Ferrite Gen with a Classic 150

[SparWeb]

Normally the maximum temperature of a winding is limited by the class of insulation. Given suitable materials elsewhere that ultimately means a limit on the wire coating.
Normally I wouldn't see any limit on current as long as that wire coating temperature is not exceeded but your information seems to imply that there is a practical limit even when the wire coating temperature is not reached.
....
Relating this to what a wire can carry in a winding is rather different except for short term rated machines. With these type stators the limiting temperature is reached on the wire at the centre of the coil where heat can't get away easily. Stator thickness is a big factor here even if there is air cooling over the surface, the centre turns will be much hotter than those near the surface.
Flux

This could be a case where the rate of temperature change is important.  By that I mean that the copper expands due to heat, and copper is an excellent heat conductor mind you.  At the same moment, the insulation varnish hasn't had time to reach the same temperature, and I might add that electrical insulators are poor heat conductors, too.  The exterior of the wire insulation is in contact with an insulator, too, also a factor in the heat gradient relationship. 

The end result is a series of interfaces between materials with different thermal conductive and thermal expansion rates, which can lead to shear stress cracks in the bonds.  In cases where the differences build up slowly, there may be fewer problems than in cases where the gradient changes rapidly, and repeatedly, causing fatigue cracks (borrowing the phrase) in the insulation that will lead to its breakdown.  I thought I read about this but I can't remember where, now.

Okay all high and dry, and I think at this point Chris wants to step in and say "enough speculation".  Since he's gonna try it on his dyno anyway, we'll all just see what kind of heat-buildup there is when he runs it.  Looking forward to it, Chris.

[ChrisOlson]

Okay all high and dry, and I think at this point Chris wants to step in and say "enough speculation".

Actually not.  I think it's all good speculation because the properties of wire are a mystery to me.   
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Chris

[ChrisOlson]

My New Year's Eve project - finished building the basic frame for my new 3.2 meter turbine



All I have left is to weld the tail feather brackets on and build the cover for the gearcase.  Then it's ready for paint and final assembly.

It's cold, stiff 30 mph wind out of the NW, and snow coming down so thick I can't see from the shop to the house.  So the shop seemed like a good place to be.  This turbine ended up a team project because my lovely wife even came out to the shop and helped hold pieces for the tail assy while I tacked 'em up   

Happy New Year's Everybody!!
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Chris

[ChrisOlson]

Well, I ended up building the tail way too light.  I calculate that I need at least 18 lbs of tail tip weight to get this machine to 2.5 kW @ 12 m/s with an 18 degree hinge.  The tip weight ended up at 9 lbs with a Lexan feather on it.  Rather than putting on a heavier feather I put a 10 lb weight out at the end of the tail.



I would've liked to use a vertical hinge with a spring loaded furling control.  But the extra brackets to mount that type of tail and provide clearance for the generator stator and rear rotor would've gotten the CG too far back on the yaw.  The bare frame, as it is, weighs close to 100 lbs and I need 60% of that ahead of the yaw axis so it's balanced properly on the tower when the rotor is under load.

This little 3.2 meter turbine is still going to end up over 200 lbs.
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Chris

[jarrod9155]

For future tails think of using curagated alumiun board , sign shops use it for sign backs  very light and real strong used it on my new machine to shed weight .

[TomW]

For future tails think of using curagated alumiun board , sign shops use it for sign backs  very light and real strong used it on my new machine to shed weight .

My 9 footer uses a hunk of 3/16" solid PVC sign board. Been a couple years I guess. So far so good but is a tad light.

I tried some of that corrugated looks like cardboard with wavy center and flat outer sheets plastic sign board stuff but it tore thru at the fasteners.

Just ,my experience.

Tom

[ChrisOlson]

I'm not so much concerned about the total weight as much as where the weight is distributed on the machine's yaw.  The bigger machines with dual stator gens are quite tail heavy and that's hard on the yaw bearing long term.  I was hoping to get the weight more forward on this one.  It is more forward, but not as much as i'd hoped.  I have to weigh the rotor (I think it's around 45 lbs) so I can figure out where the actual CG is.  But that 10 lb weight back there on the tail didn't help.

