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Forum Index : Windmills : VAWT, 9 coil 12 pole N42 need help
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| megantara Newbie  Joined: 25/09/2014 Location: IndonesiaPosts: 7 |
I've built a lenz2 type turbine (1m height, 0.9m diameter), with 9 coils (170 turns, 1mm wire diameter each), and 1" x 2" x 0.5" N42 magnets. Average wind speed for a week is around 3-6m/s with 10-12m/s gusts resistance per phase (3 coils in series) is 3.4-3.6 ohms Questions: 1. with wind speed around 3m/s, each phase produces around 0.9-1.2v (roughly 40-50rpm) 2. will fiberglass resin (clear, with polyurethane-like catalyst smell) generate enough heat during curing to make coils insulates get damaged, other than using talk (CaCO3) is there any other requirement to make good stator cast? 3. i stupidly stuck my magnet to baking pan (not smart, didn't finish reading materials), then stuck the pan with magnets to round iron plate (3mm thick). Is there a good way to remove the magnets without damaging it. Note: can't turn/pull the pan from iron plate 4. is 3.4-3.6 ohms/phase a good number? what resistance should i look if i decide to make new stator? (i want my system to work @ average 4-6 m/s wind => 50-80rpm) 5. is my stator coil damaged as it only produce 3-5 volts open circuit @ 40-60rpm 6. is it normal if the output seems to depend on the load? e.g: - with 12v led series, circuit voltage seems capped @ 10volts, and wont rise more - with 4v flashlight battery, voltage wont rise above 4.2v thank you for any inputs Edit: How many amps can i expect from using 1mm magnet wire? I'm setting up 12v system. |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Too many questions in one post. Your better off spreading them out a bit over several days to get a response. Some answers 1. Low RPM, dont expect much out of the alternator. 2. Nah, the copper enamel insulation is designed to handle a fair bit of heat. 3. Wood block, push/tap magnet from side. 4. duno 5. duno. Seams a bit low for 170 turns. 6. Yes, thats normal. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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Tinker Guru  Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Hi, You did not mention how many magnets you are using, I assume you are aware there are optimal magnet/ coil ratios. For 9 coils that would be 12 magnets. The coils are then connected: ABCABCABC. You might want to lower your expectations for the Lenz 2 output. I have been playing with several versions (present one has 5 blades @ 2m diameter) and they all have been disappointing. Never saw more than 1A charging output and that was in a howling gale and using a voltage booster to raise the output high enough to charge my 24V battery bank. I should mention I have a 1:6 planetary gearbox between the Lenz 2 and alternator (washing machine type). My Lenz 2 simply does not spin fast enough to reach cutin voltage and there is no power at low RPM. Its a popular design for beginners but I doubt there are any that generate useful power. Klaus |
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| megantara Newbie Joined: 25/09/2014 Location: IndonesiaPosts: 7 |
Klaus: Yes, i'm using 9 coil 12 pole configuration with all wire coming out from stator. Glenn: I'm planning to build a new set of stator-rotor, and make new thread for report and question/discussion. Hopefully it will help others who want to build wind turbine and don't know where to start. (took me 4 months for me to finish this one, lol) At least i've learnt a lot from building this one. I hope with many mentor from this forum i can make better design. Consider this thread closed. Thanks for response. |
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| electrondady1 Senior Member  Joined: 12/02/2009 Location: CanadaPosts: 208 |
did you follow ed's instructions at all or just wing it Indonesian style? the proportions don't sound right at all. 1m x.9m ? can't remember ed using pie plates or cake pans. maybe you could contact windstuffnow and get it straight |
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| megantara Newbie Joined: 25/09/2014 Location: IndonesiaPosts: 7 |
The proportion is not straight, should be 1.2m x .9m (4 ft x 3ft), 1x1 aluminum sheet is the largest i can get, thus came that 1x.9 the ribs are to ed's design... only the height is modified. For my defense, i didn't have any clue that steel thickness will affect magnet strength... now after the pan stuck to 3mm iron plate, the magnetic force is too strong that i can't remove or slide. Gonna try wood trick next weekend. I think i did my alternator good enough (should be better without the pan). I draw circle, then put my coils in 40 degrees angle, and the magnet is 30 degrees. Update: Today after work, i try putting another pan under the stator, and the output rose by 2v. Apparently the flux better with pan under stator. I'm gonna get another iron disc before going to work tomorrow to see if it will work better, then go for dual rotor. Note: Its my first build, and i'm quite proud/happy just seeing that it didn't fail. It was intended to learn the basics. i believe no knowledge can be gained without making mistakes, mistake is the best teacher IMO. |
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| Jarbar Senior Member Joined: 03/02/2008 Location: AustraliaPosts: 224 |
Megantra, I am enjoying your honesty and willingness to present your developments here. Perseverance will indeed be rewarded,just take the learning's, accept positive criticisms and keep going. 
