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new wind turbine
By DanB, Section Homebrewed Electricity Posted on Thu Dec 04, 2003 at 07:20:52 AM MST
bigger and ?

I started on Thanksgiving day, after we had the house cleaned, food underway - I had a few hours to kill till the guests showed up! It's been moving along quickly since then.

As usual I'm working with the front volvo wheel bearing and hub. This time I've got 2 disks, 14" diameter cut from 3/8" steel. I had these plasma cut by a shop in town, they cost $20 ea.

I cut out the center hole 3" diameter with a hole saw. A good hole saw has no problem cutting through 2 disks at once so long as it runs slow enough and has enough oil on it. The holes for the studs are 1/2".

Pictured above the two disks are done, and they fit the hub pretty nicely.

The magnets for this machine are pretty large. 16 of them fit together to form a ring with 8" inner diameter and 14" outer diameter. They are wedge shaped. In this machine I'm using 12 per rotor so there is a bit of space between them (about 3/4"). I worked out what seems a reasonable coil shape/size and made the coil winder which is shown above.

I layed out where the magnets go and used a center punch to mark their locations. Placing them went pretty quickly. As each magnet went into it's place I used super glue to tack them there so they'd not be sliding around on me as I placed more.

I cast the magnets in resin as shown above, and mounted the back rotor to the wheel hub.

I drilled and tapped 3 holes in the front rotor so I could have 3 jacking screws to make lowering and raising this hopefully a safe and smooth operation. So far it seems to work nicely - takes a bit of time, but it goes very easily!

I got most of the metal work done on the main chassis here. It's about the same as the last ones... hope it's strong enough!

Another shot of the same thing...
The tail boom is 7' long right now. My goal here is a 14' prop, although once I start testing coils I may find that slightly smaller is more appropriate. My biggest concern right now are the forces on the tail pivot. It pivots on 1" shaft (instead of pipe like the last ones) and seems quite strong, but after seeing some bending/stress on my current 9' dia machine I'm wondering a bit. This will be a 12 volt machine, so I'll probably (hopefully!) be dealing with a lot of current. Well see what happens... it'll be fun no matter what!

new wind turbine | 16 comments (16 topical)

Re: new wind turbine (none / 0) (#1)
by Guerreiro on Thu Dec 04, 2003 at 07:34:19 AM MST

Great job. I'm building one wind system myself and I'd like to know, when you finish this Generator, how much power is it outputing.
Continue the magnifig work.
Miguel

Re: new wind turbine (none / 0) (#2)
by monte350c on Thu Dec 04, 2003 at 07:40:09 AM MST

Hi DanB,

Nice One!

What are the details on those wedge-shaped magnets you're using on this one? Also I've been looking for some definitive info about how much temperature fiberglass resin will take in the stator before bad things start to happen.

I was able to find some info on the web about epoxy resin - there's instructions on the West systems site about how to remove epoxy/cloth - you can heat it to 200 F and it will start to soften. But I haven't been able to find anything about plain old polyester resin, the type I've been using in stator casting.

I've seen several mentions of adding talc to the mix, and one site that said this helps increase the resin's capabilities to withstand temperature. Have you had any experience with stator problems due to heat?

What wire guage will you be using in this stator - or have you decided yet?

Very interesting project, I think there might be a lot of mileage in the increased diameter units!

Ted.

Re: new wind turbine (none / 0) (#3)
by DanB on Thu Dec 04, 2003 at 07:49:16 AM MST

Hi Ted -
like I said, the magnets are such that 16 will form a "ring" 8" ID and 14" OD, and they are 1/2" thick. It's interesting to note, that even the 3/8" steel is not quite thick enough... they are slightly magnetic on the back side. I've got 120 of these - they were (unfortunately) rather expensive.

REgarding the resin and heat - I think about this sometimes. Fortunately making a new stator is not too difficult!

But I believe it really boils down to keeping things within reason with the coils. I can wind it for whatever cutin speed I want, but the resistance must also be low enough so that too much heat is not generated while it's handling the power from whatever size prop I put on it. If resistance is too high, that'd mean I probably wound it for too low a cutin speed, put too big a prop on it - and at higher power outputs I'd expect it might melt! So it'll take me a bit of trial and error poking coils in there while the rotor is on the lathe to figure out what's appropriate. (I hope!!) Another issue of heat is obviously the furling system - to have it turn away from the wind in time. There is a lot of talk about stator cooling etc... Im really not sure if it's an issue or not yet to be honest. I've not seen any problems with it yet on past machines. My guess is folks have problems with it when resistance is too high. Im sure you could push the limits a bit more by cutting holes in the stator or some means to improve cooling, but my guess is that the "limits" are already well within reason so long as the coils are wound well, and the machine furls at the right time.

