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Forum Index : Windmills : Another Ferrite Gen
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ChrisOlson Regular Member  Joined: 19/01/2010 Location: United StatesPosts: 60 |
Some of the guys here may have seen this on the Fieldlines forum. But for those that haven't I decided to post it here too as there's not much being done with ferrite mags these days. I'm building a new machine with a 3.2 meter rotor driving a geared three-phase ferrite axial gen designed to run at 100 volts on a 24 volt system with a Midnite Solar Classic 150 MPPT controller. This is a few photos of the project. I built a new gearbox and head for it. This gearbox has a .400:1 ratio (2.5x overdrive) 
This is the blades I'm using on it - these are glass blades with a S809 airfoil 
The gen is 16 pole using 51 x 51 x 25 mm thick C5 ferrites on 355 mm rotors - in this photo I was checking the balance of the rotor on my test turbine head by running it up to about 2,000 rpm. The gen will cut in at 250 rpm (100 rotor rpm) and reach 117 open volts @ 1,000 rpm (400 rotor rpm). 
This is a couple photos of the stator for it - 12 coils, 45 turns of 13 AWG wire, .55 ohm internal resistance, wired wye 
At 100 loaded volts to the controller @ 1,000 rpm (TSR 5.6 @ 12 m/s) the generator will develop 3 kW ([117-100]/.55 = 30 amps) @ 85.8% efficiency. -- Chris off-grid in Northern Wisconsin, USA |
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| charlie_ruizpr Newbie  Joined: 08/07/2010 Location: Posts: 36 |
keep us updated, very nice |
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| VK4AYQ Guru  Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Chris Thank you for the post, it is very encouraging as I am preparing to have a go with some ferro magnets, I picked up a set of 2x3x1 blocks last week. Kindly supplied by Phill Mann at OZ AX engineering along with a set of GEO 222 blades and a set ofslip rings, all very nice quality products. All the best Bob Foolin Around |
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mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Greetings Cris, Thanks for posting this info...its very impresive for ferrite magnets and gives you'r geared concept lots of credit in its ability. I've been following you'r builds with great interest. I'm also just starting on a generator somewhat simular for my large vawt and useing the very same size magnets. I can't build these things in record time like you however. Thank you again for the info and picture posts, keep us up dated. Regards, Mac46 I'm just a farmer |
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| ChrisOlson Regular Member Joined: 19/01/2010 Location: United StatesPosts: 60 |
Well, I got the head test assembled and the stator clamped firmly between the gen rotors so I can build a stator support for it 
-- Chris off-grid in Northern Wisconsin, USA |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Greetings again Cris, Very nice work...the pictures are indeed worth a thousand words. I'm trying to picture in my mind what a 3 foot diameter rotor like that would look like. I just picked up more 1/4" and 3/8" plate today, it does'nt take much of that stuff to make a good load in the pickup. Thank you for the post. Regards, Mac46 I'm just a farmer |
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| govertical Guru Joined: 11/12/2008 Location: United StatesPosts: 383 |
Hi, what is the load used at 100 volts? Is there a way to determine the current when using a 12 volt deep cell as a load? I am still learning and any help is greatly appreciated. I look forward to seeing the stator mount. Do you have any photos of the gears? just because your a GURU or forum administer does not mean your always correct :) |
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Racingken Newbie Joined: 24/11/2011 Location: United StatesPosts: 28 |
Nice looking work there Chris! I will need to get myself a few tools, such as a Drill press and maybe a lathe if I can find a good used one. I have no way to cut my own steel for my parts, so I will need to think of other ways to get by. I do have a friend that is a great welder tho. Mac I can tell from your wording you meant 3 meters and not foot. Ken Racingken |
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| charlie_ruizpr Newbie Joined: 08/07/2010 Location: Posts: 36 |
What is the output on this beast. |
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| ChrisOlson Regular Member Joined: 19/01/2010 Location: United StatesPosts: 60 |
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| ChrisOlson Regular Member Joined: 19/01/2010 Location: United StatesPosts: 60 |
As someone else pointed out, the rotor diameter on this machine is 3.2 meters, which is 10.58 feet.. This is one of the smallest turbines I've built in quite awhile. I selected that size because the output of the blades is matched well to the controller. And I just happened to have that set of blades in a box on the top shelf for the last two years. 
