like to stay close to the 150 rpm cut in speed but see the top end increase to 30 amps or more, Am I on the right track?  Thanks
« Last Edit: November 20, 2005, 11:42:29 PM by (unknown) »

wpowokal

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Re: Planning my next Wind turbine
« Reply #1 on: November 20, 2005, 05:06:55 PM »
Shadow, I will leave that theory to others but how did your tower work out? You commented that you may have to shorten the top  pipe.


Oh yea don't underestimate the additional forces on the future tower by the increased rotor diamiter.


allan down under

« Last Edit: November 20, 2005, 05:06:55 PM by wpowokal »
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Shadow

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Re: Planning my next Wind turbine
« Reply #2 on: November 20, 2005, 06:22:38 PM »
Hey Allan, The tower is working awesome! I lowered the extension pipe by about 2 and a half feet, it seem to lower the weight down closer to the tower.I can raise and lower the tower in about 15 minutes by myself. I realize the additional forces, but I think I'm still under the rating of these towers, I havent weighed the old 32 volt gear driven generator,with the 8 foot blade,and large scoop governers, that was mounted on this tower, It must have been 200 pounds easily without the tail. We used a tractor with loader to load it in my truck. So I think these towers are fairly cabable, as we've had some very strong winds in the last 60 years. I often wonder tho what is the weakest part of the tower? Would the legs buckle down low?..or top portion of the tower fold over?  Hope I never have to find out.
« Last Edit: November 20, 2005, 06:22:38 PM by Shadow »

Flux

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Re: Planning my next Wind turbine
« Reply #3 on: November 21, 2005, 01:29:55 AM »
Taking the prop to 14ft from 11' 6" will make quite a difference. The wind speed for 28A will come down from about 30 mph to 22 mph ( roughly, gives you some idea)


The 3" magnets should be fine, keep the same inside magnet diameter and increase the disc diameter to fit them in.


150 rpm seems a bit fast for 14 ft if you want to use the low winds, tsr at 7 mph is about 12 for 48v and batteries will be higher a lot of the time. If you want to do the best in higher winds 150 will be fine. That should work out somewhere near 90 turns of perhaps #15.


Perhaps 100 turns would be a good compromise, 110 would give the same cut in tsr as you have now. You will know how it behaves at the higher battery voltages now so you can decide how slow to go. If you have plenty of wind it may be better to trade a bit at the low end for better output in high wind, you know your needs best.


Flux

« Last Edit: November 21, 2005, 01:29:55 AM by Flux »

nothing to lose

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Re: Planning my next Wind turbine
« Reply #4 on: November 21, 2005, 03:09:41 AM »
I am just geussing but I think perhaps the center of the tower would be the most likely to buckle. Perhaps it also denpends on the type of tower.


My thought is the flexing force if it started swaying perhaps in a gusty storm would be greatest at the center. The top is kinda free to float around without much stress from bending till it hits something solid that does not move. The closer you get to the ground or wider area is where you get to the part that does not move much. Now looking at it from the ground up, the legs or base can't sway and move because they are solidly planted, so the bending flexing force would be greater the further you get from the solid base. I would think the two points would meet near the center myself.


Of course like any chain, it's the weakest link that breaks, so if you have a bad top or bottom that would go before a strong center.


Looking at real life, most things that get blown down seem to be about center that they break also. Pics of towers standing fine half way up, the rest on the ground. Trees in a bad storm, unless the roots don't hold or they are rotten normally they break in the center.


We had a toronado come through nearby a few weeks ago. It trashed a ton of good healthy oak trees. Most broke in half in the center. Some up rooted. I don't think I really saw any that actually "broke" at the base though. Not sure if any healthy trees broke the trunks at the tops or not, I don't think so, I saw some that were hollowed out (rotten centers) that broke at the top. Many solid healthy trees snapped off about center.

 It was a mess all over the road and crews cleaning it up as I drove by.

« Last Edit: November 21, 2005, 03:09:41 AM by nothing to lose »

wpowokal

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Re: Planning my next Wind turbine
« Reply #5 on: November 21, 2005, 04:55:15 AM »
Shadow, I do not personally know where the week point is I have not seen those towers downed. Sometimes the head, as in water pumping tower takes off, the one we have "Trivio's" conversion on is older than me (40'tower).


I believe the strenght is in the flexability of the tower, a twisting wind may down a tower though. I would still be somewhat warey of fitting a blade diamiter greater than would have been alocated to the origional tower purpose, wind pressure on blade swept area is IMHO easy to underestimate.


Yes, I too purchased an old Dunlite (OZ version) 32V VP unit, its so heavy I doubt if I will ever refurbish it.


allan down under

« Last Edit: November 21, 2005, 04:55:15 AM by wpowokal »
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electrondady1

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Re: Planning my next Wind turbine
« Reply #6 on: November 21, 2005, 05:44:44 AM »
shadow i'm curious as to how you made out on your attempt to generate heat /hot water from your mill?
« Last Edit: November 21, 2005, 05:44:44 AM by electrondady1 »

DanB

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Re: Planning my next Wind turbine
« Reply #7 on: November 21, 2005, 07:01:29 AM »
I expect youll need larger diameter magnet rotors... 14" at least, if your to have room   for the coils.
« Last Edit: November 21, 2005, 07:01:29 AM by DanB »
If I ever figure out what's in the box then maybe I can think outside of it.