Time will tell...

[ Parent ]

Re: new wind turbine (none / 0) (#5)
by windstuffnow on Thu Dec 04, 2003 at 09:37:25 AM MST

Nice machine Dan! Just tossing some numbers around and the size of the magnet sections I believe a 7kw machine could easily be built with them. ( single rotor with silicon laminants ). Using 12 of them as you have I calculate 2kw at 300 rpm and 4kw at 500 rpm. My numbers were using 36 slots and 8 turns of #12 wire per coil. If it went beyond 2kw for extended periods of time it may require some cooling but its all do-able. I take it your looking for 2kw+ from it?

Looks like fun to me!!!!

Ed

Have Fun! Windstuff Ed
[ Parent ]

Re: new wind turbine (none / 0) (#10)
by DanB on Fri Dec 05, 2003 at 07:09:33 AM MST

interesting numbers Ed.... Im really not quite sure what to expect from the dual rotor, and I suspect Ill have less than perfect coil design. If it works out to be 14', and I think thats what Ill shoot for, then I suspect top speed will hopefully not be more than about 350 rpm.

I've messed with it a bit this morning trying to figure how to wind the stator up. It's fun after building a few one starts being able to make a "good guess" - and my good guess seems to be very nearly confirmed by actually testing a coil in it this morning on the lathe. I think what will fit (barely) and get a good cutin speed around 75 rpm is 32 windings made up of 3 strands of AWG 14 wire. (I think thats close to AWG 9 wire). And there'll be 3 coils/phase (total of 9 coils) and it'll be wired in star. Since AWG 9 wire would be pretty difficult to wind, I'll make it up from 3 strands of 14.

Should be fun, well see how today goes. If I'm ambitious perhaps I'll have the stator done by days end. Lots of fun ahead!

[ Parent ]

Re: new wind turbine (none / 0) (#13)
by monte350c on Fri Dec 05, 2003 at 09:49:25 PM MST

Hi DanB,

At the risk of sounding heretical - why not try a setup that produces some higher voltage AC for this unit? Like around 120...

If you were using a 3 phase stator, wound with 14 AWG, it should be able to handle 17 amps without excessive heating. 17 x 120 = 2,040 watts x 3 phases = 6,120 watts.

Then transform, rectify, heat, or otherwise use the power at the source of the load. You could probably use a run or two of inexpensive 12 / 3 to convey the power from the pole to the load.

Just a thought!

ps. when I asked about details for those magnets - I was mainly interested in how much $$ and if you'd be putting them on wondermagnet.com for sale!

On cutting disks - I had the pair made for the alternator I built at a local machine shop, though by abrasive water cutting not plasma. The water cutting machine is pretty cool - it uses garnet (like on sand paper) fed into a high pressure water jet. The whole thing is run by computer so I had 4 pie-shaped holes cut into the 17" disks to lighten it somewhat, and the center hole and bolt holes done at the same time. It didn't cost any extra either.

I'm finishing up a set of foam-core epoxy / fiberglass blades also in 14' diameter right now. The cores are cut with a hot wire, then covered with epoxy and fiberglass cloth, then vacuum bagged. Sounds like a lot of trouble, but the whole process is actually quite easy and makes a very light and strong blade. Mine will have a 24" diameter "hole" in the middle to clear the alternator assembly. So the blades themselves are 6' long, and start 12" out from the center of the hub. This really is a lot of fun - good luck with this project and looking forward to your next posts!

Ted.

[ Parent ]

Re: new wind turbine (none / 0) (#14)
by DanB on Sat Dec 06, 2003 at 07:05:35 AM MST

Hi Ted -

you asked... "At the risk of sounding heretical - why not try a setup that produces some higher voltage AC for this unit? Like around 120...

If you were using a 3 phase stator, wound with 14 AWG, it should be able to handle 17 amps without excessive heating. 17 x 120 = 2,040 watts x 3 phases = 6,120 watts.

Then transform, rectify, heat, or otherwise use the power at the source of the load. You could probably use a run or two of inexpensive 12 / 3 to convey the power from the pole to the load."

- I could, and it would make some sense for sure. Like everything I think doing that would have its pros and cons. The transfformers would be expensive and have their own losses. I think most of my power is in the low winds, so probably 90% of that which comes in will be under 500 watts - here, 12 volts is reasonable. And, my tower is pretty close - only 100' from the house. But yes - should I ever build a large machine that is a greater distance away, I think seriously about playing with transformers. could be that I should be doing that now... hard to say.

