What's the latest on the 17' Diameter on home page

[gator]

I'm itching at the bit to learn more details about how the 17'diameter wind tubine listed as an acive project on the wind home page is lasting and any improvements or plans for it.  What would it take to replicate into 24 volt vs. 48 volt.  What improvements should be made before attempting a simular project.  BTW- This site is cool!

[DanB]

I should update that page with some suggested improvements...

The machine has had two failures since we put it up about 1 year ago.

First, I had not provided enough clearance between the blades and the tower.  About 3 weeks after raising it the blades struck the tower.  I cut the alternator loose and tipped it back a couple more deg.  We epoxied the blades back together and they've been fine ever since.  That story is here: http://www.fieldlines.com/story/2005/2/22/63454/0111

Then we got struck by lightning last summer, and one of the rectifiers blew such that 48V was running back through the line into the stator.  We figured that out when the machine wasnt turning - and smoke was coming from the stator at the tower top.  (it cooked for about 10 min).  The stator was OK, but slightly warped so I was able to adjust it's position between the magnet rotors and it's been OK ever since.  (the adjustment has gotten very touchy now though as the stator is a bit like a potato chip)

Other than those things there have been no problems except for one tower failure which was not the fault of the machine itself.

To do it over I'd probably use slightly bigger magnet rotors, a slightly bigger wheel hub with larger bearings, and a stronger (more rigid) stator bracket - but as it is it's OK for now.  I hope it stays that way because we really depend on that machine these days, without it I'd be burning tons of diesel.

[Gary D]

Dan, to change from a 48 volt system to a 24 machine, would he need to have double the same gauge wires per coil and 1/2 the turns for the same rpm's output? And double the rectifier current capablilty with twice the heatsink? If my puny brain is working at all today...

Down the tower wire gauge and the run to the battery bank would need upgraded also? Hope this doesn't seem too stupid. Someone please stomp on me if I've overstepped the boundries!   Gary D.

[Waterfront]

I'm thinking the same thing...

Your brain was fonctionning in the «on» position, hehe...

[theTinker]

danb,

any homebuilt machine that stands up to lighting bolt of a zillion volts must make the creator very proud, lighting bolts are the biggest test i think u could have.

[gator]

Well, you built one heck of a machine!  The comments by Gary D. about converting to 24 volts seem reasonable.  What are your thoughts.  I'm assuming the rectifiers would be available but not sure.  As far as heat sinks, the back side of RV refrigerators have nice ones made of aluminum and they are huge and look like they would be very effective.  That was my plan.  Your picture of the stator brackets did make me think of needing something a little more even before your comment here and I am not lacking in 3/8" plate steel so I'll probably use some of that.  I live on top of a hill here in texas and have that's flat about 200' on top where my house is that I built from scratch with slopes to the south and north.  With the wind being pushed up these slopes I'm wondering if I tower too high will I loose the wind accelaration and compression.  I'm in the market for an anemometer to raise and lower from ground to about 55 ft.  The 24 volt idea was due to the abundance of inverters for reasonable prices.  I could build a 10 ft machine or 17 ft.  With 6.5 acres might as well go for gold.  No sweat off my back.  Cheers,  John

[gator]

One more thing Dan.  Can you put some protection in line with each of the phases?  Maybe some circuit breakers or huge diodes or something.  I am not an electronics man. I know enough just to keep from getting electrocuted (although I do know what a resistor, capacitor and diode are but I wouldn't know how to size them). Your machine is a great "model" for us that in my opinion ought to be continually explored and replicated.  This is a lot of power you are making if utilized wisely. I used to hate the wind in the winter but now hate the fact that it is going to waste waiting on my wind machine.  Tower design is what I'm working on now till I'm clear on what I'm building through these post.  Cheers again, John

[gator]

The aluminum heat sink inside the RV refrigerator is what I meant to say.

