My first Wind Turbine

[Murlin]

I have decided to build a wind turbine.

Since everything is always done on a large scale in Texas, it just doesn't seem right to start off building a small turbine....

So I have decided to just jump in with both feet and hope that when I get in too far over my head, you guys might throw me a lifeline before I go down in flames so to speak...

I want to build a 48 volt 20' machine.  I know it is pushing the limit, but I am a firm believer that there is ALWAYS a workaround.

From what I gather, dissipating heat in the stator is the main concern in the larger machines.

I have run across a new epoxy system and was wondering if any of you guys have ever used it.

http://www.resintechgroup.com/casting.html

With this resin I was planning on designing a stator mold that would incorporate a heat sink design around the parameter.

Along with cooling fins around the outside of the stator, I was considering casting legs, coming off the main stator body that you would drill out for the SS all-thread.  Instead of the current stator mounting brackets, I was considering welding a flange on the hub.  Then bolting a thick, aluminum, roundish plate with a heat sink design machined into it's surface.  The legs extending off the stator would contact the heat sink and further draw more heat away from the coils.

The magnets would mount in recessed pockets about .08" deep and be secured with one flat head SS cap screw through the center. Tapping a blind hole into the magnet.

Grinding a small notch and center punching a burr into the notch on the head of the screw, would stop it from ever backing out.

I was considering not even using epoxy on the rotors at all.  This would cause the gaps between the magnets to move air as well.

Does this make any sense? or am I over engineering?

Murlin

[Nando]

No, it does not make any sense AT ALL.

You are LACKING engineering voltage wise!!

A high voltage is in order -- with peak voltages around 300 - 380 volts at peak Wind Velocity

The first GOOD engineering step is NOT to produce the heat, therefore there is a need of a high voltage generation with a conversion on the ground -- this way a light wire can be used to bring the power down to the load.

Not more than 15 % power should be dissipated by the generator at maximum power output -- 8 to 10 % maximum dissipation would be a much better design.

Nando

[kitno455]

you cannot tap the magnet. too brittle. also what out for getting any metal part of the stator mount in the path of the mags. even if it is non-magnetic metal, it will still get quite hot with eddy currents.

do yourself a favor. build a small one first. you like the third guy to come on here with this texas 'damn the torpedoes' stuff. i seem to recall the others later wishing they had started small...

allan

[Murlin]

You are correct I am lacking in electrical knowledge. I have no plans to make a stator that will run hot in the first place. I plan on doing my homework and try to design the most effecient alternator possible.   but, Keeping it cooler would not make it last longer??  

I have been doing alot of reading and from what I have read, there is alot of concern over heating of coils and magnets comming off due to thermal expansion of the epoxy system that has been used.  I have seen many, many, pictures of magnets comming off rotors.  Bolting them on in a retaing pocket made sense to me.

The 870FT claims to be of extremely high thermal conductance and very low thermal expansion.

I cannot see how this makes no sense at all. But I will take you at your word as I am inexperienced in these matters...

Every thing electrical generates a certain degree of heat. Heat IS the killer of electrical devices.  It made sense to me.....Sometimes things do not always work in the field the way they are designed on paper...

Murlin

[Murlin]

OK so it was a dumb Idea.  I could have swore that I have seen magnets bolted down inside motors before.  But maybe it was a diffrent material than the oned they make now.

Sheash, whats with all the attitude guys?

I am gathering information and asking questions and you guys want to cop an attitude.

Not really nessessary.

But I can see more reading is required.

And I will build a large mill.

There is no reason to build a small one.  A small one will not make any electricity.

I was just trying to have fun in the process.

The main reason for this post was the epoxy system anyways....So I threw in some lame Ideas....

Murlin teh lighten up

[willib]

Murlin there are a few designs i like , this one in particular is well documented

http://www.fieldlines.com/story/2006/5/28/134138/175

The parts are easy to come by , the rotors are from pep boys , the hub is a standard trailer hub , although i might have tried for a ford rear wheel hub and backing plate ,from a junk yard ( from a front wheel drive ford ),  because it wold give you something to mount the stator to.

also the wheel hub has four mounting holes , it is a beautiful design all in all

[craig110]

Hi Murlin,

I'm not one to always say "start out small."  As long as someone knowingly understands and accepts the risk of what they are attempting, so be it and have fun.  One caution that I'd give, however, is that an efficient windmill (which means, first off, that it doesn't self-destruct ;-) requires a delicate balance between the props, generator, and load.  Diving right into a big windmill increases the chance of something being out of balance.  (The larger power, especially when there are gusts, lowers the margin of error you'll have in everything.)  I'd suggest keeping your enthusiasm high, but read everything on this site a few times to really understand the issues and then post "how does this sound?" kinds of notes before building anything.  This way, you can use the experience of the very helpful folks here to avoid potentially expensive pitfalls in a large-windmill plan.