You asked about the magnets - Ill list what I have (not many of them) on our shopping cart soon for $20 ea. These are kinda expensive - special shapes cost more than normal disks or blocks, and I only got 120 of them so they are costly.,

[ Parent ]

Re: new wind turbine (none / 0) (#4)
by cevonk on Thu Dec 04, 2003 at 07:57:05 AM MST

And they say size doesn't matter.....

It looks very nice. From the dimensions you gave regarding the diameter of the magnet placement, it sure sounds as if these are very large magnets.

Excellent pictures! I can't wait to hear how it works.

Re: new wind turbine (none / 0) (#6)
by Barnac on Thu Dec 04, 2003 at 12:16:02 PM MST

DanB,

Why didn't you ask the plasma shop to cut the 3" hole and the 5 1/2" holes for you ? A friend of mine owns a sheet metal laser cut shop and it's seem to me that it doesn't take much more time or effort for them to cut additional holes. The most time consuming part is to set the sheet or plate on the X Y table. Its only a little more of info to put in the program, since its all computer driven. Maybe they are not using the same technology. Just wondering...

Keep the good work.

Barnac from the cold Montreal today. Winter is really knocking on the door. Go habs habs go :-)

Re: new wind turbine (none / 0) (#7)
by zubbly on Thu Dec 04, 2003 at 06:21:25 PM MST

hello DanB.

only one thing to say, Beautiful job. i hope it works great.
i have one question and just one concern.

are those neo magnets? i just didn't see where or if it said.

my concern is those huge magnets. the size so large and the ATTRACTION to each other on opposite plate so powerful, i am wondering if the resin is sufficient in strength to keep them in place once the alternator peaks out on its temperature rise.

every genny is a step closer to a greener world-----zubbly

Re: new wind turbine (none / 0) (#12)
by DanB on Fri Dec 05, 2003 at 04:29:02 PM MST

Hi Zubbly -
the magnets are Neo's. I don't share your concerns here (perhaps I should!) for a couple reasons.
first - they are neos and they are stuck down very tightly all by themselves! The resin surely helps. secondly - being a larger machine, it hopefully will run pretty slowly, 400 rpm would hopefully be very top speed, - hopefully a bit less actually. Lastly - the magnets, and the magnet rotors don't heat up much I shouldn't think. All the heat is in the stator and the magnet rotors are isolated from the stator by a layer of moving air, so I doubt they get very warm at all. Fun stuff.. time will tell.

[ Parent ]

Re: new wind turbine (none / 0) (#8)
by BruceDownunder on Thu Dec 04, 2003 at 07:10:04 PM MST

Bloody lovely job Dan, well done -- and your pictures just add that special touch- I'm thinking (well,actually, have sawn the blanks) , of a 12 foot mill -three 6 foot blades--a bit slow , but could develope a fair bit of power for my dual F&P stators--when I get around to it.

Congratulations on your lovely work

Bruce.

Re: new wind turbine (none / 0) (#9)
by iFred on Fri Dec 05, 2003 at 12:50:35 AM MST

Nice, REALLY NICE! Thanks for sharing Dan! This stuff is tooooo addictive!! It looks that that thing is going to put out some serious power.. Let us know how this turns out! Good Luck!

>> all energy used to produce this comment or post came from solar and wind energy! It works!

Re: new wind turbine (none / 0) (#11)
by JW on Fri Dec 05, 2003 at 09:24:40 AM MST

Looking at windstuffnow's post and falls over in chair. Personally I would not doubt these numbers could be possible. Thinking about some of Electric Ed's post's, noticeing the spacing of the magnets (with 12) on the rotors. Reminds me of this day along time ago, sitting in class, with a collage professor telling us "there is no way to improve the efficiency of an automotive alternator" then he went on with some mumbo jumbo about the supieror waveform that the stator produces blb bla bla. then theres the non-clogging aspect of these dual rotor machines.

Considering DanB is using a star wiring pattern, AC could be the intended output. Great Job DanB, your work is very impressive...
-JW

[ Parent ]

Re: new wind turbine (none / 0) (#15)
by RobD on Sat Dec 06, 2003 at 01:34:21 PM MST

Nice Job Dan!,
what do you expect the final weight to be and how high is it going up?
RobD

Re: new wind turbine (none / 0) (#16)
by Harry Luubovv on Wed Dec 31, 2003 at 11:34:00 PM MST

Congratulations DanB ! ! You do wonderful jobs with this large mill ! Hope I am able to do as far as you do ..... oneday.

Work the good, good to Keep.

Keep up the G/W ! ! ... and ... H N Y !

Harry Luubovv.

[ Parent ]

new wind turbine | 16 comments (16 topical)

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