[DanB]

Even as it is, the windings are pretty thick - I forget how many strands I used in hand, but I think itll start getting tricky at 24 V.  You could do it certainly - although Im not sure I'd compromise they system over the price of inverters.  That will be a very small part of the over all cost.  The money you save on an inverter will probably go away when you figure that you'll need a bigger charge controller (something able to dump 150 amps @ 24 V) - more rectifiers, heavier line etc..

If you dont have a system yet - I'd go straight for 48V.

[DanB]

Yes - after reveiwing the page...  he'd need to wind each coil w/4 strands of #15 gage wire in hand, 34 windings per coil.

In the long run - all things considered, I expect a 24V system with this machine will cost more and be less efficient than a 48V system, the only savings would be perhaps inverter cost and I would say that the less expensive 24V inverter is probably not as good an inverter as the more expensive 48V unit.

[gator]

I'm convinced on the 48 volt.  Now I'm ready to start ordering magnets and wire.  I can have the plate steel laser cut locally after I purchase the hub and spindle (I'll go with your suggestion on one a little larger) also local.  Dan you commented on larger diameter rotors.  I would suspect it wouldn't need to be much larger.  In reading about your 17 ft machine you ended up with about 3/8 gap at the lower end of the magnets.  What would you have preferred?  1/2 inch? 5/8 inch? Or was it that the coils from the stator were packed too tight to suit you? From this I could calculate the diameter of the rotor.  Any other tips on replicating your 17 footer will be helpful.  I did read about your blades hitting the tower. How do I determine what is enough angle and what is too much?  It's hard to take a wag at a picture.  Oops, but good the blades where that flexible, a testiment to good cedar laminated blades.  I'll try to keep a good photo log book as I go along and spread the good news to my friends and neighbors albeit I own the hill...FYI, even though we get good winds I want a low wind performer such that the 17' will produce and provide adequate power for my office and a few outside florescents and expand from there.  Mostly this is for fun...and hopefully helps in retirement, if I make it.  Thanks for being an icon in home brew wind electricity.  Cheers,  John

[DanB]

Hi caseyjt -

"I'm convinced on the 48 volt."

I don't think you'll regret that in the long run.  A system is fairly expensive it $$ and time, the cost of the inverter is a very small part of it.  Plus - if you get a good inverter it'll most likely contain a powerful charger which is nice.

"I can have the plate steel laser cut locally after I purchase the hub and spindle (I'll go with your suggestion on one a little larger) also local.  Dan you commented on larger diameter rotors.  I would suspect it wouldn't need to be much larger.  In reading about your 17 ft machine you ended up with about 3/8 gap at the lower end of the magnets.  What would you have preferred?  1/2 inch? 5/8 inch?"

I wouldn't change things too much only because I know this combination of things works.   But a bit larger would help - not just because the magnets are too crowded, but also it'll allow for a larger hole in teh stator.  As mine was, the coils are of such size that they come very close to the hub.  I would advise a larger spindle/hub - and youll want more room in the stator to accomodate that.

"  Any other tips on replicating your 17 footer will be helpful.  I did read about your blades hitting the tower. How do I determine what is enough angle and what is too much?"

5 degress would be plenty.

  "It's hard to take a wag at a picture.  Oops, but good the blades where that flexible, a testiment to good cedar laminated blades.  "

"The blades are holding up real well - and we've had lots of violent wind up here latetelty. I'll try to keep a good photo log book as I go along and spread the good news to my friends and neighbors albeit I own the hill...FYI, even though we get good winds I want a low wind performer such that the 17' will produce and provide adequate power for my office and a few outside florescents and expand from there.  Mostly this is for fun...and hopefully helps in retirement, if I make it."

Good - it's a good way to go into this 'for fun' - because it's not always cost effective compared to grid power.

I'll post more on this later in the week - but..  I took my machine down today because a weld broke in the tower.  We fixed the tower , but the machine itself has problems.  The bearing has loosened somewhat (bigger spindle and hub I should've used).  In a large diameter axial machine with the airgap tight - a bit of bearing play can trash the stator pretty easily.

