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stator heat again
By pepa, Section Wind Posted on Sat Sep 15th, 2007 at 03:40:35 PM MST
what if?

Stator cooling. What problems would I have if I placed three large size wire coils around the outer edge of the stator that would be outside the range of the magnetic flux and in the area of the stator that is exposed to the wind. Each of these coils would be tied to a phase of the stator winding by a relay that is controlled by a switch that would reset itself after it cooled down. The relay would tie the large coils into the system when the overload switch kicked out to add resistance to the coils of the stator and help dissipate the buildup of heat. Has anyone tried this? pepa

stator heat again | 27 comments (27 topical, 0 editorial)

Re: stator heat again (3.00 / 0) (#1)
by Nando (nando37-at-tx-dot-rr-dot-com Correct theanti-spam) on Sat Sep 15th, 2007 at 10:10:25 AM MST
(User Info)

Pepa:

The solution is to avoid the overheating of the stator.

One of the solutions is to have a charge controller that allows MPPT in front of the battery bank. -- this implies that the wind mill will be allowed to produce higher RPM , therefore higher output voltage, for the charger to do the power conversion.

This way the generator my be in the 80 to 85 % power transfer, instead of the 45 to 53 % when charging a battery bank directly, where the bank behaves like a high power Zener ( clamping voltage) which forces a lot of generator internal dissipation.

Another way is to detect the charging current with certain value defined to a maximum of generator internal power dissipation.
Once this point is reached the tail setting is modified with a motor and screw to place the setting weight to a lower furling point.

Also, the most effective and for sure safe for many conditions, like high winds, is the use of a Torque Pitch Controlled Hub - the safest because the power harvested is defined by the load and if the load goes away, the RPM is automatically lowered ( under high or low wind velocities conditions).

I wonder when one of these experimenters is going to build one TORQUE PITCH CONTROLLER HUB.

No more generator overheating, no more over - RPM, controlled wind mill by just removing the load -- the TSR is set to 1 or even less.

In the past, I presented a centrifugal pitch controlled wind mill generating 11 kw, which is almost as good as the Torque Pitch Controlled Hub.

For the low watts ( around 1 - 2 kilowatts) the Hub can be simple.

Nando

Re: stator heat again (3.00 / 0) (#2)
by pepa on Sat Sep 15th, 2007 at 10:52:10 AM MST
(User Info)

thanks Nando for the reply, i have been studying youe post on the 11 KW pitch control and i would like to build one when i have time. i posted a sliding tail weight for yaw control a while back that should work as well.

pepa

[ Parent ]

Re: stator heat again (3.00 / 0) (#26)
by snowcrow on Fri Oct 5th, 2007 at 09:07:28 PM MST
(User Info)

pepa, how about something this: A tail flap furling assist. Just a solenoid, SCR, and a NTC thermistor in the stator as the SCR trigger. You would also need a rectifier bridge at the turbine, and isolated from the batteries for the solenoid to reset after the turbine slows and the stator cools down. The flap on the tail is cut at a slight diagonal, with the top being larger that the bottom. This will allow the wind force to lift the tail upward as well as into the furled position. I know it's cured and I'm not most of an engineer, but it's my two cents worth!!

Blessings, Snow Crow

[ Parent ]

Re: stator heat again (3.00 / 0) (#27)
by pepa on Sat Oct 6th, 2007 at 09:09:42 AM MST
(User Info)

thats a good idea Snowcrow, i think it will work, pepa

[ Parent ]

Re: stator heat again (3.00 / 0) (#3)
by Warrior on Sat Sep 15th, 2007 at 11:21:12 AM MST
(User Info)

Hi Nando,

I have machining facilities at home. Can you give us more details regarding the torque pitch control? I understand the centrifugal but the other one you mention I have no idea.

Maybe a picture?