And, at the risk of sounding like I'm suggesting "start out small," one thing to consider is that in the time it takes to become so familiar with the concepts that a large windmill is do-able, you might be able to do a, ahem, "prototype" (I don't want to say 'smaller' ;-) windmill as a learning tool.  I don't know about you, but the first time I do just about anything it always takes a lot longer than I expected, and a large windmill would take an experienced builder a long time to begin with.  If I was starting out trying to get a large windmill as soon as possible, I'd probably get it done sooner by making my mistakes on a smaller one.  Tripling a one month project due to problems and then doing a six month project gets the large one done in nine months.  Tripling a six month project gets it done in a year and a half...  So, as counter-intuitive as it sounds, sometimes the fastest way of getting a large project done is to do a prototype first to work out the kinks.  (If it makes you feel better, you can call the prototype a "Rhode Island" sized windmill. ;-)

Craig

[zubbly]

hey Murlin,

why not try a conversion.  from all the ones i have done, heat does not seem to be a problem in the stator.

you should be able to achieve  100 watt per cubic inch of mag material with round magnets and 1.4 to 1.5 times that with rectangular magnets.

just an alternative for you.

zubbly

[Murlin]

Thanks, I have seen that post also.  I have read that the round magnets are not as good as the rectangle ones as far as gentrating power is concerned.

My main concern is to be able to build a large enough machine to compliment a 2.5k solar system.

I think If I can build a 20' machine, I can generate another 2k in the lower winds and just keep it furled up and not run it close to max output at all to make it last a long time. My average wind speed is 14 MPH.

I am not doing this for a hobby.  I plan to live off the grid.  

Since I own my own machine shop and have a good sized CNC mill, making any part I need is not a problem at all, I have all the tools.  I have been in building and designing molds and dies for the last 30 years. I also have a seat of Mastercam, and have access to Proe at work if anyone needs any CAD-CAM work done.

But like Nandu says, I am lacking in electrical expertise, even though I have wired in every 3-phase machine I have ever owned for the last 20 years, I don't have any experience in making alternators.  But hey, you don't have to know how if you have friends that do.....right

EVEN though I have tapped 60 RC A2 tool steel, I hadn't thought about the magnet breaking or stripping the threads.

From what that other dude said, I am assuming that magnets are like cast and the threads will strip out too easy.  So I will prol just epoxy them into the retaining pockets to keep them secure and use a pin at the end like Flux said in one of his posts.

Murlin teh gung hoe!!!

[Murlin]

Well I do have several very large 3-phase motors....20-30 HP....

[Murlin]

Heh, thanks for not flaming me....all the prototype work has already been done right here.  And it didn't cost me any time or money

Murlin

[willib]

if you are worried about magnets flying off they can be bought with holes allready in them, for mounting purposes

[Flux]

I don't think any of the comments are meant to be critical, most seem to be constructive.

Old Steel alloy magnets were sometimes tapped, but neodymium magnets are a sintered composition with properties similar to lighter flints, they will not stand tapping. they can be had with holes and you could fit countersunk screws if you really wanted. They can be fitted without screws perfectly satisfactorily onto discs, but not so easily on the outside of a cylinder if you do a conversion.

What Nando was referring to was the fact that an efficient alternator should not make lots of heat in the stator, but his approach would need an extensive knowledge of electronics to control the output. It is the ultimate way but not often done.

Epoxy is fine for the stator, but you will likely run into serious trouble if you attempt any form of heat sink or fins on the stator, it could be done but you would need lots of experience, otherwise you will make eddy currents and more heat than you had before.

If you are content to use it in the lower winds only, heat will not be such a problem.

If you want to do your learning on a big machine that is fine, but the cost will be higher than on a small one.

If you want to get there first time, don't depart too much from what DanB has done and if you think you have a revolutionary idea, ask first, someone here will most likely have tried it or will spot any snags.

Flux

[wdyasq]

Murlin,

First, where in Texas are you? There are a few of us in the area just West to South West of Fort Worth who will be building mills in the near future.