This is a photo of the rotor that's being used on the turbine, taken a couple years ago when I removed it from a different machine 
-- Chris off-grid in Northern Wisconsin, USA |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
I have been talking to some of the older gentlemen around here, looking for some info on the more oddball and rare wind generators for one of the members on the forum. A couple of brothers who installed house wiring after WW2 mentioned that a few farmhouses in windy exposed positions with 32 volt geared furling mills had a problem with, what they called "magnetic field saturation". They were saying the that at a certain rpm the magnets would lose their grip on the stator, perhaps due to magnetic interference from the coils and the turbine would over-speed. I assume your ferrite build at 1000 rpm is well short of that point and with magnets that size it would still exert a significant force anyway. I reckon with 24 volt batteries your classic and power limiting circuit are going to get a good workout. I will watch with interest, to see how the classic performs? good luck! yahoo I'm confused, no wait... maybe I'm not... |
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fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Hi Chris, I have been following your build on " Fieldlines", and it's good to see you taking the time to share it down under as well, within the fieldlines thread there has been a lot of good discussion on the technical side of building stators, flux, resistance which doesn't seem to make it to here anymore and it is worth having a read for people contemplating Axial Flux Alternators - HERE'S a quick link to the thread for anyone intrested . As for the gearing up work you have done with this build and taking the time to make a gear box and mount what I would think would be straight cut gears is well worth the effort for longivity and safety rather than taking the easier option of belt or chain , and hopfully all the engineering, planning and testing to match this gen with the classic 150 will become a reality soon . I have contemplated having a go at a ferrite, but have the luxury still having enough Neo's that I bought back before the price rise to build 2 more axials , but each time I get my teeth back into the AX400 , I seem to be jinxed to the fact that I have a more pressing project , hopfully in the comming year all of what I have pending will become a reality time permiting. I have read that Neo's raw materials are expected to drop in price , back to where who knows , but hopfully one day it will put Neo's back into the affordable range again, as they seem to be a perfect match to Ax Fx builds. PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| ChrisOlson Regular Member Joined: 19/01/2010 Location: United StatesPosts: 60 |
I believe those old 32 volt machines would've been either Jacobs Model 25's or Winchargers. Both of which used wound field DC generators with brushes and commutator. -- Chris off-grid in Northern Wisconsin, USA |
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| ChrisOlson Regular Member Joined: 19/01/2010 Location: United StatesPosts: 60 |
The geared drive in this one is oil bath roller chain. The oil bath roller chain drive has proven to be much quieter, and much more durable than gear to gear drives in my previous geared turbines. There's a reason that oil bath roller chain drives are used in severe duty applications like motor grader final drives, skid steer loader final drives, engine camshaft drives, 4 x 4 truck transfer cases, and so on. The roller chain drive is just about zero loss in transmission of power, with the only loss being the friction between the pins and side plates on the chain. I have a couple turbines that have over 12,000 hours on them with the oil bath chain drive and the chain and sprockets were still like new the last time I had the turbines down to service them. I'm using a 30 tooth drive and a 12 tooth driven in this machine, with the driven gear being a hardened chromemoly sprocket that I got from McMaster-Carr. The chain is a single row pre-stretched ANSI #40 with stainless pins and side plates, brass bushed rollers and the rollers are hardened 4140 chromemoly steel. I got the chain from McMaster-Carr too. Gear to gear drives create a lot of heat (and hence higher gearing losses). They are better suited to designs that require very close shaft spacings (such as in automotive transmissions). But you can't run gear to gear drives on shafts supported by ball bearings because the bearings develop a small amount of "play" after they break in, which will quickly destroy the gearset. With gear-to-gear drive I'd have to use tapered roller bearings running under preload to maintain the long-term backlash spec on the gearset. And then I'd be dealing with high losses in the gearset and high startup torque to turn the bearings. -- Chris off-grid in Northern Wisconsin, USA |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Hope you don't mind Chris. I found a photo of one of your previous boxes on my computer that shows spherical bearings with concentric collars and chain drive beautifully. 
There is a huge variety of flange cartridges, sprocket centres and bearings to chose from. this is "bread and butter" engineering for manufacturing in agriculture. Done correctly with quality parts, its very robust and easy to repair. yahoo I'm confused, no wait... maybe I'm not... |
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| ChrisOlson Regular Member Joined: 19/01/2010 Location: United StatesPosts: 60 |
Yes, I just uploaded a video to my YouTube account last night of the new machine - I will have it finished today and ready for the tower with just a few minor details like the generator cover to keep water and snow out of the gen, electrical junction box, etc: http://www.youtube.com/user/OlsonFarms#p/a/u/0/9hR_Kc-nJPI I used SKF (my wife is Swedish so I have to use those SKF bearings ) extended race angular contact ball bearings rated for both high axial and radial loading on the mainshaft. The PTO shaft has normal SKF ball bearings rated for high radial load, and 50% of the max radial load on axial loads.
The photo you showed was my prototype drive and I have made several changes to them since then. On the prototype I installed the pilot bearings inside the case. On the later ones I have gone to thru-shafts and align-bore the case bearing bores. This makes it easier to assemble and service the gearbox and provides better accuracy and alignment on the shaft centers. On some of the later gearcases I have built, I set the shaft centers slightly closer than nominal, allowing a little "slack" in the drive chain. Then used a snubber block, or idler, to adjust the chain backlash. On the last three four, including this one, I have gone away from that too because it's unnecessary. If the shaft centers are set properly, the roller chain will run for 20,000 hours between replacements with no adjustment required. It's very similar to the Detroit V-8 engine timing chain drives used for better than 50 years. -- Chris off-grid in Northern Wisconsin, USA |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
On that logic, I better start looking for a Norwegian bride  . If there is a bearing that is a pain to get at and I don't want to touch it for years, I will always install a fafnir bearing. Your ease with metric shows a bit of European influence there.
This is one product it pays to make sure it is genuine, there is a lot of substitution goes on(I mean bearings, not wives). Will be fascinating to see how those blades perform on the softer ferrite gen load. yahoo I'm confused, no wait... maybe I'm not... |
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| ChrisOlson Regular Member Joined: 19/01/2010 Location: United StatesPosts: 60 |
Indeed. Svenska Kullagerfabriken AB only builds balls bearings in Sweden and the roller bearings are made in USA. There are some pirated Chinese-built bearings with SKF markings and part numbers and I've run across them at NAPA and Carquest stores. If they are made in China, they are not genuine SKF even though they may say SKF and have SKF markings. Svenska Kullagerfabriken AB is the largest bearing manufacturer in the world and they build the bearings exclusively for GE, Rolls-Royce and Pratt & Whitney gas turbines, and for Vestas (Danish) wind turbines. What would really get me in the doghouse is putting German (FAG) bearings in my wind turbines 
-- Chris off-grid in Northern Wisconsin, USA |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
The mechanic that services my harvester has his own private joke. When he is asked for an inspection report, if he spots a FAG bearing or an obvious fake, he lists it under "sabotage". In the 90's I got offered FAG 205's for 24 cents each bulk price, no wonder resellers love em! profit and return business 
yahoo I'm confused, no wait... maybe I'm not... |
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