With a vertical hinge and spring loaded furling control I could use a much lighter tail.  But having the hinge too far back from the yaw also causes a CG problem during furling - and also a problem with aerodynamic drag on the tail trying to pull the rotor back into the wind with quite a mechanical advantage on the yaw with the long lever provided by having the hinge located a long ways from the yaw.  So the further the hinge is moved back, the more forward "lead" is required on the rotor to counteract the tail torque on the yaw shaft during furling.

So I dunno.  After I weigh the rotor so I can figure out the torque moments, I'll have a better idea if this is going to work OK this way.
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Chris

[ChrisOlson]

I got my new machine ready to assemble with the bare frame on the stand and a pile of parts on the bench.  Right now, it looks sort of like a bird house with a tail on it   





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Chris

[fabricator]

Yikes! I'll bet tractor supply likes to see you come in the door.

[ChrisOlson]

Yeah.  There's a lot more little pieces than one realizes when you start putting a transmission together.

I test assemble sub-components and make sure everything fits and meets tolerances, and if it does I throw the parts in that pile for final assembly.  The pile keeps growing by the time I'm done checking everything for tolerance, but everything in that pile goes in that transmission   

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Chris

[ChrisOlson]

Movies!

http://www.youtube.com/user/OlsonFarms?feature=mhee#p/a/u/0/9hR_Kc-nJPI

It works!
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Chris

Note to all the guys that have emailed me about building ferrite turbines - I will answer when I get caught up a bit and get this machine ready to go on the tower.

[vawtwindy]

^{when I get caught up a bit and get this machine ready to go on the tower.}

i will be waiting for that moment.

[jarrod9155]

Cool video , I was wondering have you had any problems with water on the outside of the bearings . I put some rubber seals on the end of the shafts were the face of the bearing is exposed . You have a little more experience with these bearings are seals a good idea or not needed , they do cause a little drag . I used 3.5 rubber sewer caps and drilled out the center to the proper diameter .
     Thanks Jarrod

[bj]

    Thanks for the vid Chris.  Also always nice to see the person involved.  Kind of like actually meeting you.
    I know that I would recognize Ghurd's big toe anywhere now,

[ChrisOlson]

Cool video , I was wondering have you had any problems with water on the outside of the bearings

No.  Those bearings will not let water in.  You can pressure wash them at 1,500 psi and they won't let water in - I do it all the time on equipment that uses the same bearings.  These bearings, unlike the chincy tapered roller bearings and lip seals used on trailer spindles, are designed specifically for severe duty applications where the bearing spends its entire life running in dust, dirt and water.

On the mainshaft I used SKF extended race angular contact ball bearings (expensive - $47 each - and rated for both high axial and radial loading).  The PTO shaft has normal SKF ball bearings rated for high radial load and 50% of the max radial load on axial loads.

People get all excited about "drag" in wind turbine bearings - some even go to the extreme of leaving the seal out of tapered roller bearing sets on turbines built with trailer spindles because they're worried about the "drag".  This is pretty ridiculous and here's the facts:

The rotating torque with  new set of bearings in this transmission is 8 lb-inches.  At 100 input rpm that's .013 hp or 9.7 watts required to turn the geartrain.  At 200 rpm - .026 hp, or 19.4 watts required to turn the gear train.  At 400 input rpm the geartrain absorbs roughly 40 watts.  It takes about 100 hours of break-in time on these units and the rotating torque drops to around 3-4 lb-inches.

But even with a new machine, if you're worried about 8 lb-inches of torque to turn the machine, then you're building hobby turbines that don't make any power anyway and you may as well leave the grease out of the bearings too because that causes "drag".  If you don't have enough wind to overcome 8 lb-inches of startup torque on a 3 meter machine, then you're wasting your time building a wind turbine in the first place.
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Chris

[jarrod9155]

The drag is the least of my worries , things like bearing failing and chewing a stator and losing control of  the turbine then blades hitting the tower and then taking down the whole thing  just because water caused premature failure . I guess I'm still worried from my last turbine  with trailer hubs . Thanks for the input  , the new beast is set to go up this  weekend with the new generator . After the first 2 months with the 20 foot blades so far no sign at all of bearing play or movement of the shaft .
Thanks
     Jarrod

[ChrisOlson]

No - ball bearings do not go out of adjustment.  They just run.  They run with less friction than tapered roller bearings, they never require adjustment, and when one does fail it will start making noise and give ample warning long before it will stop turning.  And when it does fail it will just seize up without your generator hitting the stator.  When ball bearings fail the cage disintegrates and the bearing "piles up" internally and seizes.