I've always thought 'bigger is better'. Many years ago I read about Wally Minto's "Wonder Wheel".  The article stated a 40' one would produce more than enough power to air-condition a small to moderate size house in Texas. I gathered 140' of 10" pipe, a few hunderd feet of 2" pipe, ball valves to charge the thing, designed a hub and struts, bought more iron, had 16 or so eliptical end plates cut, built a stand for it to run on. Hired a certified pipe welder for a while, bought a bunch of refrigerant to run the thing.

Well, to make a long story short, I found out what Mintos failed to calculate for larger "Wonder Wheels". At first I wondered wht it didn't work. Then I wondered why I didn't cach what the designer failed to catch.

I figured out I could have purchased two new Cadillacs for what I had 'invested' in the folly. I remember feeling glad I had not sandblasted and painted it before the "trial run" and I had used propane for the refrigerant for the trial run.

~200 gallons of propane makes a large flare when vented. One needs to inform the local volunteer fire department is is going to be an "impressive" controlled burn.  I think scrap iron brought $20 a ton back then. I gave the 'scrap money' to the local VFD.

Build a smaller "prototype". It can be an inexpensive learning experience. The knowledge gained is priceless.

Ron

[electrondady1]

murlin, i am just a novice builder and am working on a much smaller scale than what you intend on doing . flux is one of the most knowlegable members of the site and i beleave he has given you sage advise. if you were to emulate danb's building techniques as best you can it would put you in a good position to achieve your goals .this will give you some time to researh and get up to speed on the latest stator/voltage output data to suit your needs.  

[mowind]

Murlin , i recently did a conversion on a 7.5 hp 3 phase  induction motor and will be posting results soon. i used 4 pieces of skewed and curved magnets measuring 6" x 2" x 3/8" .they  each came with two counter sunk holes. i just had to machine down the rotor and tapped the holes in it and srewed down the magnets with some brass machine screws ( stainless steel would have been better ). i did not use any epoxy.i bought the magnets on ebay as a special order. the seller also sells  block magnets with  counter sunk holes in them. maybe you can check it out if you don't want to use resin.it you are doing dual rotor you can probably use some hex nuts at the back instead of tapping the holes.

Mowind

[DanB]

I've got to throw my own thoughts in here.

"A high voltage is in order -- with peak voltages around 300 - 380 volts at peak Wind Velocity

The first GOOD engineering step is NOT to produce the heat, therefore there is a need of a high voltage generation with a conversion on the ground -- this way a light wire can be used to bring the power down to the load."

Perhaps true and it's surely possible to do what Nando is suggesting.  Most small wind turbines don't though - and the reason is because it's complicated and expensive.  I would love to explore this stuff and learn some tricks from Nando and Flux on improving alternator efficiency with electronics.  But it has its pros and cons.

It's very feasable to build a simple machine that's matched with resistance only and it will be reasonably efficient in low/common/average winds.  So it's only 50% efficient in higher winds...  so long as it can dissapate that heat without burning up then you'll have a nice simple system that works fine, and it's not difficult to build that way.  Most small wind turbines are as such.

'Good engineering' is a fine line between simplicity and performance.  In the 1920's there were model T Fords and there were double overhead cam miller race cars who's engines performance was better than most new cars today.  The model T was simple/affordable and almost anybody could understand it - it was the workhorse of the time and considering the cost/simplicity - I would say an example of 'excellent engineering'.

So I disagree - the first 'good engineering step' is to keep the project simple, reliable and workable and within your means.  Yes - there is always room for improvement though it may have its own set of costs.  At 48V I think you can build a machine that's very efficient in winds 8 - 15mph and if your charging batteries with a 20' wind turbine you'll probably have lots more power than you know what to do with in higher winds anyhow.

Just playing devils advocate a bit - Nando has his points, but I don't think that life has to be so complicated unless you enjoy/understand that sort of thing.

[Walt]

Murlin, I would also like to know where you are located in this great state.

You mentioned that you have CNC machines, have you thought about milling out the rotor a few thousandths to accept the magnets, that would keep them from sliding aroumd. I am working on a mill of similar size with a furling system so that it can be shut down when needed. Good luck on your project.

[dinges]

I'm not sure why the 'attitude' remark. So far I see only responses that try to help you 'get the most bang for the buck'. That this may mean you will have to re-adjust plans, so be it. I know you are from Texas and that in the USA big is beautiful, but geez... 20ft for a first genny? Wow...