Thanks,

Warrior
Warrior__ "Why can't Murphy's Law be used to my advantage??"
[ Parent ]

Re: stator heat again (3.00 / 0) (#4)
by Nando (nando37-at-tx-dot-rr-dot-com Correct theanti-spam) on Sat Sep 15th, 2007 at 11:25:37 AM MST
(User Info)

Warrior:

Send to me your email address, correct mine for the anti-spam

Nando

[ Parent ]

Re: stator heat again (3.00 / 0) (#6)
by jacquesm (j@ww.com- I run a whitelist, add 'stjoes' to msg) on Sat Sep 15th, 2007 at 12:17:50 PM MST
(User Info) http://www.greenbits.com/

Hey there 'nando', I just left you a little note in the page about 'your' design...

http://www.fieldlines.com/story/2007/4/3/171347/0975

cheers mate, and keep up the good work.

Jacques.
www.greenbits.com
[ Parent ]

Please, please stop (3.00 / 0) (#7)
by TomW on Sat Sep 15th, 2007 at 12:37:33 PM MST
(User Info)

Nando;

What part of open forum discussion don't you get?

This constant luring people off the board for whatever purpose is unacceptable.

I have tried to tell you this many times.

Are you retarded, stubborn or don't care about the whole point of open discussion and peer review of same?

Just stop luring people off the board. I am fairly certain why you do it and I am quite certain it is not for the general good.

This is where you claim I am picking on you and misread my point. No need to respond just stop with the trying to lure folks away for whatever purpose.

Anyone lured away like this please be careful.

By the way, who really designed that 11KW turbine you keep bragging about? Interested readers should check out this link: http://www.fieldlines.com/story/2007/4/3/171347/0975 And follow through to the link to a story from 2004 Jacques posted near the bottom

DanB has asked me to not kill these "contact me off board" posts, so you can thank him that they stay at all because it ticks me off so bad I would kill them on sight every time. He is a bit more tolerant than I am of this kind of thing. I have not actually pressed my case about it to him but believe I could convince him your intentions are not what you represent them to be but I have too many real world projects going on to waste energy on fighting evil here. I do have time to turn some light on to find any cockroaches and see them run because a cockroach hates the light shining on it.

In my official capacity... STOP

TomW

[ Parent ]

Re: Please, please stop (3.00 / 0) (#19)
by Nando (nando37-at-tx-dot-rr-dot-com Correct theanti-spam) on Sat Sep 15th, 2007 at 10:38:44 PM MST
(User Info)

TOM:

I assist people AT NO COST under my conditions and NOT under your conditions

For one, I need to know the person capabilities to see if the person is capable of proceeding with the project to the end..
Tom said:
>DanB has asked me to not kill these "contact me off board" posts, so you can thank him that they stay at

I say: because DanB knows that I am doing my assistance in a proper manner.

You, in a very dishonest way took the words of somebody else and assumed facts which are NOT real, I HAVE NEVER SAID THAT I DESIGNED THE 11 KW CENTRIFUGAL WIND MILL.

I never bragged about the wind mill, I complained about it. -- better go read again WELL.

Assist, does not mean design -- Also, I do not like the centrifugal, it has about the same problems that the furling units have if not properly built -- for one high RPM at no load.

One thing is an open discussion of a problem, another thing is to assist somebody with a problem that may take a long time and to have discussions that are not for the forum to have access. ( for diverse personal reasons ).

I may assist people with conditions and those conditions are not for you know and this is making you go crazy as you have shown it several times.

Or after one of your attacks, I respond and you of course erase my reply from the server for no body to see it, as I have expressed it to DanB, which clearly shows how biased you are.

From the beginning you have attacked me and my response really ticked you off, still the same work stands.

I challenge you to find one person that can say that I charged for MY assistance, even though in previous messages you try to IMPLY that somebody said that I was charging for my assistance -- You are really biased --. HONEST ??

Why don't you first TRULY find out what you are trying to imply is true or NOT, We may thank GOD that you were not a policeman in early times -- oh God.

You continue attacking, even indirectly like a rattlesnake, just read again your last statement in your message.