On machines where ball bearings are used for shaft support, and the machine has adequate shaft torque to turn an otherwise seized bearing, you can get the ground up balls to disintegrate and the bearing will go race-on-race.  But there's no wind turbine I've ever seen that has enough torque to do that.  Even a small 1" bore bearing takes several hundred lb-ft of torque to turn it when it's seized.  The bigger the bearing, the more torque it takes to turn it in a seized condition.  On a 20 foot turbine with 1.75" bearings, that can maybe develop 400 lb-ft of torque @ 200 rpm, it will just grind to a halt when a bearing seizes up.

Tapered roller bearings fail BECAUSE of improper adjustment, assuming they have adequate lubrication.  Oil bath tapered roller bearings must run preloaded or they will fail.  Grease lubed tapered roller bearings must run with zero preload/endplay to slight end play or they will fail.  There's a reason the auto-makers have gone away from them in wheel bearing applications and they now use cartridge bearings.  Those grease lubed tapered roller bearings used to be a 100,000 mile maintenance item, and a wind turbine puts that on a set of bearings in the matter of a year.
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Chris

[SparWeb]

It comes to life now with the video, Chris.  Two criticizms, though:

Your Chevy is too clean,

Too much Def Leppard.

[halfcrazy]

It comes to life now with the video, Chris.  Two criticizms, though:

Your Chevy is too clean,

Too much Def Leppard.

Its a Dodge Cummins I do believe and if it is like mine it rattles all the dirt off

[ChrisOlson]

Your Chevy is too clean,

Chevy?  CHEVY?  What sort of blasphemy speaketh you?

Them Chevy pickups with their toy aluminum-headed Jap diesels and automatic transmissions are what we call around these parts, "as worthless as tits on a boar pig".

That's a Ram 3500 with Cummins power, a NV5600 Spicer 6-speed and Dana/Spicer M80 military axles.  Ain't none of that week kneed independent front suspension BS with chincy half-a$$ shafts driving the front wheels on that truck.  If you don't have enough solid iron under your truck to drive over stumps with it out in the woods without bending stuff up, it ain't worth having.   
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Chris

[TomW]

  If you don't have enough solid iron under your truck to drive over stumps with it out in the woods without bending stuff up, it ain't worth having.   
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Chris

Haha, always knew you were a ridge running stump jumper. 

Tom

[ChrisOlson]

Haha, always knew you were a ridge running stump jumper. 

Or worse.   
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Chris

[bob golding]

Movies!

http://www.youtube.com/user/OlsonFarms?feature=mhee#p/a/u/0/9hR_Kc-nJPI

It works!
--
Chris

Note to all the guys that have emailed me about building ferrite turbines - I will answer when I get caught up a bit and get this machine ready to go on the tower.

nice vid Chris thanks. wish i had he facilities and skill to do something like that. my efforts work but are not pretty. got a fully charged set of batteries here after a week of 60/80 mph gales, and it is still producing power so can't complain. with the reduced number of magnets it is not slowing down when it furls  but it is staying together so far.
 still cutting up bits of core for the ferrite design, will post progress when something interesting happens. don't think me and a pair of tin snips  would be all  that interesting somehow.