I'm wondering whether you ever handled NdFeB magnets. I started with tiny ones, 3/4"x1/2"x1/8", then went on to 20x20x10 mm, and now am building my 3rd genny (10ft) with magnets of 2"x1"x.5". Personally I never would have wanted to start with the latter magnets. These things are dangerous if handled carelessly. It took working with smaller magnets and the smaller rotorplates to feel confident enough to tackle the 'large' stuff (10ft genny). A 20ft genny uses magnets of, say, 3"x2"x1"?! Yikes. Not to mention 2 rotorplates stuffed to the brim with such magnets.

Then there are all the other little things; winding coils; building a tower; building the bearing assembly, etc.etc. All become progressively more difficult and critical, IMO. Double the diameter means double the forces.

The Dans didn't start building 17ft and 20ft gennies till they made 20 or so smaller gennies.

Then again, it's hard for me to judge your mechanical and electrical engineering skills from a distance, behind my computer screen. But the way & what question you ask suggests to me that it might be a good idea to first brush up on the theory, before investing lots of money and time in a 20ft genny.

Just my opinion.

[dinges]

correction:

double the diameter means 4 times the forces.

[Murlin]

"have you thought about milling out the rotor a few thousandths to accept the magnets"

Yes I am going to do exactly that. It looks like there may be a 1/32" radius around the edges of the magnets from looking at the pictures.  So I will machine out a pocket only as deep as needed to keep em secure.

I am currently living south of FT W about 35 miles.

Murlin

[dinges]

Contrary to what your sig-line suggests, you do like an adventurous life; I'm much more chicken than you. I'd never burn-off 200gl of propane. Not at once, at least

How long did it take for the fire dept. to arrive? Did they share your definition of 'controlled'? Did you lose any facial hair in the process?

BTW, burning 200gl of propane seems like a big waste of all those kJs. At least, if you drilled a hole in one of those 4 balls and lighted at the hole, the "Wally Minto wonderwheel" would at least spin, for a while. Probably generate a lot of energy too, not too mention an impressive display.

"Ignorance can be cured. Stupid is forever." Sorry. Couldn't resist

Peter.

(Seriously. A story of the experience building this wonderwheel and its results that fall short of what the designer promised could be an interesting story to read. Might even learn a thing or two too, at least that history often repeats itself.)

[Murlin]

Ron you and I are prol in each others back yard

I appreciate everyones input and apologize if I sounded like a jerk...

I dug this out of my junk boxes, I think it might come in handy...A guy who used to work for me made it from a kit and gave it to me years ago.

But it is on life support .....I cant read a sine wave with it.  I think some transistors are blown....it only flatlines....

Luckily I have all the drawings on it.

The calibration gizmo has a blown 3/16 slow blow fuse hard soldered in.....

3/16 AMP?  Is that right??  Never heard of a fuse that size before....

Murlin

[dinges]

I see. You have a non-functioning oscilloscope. Which, if I judge correctly, you wouldn't be able to operate if it actually was fully operational. We don't call them drawings but schematics, BTW. It should be repairable by anyone knowledgeable, Heathkit built high quality kits, in their days. Don't start replacing fuses. Let someone find out what's wrong with it.

How do you expect this to be of assistance in building a 20ft genny? I've been pondering for a while and I can't think of a way in which a scope could be useful.

[Murlin]

So eddy currents can be created from a non conductive material?

I would never have guessed that....

I would have thought that since the stator was cast with epoxy, epoxy cooling fins sticking out would not cause any problems at all.

I see many many pictures of stators that have extra material protruding from around the extreme outside dia and those seem to work good enough....

Are you sure you understood that I was going to use the epoxy itself?

**sratches head*

And I know exactly what you are talking about new Ideas....that is why I am talking about them instead of jumping right in and doing.

Another idea I had was to use an anemometer to trigger an automatic shutdown switch. One can not be away 24/7 and may need the machine to shut down should it get too windy during the night.

Murlin teh somewhat lame ideaman....

[Murlin]

I was asking about the fuse....

I had it working about 10 years ago when I did some repair on my Gettys drives in my CNC.

I was checking for noise in the small control boards.

I blew the fuse in the calibration unit when I pluged it into the scope.  The scope has a problem and I will be sure to tell you what was wrong with it when I fix it

Don't judge a book by it's cover dude...

Have a nice day....

Murlin

[dinges]

I hope I'm not replying to Trizzybob here...