The American Indians use to call certain people : forked tongue -- too bad Tom you do such damage.

By the way ask "Jacquesm " from which patent did he clone his centrifugal hub, after the initial patent all designs are clones with variations.

Do you know why the Torque Pitch Controlled Hub is not so common ?.
Search for some patents if you know how, it may teach you something of high value --

What a waste of time --

Nando

[ Parent ]

Re: Please, please stop (3.00 / 0) (#23)
by jacquesm (j@ww.com- I run a whitelist, add 'stjoes' to msg) on Sun Sep 16th, 2007 at 11:31:52 AM MST
(User Info) http://www.greenbits.com/

Dear mr. Hernando J Garcia Vasquez,

I think you have crossed that fine line between discussion and not permissible aggression. You picked the wrong fight imnsho.

TomW is one of the most respected members of this community, his only shortcoming is that he calls a spade a spade and you seem to take that as an insult. It was really nothing but the establishing of a fact. Toms biggest fault in your view seems to be his honesty. I wished I could say the same about you.

I've done some research on you and what I've found is quite impressive. You are a retired electronics engineer that has created an online persona that pretends to be a living legend in the field of renewable energy, and all that without ever leaving your computer. You trade information back and forth between various fora and people adding little lines like 'I designed', 'I adviced' and 'we collaborated' slowly building a web of respect that is absolutely not yours to claim.

You are just a radio amateur, not a wind/renewable energy specialist, you have never in your life designed windmills and / or renewable energy systems professionally or otherwise and you are not a structural engineer.

You are a gifted social engineer, that's the one compliment I will pay you, but it is on par with calling somebody a gifted thief. Not a reputation to be proud of. You have managed to ingratiate yourself with just about everybody who is somebody in the field and you use bits of information that you pick up here and there as the currency with which you increase your status.

All of this is fairly well documented online, as is your complete personal history but I will spare you the embarrassment full publicity, anybody that can use google can dig up what I've found. From the above you know that what I speak is the truth and that if we know this much we know the rest as well.

Your first language is Spanish, which explains the sometimes hard to understand structure of your writings. However that does not excuse you from the tripe that you have written above here.

If this were my forum, which it is not, that would have been your last post. I don't care if you're old, retired or just plain spiteful but language like that has no place in civilized discourse, even when you're on the losing end. As far as I'm concerned you've lost your right to speak because you are not able to take your lumps when they're dealt out fair and square.

So, when is one of these retired, ex rockwell electronics engineers going to come out like a man and give us the whole story of how he has been playing both ends against the middle this long ?

best regards,

Jacques Mattheij
www.greenbits.com
[ Parent ]

Re: Please, please stop (3.00 / 0) (#24)
by TomW on Sun Sep 16th, 2007 at 01:30:13 PM MST
(User Info)

Jacques;

I knew it. Just as I have been warning folks.

Thats the last comment from me on this thread.

I hope web space elsewhere will contain details for those who want to know them, though.

And, thanks for pointing out the sometimes subtle difference between "jerk" and "honest".

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

Re: stator heat again (3.00 / 0) (#8)
by jacquesm (j@ww.com- I run a whitelist, add 'stjoes' to msg) on Sat Sep 15th, 2007 at 12:38:12 PM MST
(User Info) http://www.greenbits.com/

I think before you go and execute 'nando's' design you will want to be aware of the engineering challenges of variable pitch hubs and that since nando didn't really design his his advice is probably going to amount to an interesting way to get killed.

Copying something does not mean that you understand it, and copying it wrong is sometimes only stupid, in windmills it is possibly quite dangerous.

Variable pitch, while technically imho the best way to build a windmill is also the hardest to get working reliably. in the drawing in Nando's files there is almost 0 margin with respect to fatigue issues, and the governor has an absolutely fatal flaw.

As the original designer I should know, and if I had not moved from canada where I had my workshop we would have followed it up with a second design that would correct these flaws. Alas, we never got around to do it and I'm very sorry that didn't happen.