Anthony "Creativity is detirmined by the way you hold your tounge".My Father "Your generation will have to correct the problems made by mine".My Grandfather. |
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fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Megantantra, I will give you my experience of building Axial Flux type alts, but I would strongly advise to leave the VAWTs alone and build a Axial Flux wind turbine HAWT and then you might have some usable power . Your 50mm x 25mm x 12mm N38 Neo Magnets need to be mounted on a 8 ~ 10mm steel plate(dont know what a pan is). If a pin sticks to the plate behind the magnet you are loosing Flux concentration & Density. Mount the plates on there bearing with the magnet faces 15 ~ 18mm apart and make a test coil , only 10 or 15 turns out of any size copper wire . Attach the 2 outputs of the Test coil to a Bridge Rec and put a good size DC capacitor across the + & - of the rec and then attach your MM leads. Spin the dual rotor at you desired RPM and take the DC reading of the MM , then the next is only an example . Say your test coil is 10 turns and the DC volts on the MM read 2vdc @ 50rpm . Then - 2 / 10 = .2 ....then allow star connection and 3 coils in series - .2 x 1.75 x 3 = .35 x 3 = 1.05Vdc per turn @50rpm . Charge for a 12v system = 15v + 1.3V Bridge Rectifier loss + .7 v wiring Loss = 17vdc the alt need to be at for the desired RPM ... 50 17vdc / 1.05vdc = 16.19 turns per coil or go (17)... so I would use the biggest copper wire possible and always room limits this or you can use 2 or 3 smaller wires in hand to get the wire DIA up for max current with no heat .. WARNING HEAT KILLS THESE ALTS VERY QUICKLY . but if you continue to build the VAWT you will not have to worry about heat. Use Epoxy Resin not regular Polyester Resin to make your stator as it shrinks and warps to easily and have fun learning .. Post some pics PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| electrondady1 Senior Member Joined: 12/02/2009 Location: CanadaPosts: 208 |
ed got a winner with his lenz2 design , to the point that at least 1/2 dozen people started building them in kit form and tried to pass them off as there own design. he backed a vertical forum for a few year and that's where i found him to be very friendly and helpful. it was your 170 turn coils that got me thinking something wasn't right with your machine . once you get that second rotor in place you will find you have more than enough turns. good luck. |
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| megantara Newbie Joined: 25/09/2014 Location: IndonesiaPosts: 7 |
I used fiberglass resin for stator, and the result indeed not good, got some crack when its done. It costs around US$ 2 a liter, compared to $25 epoxy resin (resin+hardener). But i'm thinking to use epoxy once i get the best configuration for my need. took some vids afternoon charging 4v flashlight battery http://youtu.be/RXaU_EWZJ6E with anemometer, 1-3m/s wind http://youtu.be/AzQVzKvRLBQ stator, rotor, and pan http://youtu.be/9uMcHMrPvOY took just now http://youtu.be/AMfbBhyE4eA 
sorry... was using phone camera to take the those Edit: The frame was shaking quite awful in 4+ m/s wind, and the orange thingy hanging on the frame is anemometer tied to a string with tails behind. Crude, but that's the only thing i have lying around before taking pic/vid. thank you for your feedbacks, i'm gonna see what can be done with this while saving to buy new set of magnet. Hopefully i can get them by next month. For now i'll research more, and review the things i did wrong in my 1st attempt. This project was money well spent... much better than spending it on bar or gadgets i wont use fully (like iphone or ipad, lol). |
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| electrondady1 Senior Member Joined: 12/02/2009 Location: CanadaPosts: 208 |
i 've built close to a dozen alternators and never had a problem with polyester resin as long as you let it cure slowly . it's not suitable for bedding mag rotors 'cause it shrinks . your mill looks good . is it balanced? as in, turn it side ways and see if it favors one wing over another. |