Who mentioned eddy currents in non-conductive materials? No one. You're right in scratching your head. In an isolator no current can flow. Also no eddy current.

You want to dissipate heat. Using a lousy thermal conductor like epoxy. Good luck. Don't think you will succeed.

As far as shutting down the machine goes... Do a search for 'furling'. But, to be honest, I think you are Trizzybob in disguise. Good luck with that 20ft machine.

Murlin, I have dozens of ideas per day. Most of them get shot down within seconds from conception. Others manage to last a little longer. Few survive a whole day, let alone some quick calculations. One isn't lame because one has ideas. One is lame when one isn't critical of them.

"Invention is 99% perspiration and 1% inspiration. Which is why engineers sometimes smell really bad."

[dinges]

[dinges]

Might as well answer that question.

Yes, 3/16 Amp is a standard value for fuses.

[Murlin]

Thanks, I will pick up one at the industrial electronics supply store Monday.

The scope had nothing to do with building a 20' mill. I should have made a separate diary entry for it.  I was just digging around in my electrical junk and run across it.  I forgot I had it.

And you are also right, I don't know how to use it very well, I just had some pictures of some waves in a tech manual on troubleshooting my drive units and to keep from spending 6k to have a tech fly in from Kali, I found it pretty easy to find the bad board.  I can set it up to read a wave and that is about as far as it goes.

But I did manage to keep my EDM machine, and CNC machines running for 20 years, simply by using the process of elimination and my volt meter, just checking base/emitter/collecter of the transistors.  There are not that many in the old style curcuts to trace down, and a transistors are usually what goes....that is about as far as my electrical expertise goes and I know its not that far

Man, I sure hijacked this post all to hell.....

Oh, well, it is my Diary

I will try to stay on topic....

Murlin

[kitno455]

1. if you have ever seen a neo magnet attached with screws, it was likely a small countersunk ss screw from the face of the mag, tapped into the rotor, not the other way around. the fact that you even want to try it indicates that you need to buy some small ones of these and break a couple before you spend lots of cash on big ones.
   
2. instead of drilling mags, why not put a roll pin into the rotor on the circumference, and one on either side? since you are in a dry climate, you wont need much more than that to hold the mags. these things (while still magnetized) are almost impossible to remove. again- try building a smaller one, and you will find your screw idea is overkill.
   
3. as of now, you have ~20 comments with useful technical opinions, at no cost to you, from some of the brightest minds in the homebuilt windmill business, and you have the gall to call it attitude? wow.
   
   

allan

[willib]

Holy crap !

did i miss a post here , i dont think i did

everyone just take a chill pill ,

i think the new guy has held up well considering everything thrown at him

[TomW]

Allan;

Well said:



 as of now, you have ~20 comments with useful technical opinions, at no cost to you, from some of the brightest minds in the homebuilt windmill business, and you have the gall to call it attitude? wow.



Yeah, attitude. Uh well if calling a spade a spade and honesty are "attitude" then this is the place to get yours.

Frankly this crap lately where we cannot honestly voice any opinion that impacts someones ideas in a non positive manner is just so stupid it makes me want to puke.

Like the couple I knew 20 years ago that refused to use "no" with their child in order to not impact him with negativity. Said child is dead because he did not understand that the world is not that rosy place with no limits his folks conned him into believing. Tragic but true.

The advice here is free and usually given in good faith. I am sure if one were to ask your question and wait long enough one of the local [clueless] know it all's will provide just the answer one wants.  Of course it may not be truth but it will make you feel good because someone said "sure it will be fine, go for it"

Sorry, I just get fed up with these folks that think any honest response that does not instantly worship the idea is somehow restricting quality thinking.  When you learned to drive your first vehicle you drove was not likely to have been a semi with 3 manual transmissions with square cut gears. Same goes for this hobby. Kind of like you need to crawl then walk then run.

So there you go, and that is an attitude. The simple attitude that some of you need to know what is inside the box before you think outside of it. Otherwise you may have a catastrophic "eureka" moment when it all comes crashing down with a high financial cost and unpredictable human cost.

I know some people are born with a serious medical condition known as cranial rectosis. Until the cranium is removed from the rectum no progress can be made. Not directly referencing anyone in this thread, just my opinion on the attitude if we don't buy your drivel we are bad people with evil intent to restrict progress.

Funny thing is not very many of these grand plan types ever report back with either success or failure which leads me to think they failed and are too embarrassed to admit it. Join here make one very wild post about some grand scheme stir things up then poof never heard from again.