If Nando would have been smart enough to contact me before copying the design I would have gladly helped him to perfect it, but it would have been a little harder to pass it off as his own then :)

Anyway, enough said. As far as I'm concerned that design is not worth building a second one of, there are simply too many things wrong with it.

Best regards,

Jacques

if you feel like discussing the design then feel free to join us on the IRC
www.greenbits.com
[ Parent ]

Re: stator heat again (3.00 / 0) (#9)
by vawtman (vawtman(at)charter(dot)net) on Sat Sep 15th, 2007 at 02:11:07 PM MST
(User Info)

Why IRC and not here?

[ Parent ]

Re: stator heat again (3.00 / 0) (#10)
by jacquesm (j@ww.com- I run a whitelist, add 'stjoes' to msg) on Sat Sep 15th, 2007 at 02:20:11 PM MST
(User Info) http://www.greenbits.com/

because I'm no longer much active on this board but I'm in the IRC 24x7 so that's a more convenient place for me.

Also 'discussion' is a lot easier in IRC than on a message board

cheers

j.
www.greenbits.com
[ Parent ]

Re: stator heat again (3.00 / 0) (#11)
by Nando (nando37-at-tx-dot-rr-dot-com Correct theanti-spam) on Sat Sep 15th, 2007 at 02:58:15 PM MST
(User Info)

JACQUES:
No it is not a clone of your design and I did not design it at all.

Simon, the owner of the 11 KW wind mill, got the drawings from another source and he cut all the materials with a CNC he was upgrading or repairing ( cut the materials for the mill to test the machine) and I helped him to acquire the generator, which was free (not counting the shipping), my part was to teach him how to MPPT the available power.

Centrifugal Pitch Controlled designs are all over the world, I used to have at least 12 - 15 different designs ( this several decades ago), then you could go and search for patents to find many more designs.
Right now there are many more patents and quite a few of them have "died".

I went to your indicated files and saw the build, it looks good.

By the way, I do understand the forces involved and I can calculate them which are needed for a Torque Pitch Controlled Hub, or of course, for a centrifugal pitch controlled hub.

Nando

[ Parent ]

Re: stator heat again (3.00 / 0) (#12)
by Nando (nando37-at-tx-dot-rr-dot-com Correct theanti-spam) on Sat Sep 15th, 2007 at 03:17:55 PM MST
(User Info)

JACQUES:

You failed to read the 11KW and really determine if I did design such centrifugal pitch controlled hub.

Also you run to put down my capacity without knowing if I can or not do such design, I have done 10 and 20 KW Torque Pitch Controlled Hubs and I see that you may have done a centrifugal hub, which did you did not do a Torque Pitch Controlled Hub?.

Since you seem to know the calculations of a centrifugal hub, the calculations of the Torque Pitch Controlled Hub are "close by".

Original designer of the centrifugal pitch controlled died too many years ago, after that, the designs are basic copies of his, many times improved and many times not so improved.

The same thing goes for the Torque Pitch controlled Hub.

Also, I am a design engineer by trade.

Also, the builder seems that was not aware that you existed, so he did not contact you, even more he did not contact me when he started to build his centrifugal controlled hub, when he told me about it and saw what he did, I gave him many more points if we compare yours to mine --.

So please re-direct your put down toward Simon the builder, may be he will respond to your remarks, unhappily, I lost his email address ( cpu crash) to re-direct these messages to him.

Nando

[ Parent ]

Re: stator heat again (3.00 / 0) (#13)
by jacquesm (j@ww.com- I run a whitelist, add 'stjoes' to msg) on Sat Sep 15th, 2007 at 04:13:44 PM MST
(User Info) http://www.greenbits.com/

No, I did read the article, looked at the drawing and my conclusion is simple: no way.

The calculations are 'close by', but the main issues are not. Also, you may want to warn your friend, even if you did conveniently lose his email address (it can't have been much of a collaboration then can it) that his butt welds of the blade boxes are really not the way to connect the blades on a machine as large as this one.