[ChrisOlson]

Here's a photo of how how the rotors are installed on these machines.  Using a hub puller is much safer and simpler than them confounded jack screws.  Although I have to standardize stuff.  I've built some gens with 5/16" puller holes and some with 3/8".  Seems to be a deal that involves what size tap I grab out of the tap and die set.  This one's got 3/8" holes in it



I really like this method of mounting the stator too.  With the steel bushings pressed into the stator, I crank them 1/2" bolts down to 65 lb-ft of torque without splitting, crushing or cracking the stator - and it will never come loose.  Plus it's 10x stronger than threaded rod.  You can beat on that stator mount with a maul and can't change it's position - I know because I tried it after I welded it up because it was off a bit.  I ended up having to adjust the length of the mounting bushings to make the stator perfectly square with the rotors, and welded the mounting bushings to the stator support so they don't get mixed up.



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Chris

[ChrisOlson]

Well, I made another sit-on-the-edge-of-your-seat nail biter:

http://www.youtube.com/user/OlsonFarms?feature=mhee#p/a/u/0/-9JPFvoEcgI

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Chris

[SparWeb]

Here I was thinking that the Def Lep comment was more likely to get a rise outa you...

A better choice of music we can agree on:

http://www.youtube.com/watch?v=pDY6bWT5oTM

[ChrisOlson]

Here I was thinking that the Def Lep comment was more likely to get a rise outa you...

Oh - well......  I guess I always listen to that one radio station, and I've grown to sort of like it.

I can't listen to any other radio station because the radio is broke.  My wife used to have that radio in the kitchen on the counter and one day when she was cleaning, or whatever it is she does in there when I'm not watching, she busted the tuning slider off it.  So she came carrying it to me and asked me if I could fix it.  She handed me the knob - it's a plastic chrome thing with a long arm on it that must attach to something in there.

I told her that it cant' be fixed - it's junk.  So she left it in the shop and went and bought a new one.  I plugged it in and wouldn't you know it's permanently tuned to Fox 99.1 Classic Rock.  So now I listen to Bon Jovi, Frampton, Def Lepard, Van Halen - they even had Sammy Hagar on there the other day with "I can't drive 55"!  I used to drink a lot of beer listening to those songs in college, man!
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Chris

[bob golding]

i was cringing a it when you were leaning on the rotor with your fingers inside it

[dsmith1427]

Great videos.  Thanks for posting.

Good music but I also like Sparweb's choice... everybody should listen to Corb Lund and the hurtin albertens... it's entertaining, very entertaining. 

[ChrisOlson]

i was cringing a it when you were leaning on the rotor with your fingers inside it

Yeah, I should point out for folks who might built a ferrite generator that there's as much attraction force between those rotors as there is with a neo of the same power.  Especially with those big 1" thick ferrite blocks.  They're easier and safer to handle when installing them on the rotors and stuff.  But when you got 32 of them on two 16 pole rotors they will slam together just like a neo will.

I shimmed the generator to 4.32 input shaft rpm per volt from the gen.  That will let the rotor spin at ~6.5 TSR thru much of the power curve instead of 6.0, at the same input voltage to the controller that I tested it with.  I decided to do that because the blades I'm using like to run at a bit faster than 6 TSR for best efficiency.  Running the blades a bit faster, I might be able to squeeze 2.5 kW out of the thing right at 12 m/s with the gen only putting out 28 amps and it should hit 1 kW @ 9 m/s.

I could've probably put a few less turns in it, but it's still ~85% calculated gen efficiency at 2.5 kW, so I'm not too worried about it.

Having a little leeway in the gen will also allow me to put a set of GOE222's on the machine and run the rotor a bit slower, if I want.  I'm going to test it with the higher speed S809's first and see what it does.  Typically, the GOE222's are better for lower wind speeds because they got more torque and come up to speed faster.  And they don't lose speed with increase in loading as fast as the high speed airfoils do.  The kWh meter will tell the story on that experiment.
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Chris

[ChrisOlson]

We getting close.  Real close.







The trailing edge of the airfoils clears the front of the gearcase by about an inch.  I mounted the front PTO bearing flush with the case anyhow






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Chris

[Volvo farmer]

Are those homebrew blades or some variation of those windmax things?

[ChrisOlson]

Are those homebrew blades or some variation of those windmax things?

They are neither.  They are S809's - fiberglass blades - used on the Talon downwinders built by A&C Green Energy in Dallas, Texas.
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Chris