Also - the way I cast the magnets in this one isn't going to work out.  Some of the resin has broken and there are loose bits between some of the magnets (making a funny sound every time it goes round which I've noticed lately).  Some of that resin has hit the stator and rubbed it through to copper in 1 spot.  A couple of the magnets have broke loose and moved out about 1/4".

Basicly Monday we'll overhaul this machine and hopefully you can learn from my mistakes!  It's been good for a year - but I expect if we dont fix it up it wouldn't last another month without trashing the stator.

[dinges]

Very interesting indeed. Guess you're running into some scaleability problems with the design. And I see you guys are still way ahead of the rest of us Low technology, but still cutting edge (what does it say about the rest of us; not even at the cutting edge of LOW technology... OMG!)

Looking forward to the updates!

Peter,

The Netherlands.

[hvirtane]

Basically Monday we'll overhaul this machine and hopefully you can learn from my mistakes! It's been good for a year - but I expect if we don't fix it up it wouldn't last another month without trashing the stator.

I hope that you will post a good

picture story of the overhaul.

Do you have any idea, why some magnets

got loose?

- Hannu

[wdyasq]

Dan,

I'll take this time to get on my epoxy rant and also state I think a good bit of roving like used in 'chopper guns' but left uncut could be put in the stator to good effect.  This would increase strength and epoxy should bond to more than polyester.

I hate to spend money.  I hate to spend more money and time and redeaux stuff I should have done different when I 'thought' better.  You might try and find some MAS epoxy.  It is a lot more gentle than WEST system I ahve been told.

Ron

[DanB]

Hi Ron - I probably will recast the magnet rotors in epoxy this time - hard to say, I dont have any on hand and Im dying to get this back up tomorrow if possible, but well see.

The stator is not a problem, but I agree -  what you suggest would strengthen it.  I expect the stator here is fine, it's the magnet rotors that need attention.  I may have to hold out for some epoxy on this project - Im just fearful that it might snow before I get the machine raised again... that could be bad as I really need the power.  One good snow storm could keep it down for a long time.

[Cjohs]

Nice to hear the news on that machine.

I am curious about the electrical setup behind that 48V 3800W peak performance rating (I couldn't find much information about this in your webpages), as I am in the process of planning a similar system at my house in Denmark (Scandinavia):

• How are your batteries wired (4 in series?) using a off-the-shelf or DIY charge-controller?
  
• what about dump-loads? You must be able to "get rid off" those 3800 watts of energy.
  
• Do you have inverters to handle all that power?
  
  

As I a live in a place where the grid-power is 230VAC I am looking into inverters for this purpose and have not seen any of this magnitude for our voltage.

Greetings from Denmark

Carsten Johannesen

[Gary D]

Greetings from America. Outback e series inverters can be "stacked" to give you more watts output(recommend you check local sources). It doesn't seem at this time that trace inverters can do what you want, although if  powering completely separate power panels (breaker boxes)you could. I think Dan B.'s machine has hit over 5000 watts during super high winds. So you may need to dump lots of power in a hurry once your batteries are full.   Gary D.

[Cjohs]

Thanks for your reply. I must look into those outback converters - the selection of inverters here in denmark is pretty modest - at least if your a regular person (business to business I don't know about).

I've read Hugh Piggotts book and he suggests some kind of cascading dump loads where you have multiple dump loads that cut in gradually (as they are needed). This might be the way to go if I can't find a BIG converter or stackable converters for an affordable price. But then I would have to build some electronics to control this. Hmmmm no easy way to "free" energy I guess ;-)

How big a battery "park" does the 17' charge into?

What I would really like to see on the webpages is a description of the design and implementation of the electrical side of the windmill installation. With pictures and design considerations, just as with the pages about the construction of the windmills. I would imagine that the visitors (like me ;-) would find this at least as interesting as your current pages.