I don't have any beef with 'your friend' 'simon', I have never heard of the man other than through you and you seem to want to paint a picture of great involvement which is shrinking with every posting.

You start off by all but implying that you are actively involved in the building of this machine and now you can't even find the guys email address :) That's a pretty wide definition of friendship...

For everybody that ever considers doing a variable pitch machine, this particular way is NOT the way to go, there is no failsafe mode (even with an added damper, the damper could fail and the design would destroy the tower or itself), if the pitching moment problem will not destroy it first.

I quote you: "I have done 10 and 20 KW Torque Pitch Controlled Hubs" again implies great knowledge, but instead of showing us 'your' design we get the design of your friend. And its fatal flaws of course do not in any way reflect on you because now you had nothing to do with it.

If you're a 'design engineer by trade' and you've done all these great hub designs then why not show your own work instead of the work of other people.

I'm sure that if 'simon' knew he was nearly a full member of fieldlines he'd be happy to join. Heck, all his work is already here anyway, saves him the uploads.

A real engineer would be begging his friend to change the design instead of flying it as it is shown there and worrying about maximum power point tracking. First you make it work reliable, then you start worrying about harvesting the last little bits of power from it.

Real engineers have a code of conduct, and that does not include collaborating on something that anybody with real knowledge in the field would instantly judge to be a flawed design.

Just check the way those blade boxes are connected to the shafts... can you spell fatigue ?

If that thing works for more than 2 years straight you should go and play the lottery with your 'friend' Simon. Assuming of course you can find out again how to reach him.

ciao.

j
www.greenbits.com
[ Parent ]

Re: stator heat again (3.00 / 0) (#20)
by Nando (nando37-at-tx-dot-rr-dot-com Correct theanti-spam) on Sat Sep 15th, 2007 at 11:00:11 PM MST
(User Info)

JACQUES:

Simon did the build and told me after he had the unit built which I complained with many more points than the one you have indicated.

the centrifugal design is not one I would like to build and the desire of presenting a design to a group is not for you to tell me if I do it or not.

There are other reasons that you do not need to know.

I have not recommended this 11 KW design, I presented to the otherpower.com for them to see but suggested that the builder replies to the questioners which he did.

You attack without reason.

First determine why such Torque Pitch Controlled Hub design have not being presented.

Second why do I need (or have to) present or show such design ?.

For one, I have asked DanB ( otherpower.com owner) to build one, and I would assist him to build one -- for about 2 or so years and no takers.

When one tries to contact me for such endeavor TOM W attacks with his vitriole behavior.

Also you assume facts and try to put down my honesty and my code of conduct without knowing the true facts -- THAT IS DISHONESTY FROM YOU .
A real Engineer will determine the facts, not guess them, are you a real engineer ?.

So it is a losing proposition.

Nando

[ Parent ]

Re: stator heat again (3.00 / 0) (#22)
by jacquesm (j@ww.com- I run a whitelist, add 'stjoes' to msg) on Sun Sep 16th, 2007 at 05:46:40 AM MST
(User Info) http://www.greenbits.com/

Hello there Nando,

pot kettle black

I'm not an engineer Nando, also I never claimed I am. But you DO claim you are, you have claimed so publicly and fairly loudly and you use that to elevate the status of the stuff you post here.

You were all but claiming you collaborated on this machine but now it seems you have absolutely nothing to do with it, the machine was already built by the time you ever heard of it.

Then you go and say 'I wonder when one of these expermimenters is going to build a variable pitch machine'

Well guess what, one already did. And there are plenty of people working in that direction, which is more than you can say you are doing. So, you're scoffing at the rest of this board for some reason that I'm not aware off by suggesting that they are not building stuff that is worthy of you, the 'great' Nando whose windmills will one day amaze all of us and HE will be vindicated. The biggest I TOLD YOU SO in the history of fieldlines...

I love the "THERE ARE OTHER REASONS THAT YOU DO NOT NEED TO KNOW". Man, the trump card is out, need to know. I'm sorry Nando, I didn't realize you have access to 'higher powers' that have needs that are not mine... LOL... that's really funny.

You seem to be unable to meet my very simple challenge so from now on you'll be on my 'ignore' list. You are 'able to make designs', 'presenting (I love that word, is that a euphemism for 'copied' ?)', 'able to criticize other peoples designs' and you are 'trying to be associated with other peoples designs' but you are unable to post your own designs or show your own production.

It's funny that you should have to 'assist' DanB in designing a VP mill, the guy has more knowledge of windmills in his little pinky than you do as a whole.

Nice hub nando, I had not seen it. The PDF of tower construction is also quite a find thank you. Pity there is no windmill in there.

So, Nando, put up or shut up. Post a design that you have had a hand in, that actually flew and that actually flew more than a year in one spot. And post a picture of that '11 KW winmdill' that you have been pushing so hard. Or go and build a VP machine and document it.

If not then admit you're a poser and call it a day. I have absolutely no problem with it if you turn out to be just a guy that does a little bit of electronics but stop talking about turbines as if you are Hugh Piggott, you're really too small for those boots. Go and BUILD one of your own designs, document the whole deal and you'll get some serious credit. Until then you're just another armchair windmill builder and a cut & paste artist.

Btw, I've since confirmed make & model of that Chinese mill on the tower in January of this year. I thought it was a scaled up version of the Bergey 1 KW unit, it now turns out it's a scaled down version of their 10 KW version, rated 5 KW but more likely 2.5 to 3.5 in a gale out of an 18' prop.

Torque pitch control is fairly dead, every company that tried it commercially has failed, that should say something.

have a nice day,

Jacques.
www.greenbits.com
[ Parent ]

Re: stator heat again (3.00 / 0) (#14)
by TomW on Sat Sep 15th, 2007 at 04:27:06 PM MST
(User Info)

Nando;

Now is the time to come clean here. Tell the truth and let the chips fall where they may, etc.

Or are there more things you wish to unsay?

Sorry, pal, but you have been busted just as I suspected and its all public now.

Tuck tail and run time has arrived.

Sorry to the rest of the users but this has just gotten to be too much to take lying down.

Lies, half truths and more lies.

Nuff said.

TomW

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

Re: stator heat again (3.00 / 0) (#15)
by jacquesm (j@ww.com- I run a whitelist, add 'stjoes' to msg) on Sat Sep 15th, 2007 at 05:33:03 PM MST
(User Info) http://www.greenbits.com/

Nando, I have some great news for you:

http://www.martinslade.freeserve.co.uk/

is the site that contains the PDF, at the bottom of the page there is a picture
that links to the same stuff that is in 'your' files...

If it was available on the web, you could just as well have linked to it !

Would have saved us all a lot of trouble :) And you would have never lost your friends email address, because, conveniently he has a link to it on his page.

Also there is a picture there of the 'prototype 11 KW machine', but this then
shows a picture of a machine that is nowhere close to 11 kW, but it does seem to sit on the tower that is in the drawings, so there probably is some connection:

http://www.martinslade.freeserve.co.uk/P1010006.JPG

The creation date on that image is

Mon, 22 Jan 2007 21:14:55 GMT

The funny thing is that the tower in the picture is the tower in the PDF, but the hub in the picture (and the size machine quoted) do not match at all.

I can't help but notice that the machine that is sitting on the tower
there if the tower is 9m tall (and it is according to the description)
is only 6 m or about 18' in diameter.

I also can't help but notice that a 10 (or 11 but who is counting) KW machine is roughly 9 m in diameter, and at that size the blades would have some trouble turning because they'd hit the guy wires... Let's hope they added a piece !

if you click the image on the page linked above you land in the pdf.

Which incidentally is pretty useless for comparisons purposes because it expresses the power generated as a function of the rotational speed of the generator shaft, but not as a function of the windspeed...

Do note that the plans mention lots of hydraulics, and that this is NOT a torque hub, but a hydraulically actuated variable pitch machine. So, why do you claim it is meant to be a torque hub ? The two have very little to do with each other.

To help you in your search for your long lost 'friend' I hereby present you with his email address: simon@martinslade.freeserve.co.uk, it was recovered from the CPU you lost at great expense by the CIA using 'carnivore' and express mailed to my door via astral projection. Good to have friends in high places isn't it ?

If that mill ever flew than I'm challenging you to back it up with a picture, I'm sure Simon won't mind you posting one, since you already posted his PDF.

For now all I see is a botched attempt at making a VP hub on the floor of somebody's garage and a cheap chinese knockoff of the 1 KW bergey sitting on a tower that will not support a 10 KW machine because of simple geometry. Please prove me wrong, it would make my day. To see that machine in person would make my day even more but I think that as long as the blades are going to be attached the way the photos show that I'll decline for now.

Also, I would like to remind you that passing yourself off as an engineer when you are not (and we are talking licensed engineers here, or is a design engineer somehow exempt) is very unwise.

best regards,

Jacques
www.greenbits.com
[ Parent ]

Re: stator heat again (3.00 / 0) (#5)
by Dave B on Sat Sep 15th, 2007 at 11:37:31 AM MST
(User Info) http://www.madbbs.com/users/bruggelog

Pepa,
It would work I'm sure but why not just decide what maximum continuous output you require and design for it from the start ? Now that so many 10 and 12 foot axial machines have been built using the common coils / magnet set-up it would seem to me that a maximum (continuous) output has pretty much been establised for that particular design ? The Dans could shed some light on this I'm sure. The dual rotor axial design is great, any stator will burn up if it's max. continuous output is exceeded. That's the key (continuous). Because the wind speed varies so much we usually "see" peak outputs and from this call the machine a 1000 watt machine or a 2000 watt machine etc. etc. It's hard to accept that a "1000 watt" machine could possibly burn up at a continuous 1000 watts or even less. Just throwing numbers out there but I think that could be what's happening when we see some of these stator fatalities. Accept a safe continuous output by being fully furled at that level no matter what size machine. It's not a question of "if" your machine will be pushed to it's limits, it's when. Dave B.

Re: stator heat again (3.00 / 0) (#17)
by pepa on Sat Sep 15th, 2007 at 08:18:10 PM MST
(User Info)

thanks Dave for the reply, i have built several of the 10' machines and one 17' and followed Dans instructions to the letter. i started thinking about stater heat after his first burnout, and thank goodness, so far i have not had any problens with any of my mills. this was something i though might work and if i used some of the reclamed wire from my microwave coils, it would not be any extra cost involved. i live on the coast and have average winds of 7-10 mps, but a lot of strong storms with wind of 50-80 mps when a front comes through. i build for light wind and furl at 25 mps but have seen max wats at a full furl and it is a frighting thing to watch, if i built for high wind i would miss most of the wind. the 17' is flying at my hunting lodge and there is no one to shut it down when needed. just something to thank about, pepa.

[ Parent ]

Re: stator heat again (3.00 / 0) (#25)
by Dave B on Sun Sep 16th, 2007 at 06:52:59 PM MST
(User Info) http://www.madbbs.com/users/bruggelog

Pepa,
I had my previous machine over speed which the main reason was I did not build in enough offset for safe furling. It is scarey for sure as I measured slightly over 800 RPM for my 12' diameter blade in 60+ MPH winds. If the furling is set to max. furl at what has been measured to be "peak" outputs in high winds then this can spell trouble when the sustained winds happen at these speeds. All the black magic seems to happen right there where wind seeking force, gyroscopic forces, centrifigal and centripital forces (sounds technical any way) can do some weird things if the furling is set a little "too hot" from ideal. I am no expert but my observation has been that if things aren't quite right which includes the load seen by the mill that higher RPM than wanted can happen at times for too long even when very nearly fully furled, burn out. I think the gravity furling tail is simple, effective and a brilliant design to dump wind and limit speed. We seem to get away with peak outputs in gusty winds but can see burn outs even below these peaks when the winds are constant long enough and fully furled is set too high. We all know those winds will happen. Like you know, until you've been there it's hard to appreciate how helpless you feel. Keep us posted of your designs, safe is good. Dave B.

[ Parent ]

Re: stator heat again (3.00 / 0) (#16)
by jacquesm (j@ww.com- I run a whitelist, add 'stjoes' to msg) on Sat Sep 15th, 2007 at 06:13:20 PM MST
(User Info) http://www.greenbits.com/

hi there Pepa,

Sorry for hijacking your thread... It was not intentional but I got a little inflamed :) My bs meter went right into overdrive on seeing that PDF that you referred to, note that the date at the top (the date of the pdf) says 12/12/05 but that same tower shows a 1 ... 2 KW chinese (or somesuch) mill on the 22nd of January 2007.

Makes you wonder what happened in the meantime to the 'prototype'. It sure wasn't on that tower when nando posted his 'find'. I always get this feeling when I see windmill parts, towers, power curves that are fantastic but no actual windmills. My bs meter shoots right into the red :) Add to that a complete misinterpretation of the design as shown in the PDF and I'm pretty sure that all is not what it seems. The author of the PDF specifically mentions hydraulic control coming down
the tower in addition to power lines but you don't need hydraulic control for a torque controlled hub. Maybe they are for the brakes ? Then there is the case of the wrongly positioned pillow blocks, they're too close to the front, the first storm will take them blades included... But of course, that's only a drawing. I think that if you put together a PDF of a prototype windmill it should have at least one picture in it of the working windmill. This is a pdf about tower construction that as an afterthought mentions how you can weld together a VP hub. It does not show a working machine.

About your idea: it's pretty clever and I have not heard about it before or seen something like that (but that doesn't say much). You are basically dynamically changing the resistance of your coils on demand and air cooling those resistors at the same time.

The problem is the added complexity this adds, and the problems of having relays switching on and off on top of your tower are compounded by the effects of aging and the weather.

It's an interesting idea though, I would suggest a relay with a large hysteresis to avoid it switching on too fast again after switching off, better to keep the number of cycles down. And if you can use solid state relays, they age a lot better than mechanical ones.

And please post your experiences, even if it fails we'll all learn something new.

As for variable pitch, it is by far the best way to build a mill (I think) but I have yet to see a design that is simple enough and reliable enough to be executed by just anybody manufacturing or ordering a bunch of parts and bolting it together.

I'm sure that one day it will happen though, but I doubt it will be a 'budget' machine. VP has it's own unique set of problems (no matter what the control mechanism), and the control mechanisms are subject to all kinds of problems all by themselves.

best regards,

Jacques.

www.greenbits.com

Re: stator heat again (3.00 / 0) (#18)
by pepa on Sat Sep 15th, 2007 at 08:44:34 PM MST
(User Info)

hello Jacques, i like your greenbits site. i was thinking of using a motor over heat switch and it would only release the extra coils when the regular coils cooled down to a safe working temp. i have also been working on a pitch control design but nothing put togather yet, soon i hope. one uses a stepper motor in the hub to activate the pitch and one that uses the weight of the blades. to much thinking and not enough doing, pepa

[ Parent ]

Re: stator heat again (3.00 / 0) (#21)
by jacquesm (j@ww.com- I run a whitelist, add 'stjoes' to msg) on Sun Sep 16th, 2007 at 05:27:31 AM MST
(User Info) http://www.greenbits.com/

make sure it fails 'safe', every component can break and you have to analyze the system with that component broken it should automatically feather the prop. I think that's the hard part in VP designs.
www.greenbits.com
[ Parent ]

stator heat again | 27 comments (27 topical, 0 editorial)

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