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| megantara Newbie Joined: 25/09/2014 Location: IndonesiaPosts: 7 |
Don't see if it favors any wings yet, but i'll check it next sunday. I think i can check it if it's laid down horizontally while replacing the pan with another iron disc. For now i don't think there's anything to report. By the way, if i make test coil like Phill said, is there any difference with coil inner area? Currently this stator has 1" x 2" hole (can fit a magnet tightly), but gonna try with slightly trapezoidal shape (like 1" top width, 1/2" bottom width, height 2"). Still trying to summarize a thread in fieldline about coil shape, something concerning half magnet thick, 2/3 magnet width, airgap, etc... There are so many things to learn, for unknown reason i have hard time understanding terms and theories, maybe skull got too thick and brain squeezed in. |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
There is lots of info on the net about what you asked but it takes a little to sort out. I had a look and found this:coil size Read the first bit what happens if your magnet is too big (in area) for the coil. Ideally, the inside of the coil is shaped like the magnet. If you make the coil inside smaller then not all of the turns produce power. If you make it bigger then you require more wire for a given No. of turns and that means extra resistance. Klaus |
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| megantara Newbie Joined: 25/09/2014 Location: IndonesiaPosts: 7 |
Yeah, i've read 6pie... its one of the first pages i read, but i can't absorb much info from it. Now i'm trying to understand what people discussing here: Coil shape for axial flux generator I'm a "seeing is believing kind of guy", its hard to understand theories without duplicating and see what it does. i'm also strugling with ed windstufnow's formula about I believe this is one formula i need to follow for my next design. Edit: 1 question: if P=V*I, I=V*R (P=V*V/R) is it correct if i assume current is actually omitted (unknown variable factor) and the key factor to generator is V and R, and alternator watt rating depends on open voltage squared * coil resistance? (because voltage is the output from alternator rpm, and phase resistance is constant) |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
if you are looking at this page http://www.windstuffnow.com/main/generator.htm then you need to look at it in two separate sections to make sense in your brain. The first section is about calculating volts per revolution or revolutions per volt. open voltage is the generator spinning with no load or battery connected (amps). so as the turbine spins faster the voltage increases at a constant rate. The next part is about using this information to calculate the power generated when the turbine is connected to a battery. The turbine will spin easily until the volts per revolution are equal to the batteries resting voltage. As the turbine spins faster the batteries voltage starts to rise and the resistance of the battery bank gets higher and puts an increasing load on the turbine as it spins faster. What he is saying in the example is that a 12 volt battery bank will be at its highest practical load at 14.6 volts, as the battery voltage rises above this point the battery will be getting close to fully charged or starting to turn the water in the battery cells to gases instead of loading the turbine. what gets turned into amps is everything between the battery voltage (14.6) and what the open voltage would have been with no load at that turbine RPM. So in the example at 885 RPM 20.6 (open) volts minus 14.6 (battery) volts equals 6 volts of potential power. 6 volts divided by the stator ohms 6/0.6 = 10 Amps produced 10 amps * 14.6 volts = 146 watts from this you can play with the numbers. what if I used a 48 volt battery (58.4 volts) what would be the rpm at 10 amps produced? or changed my stator wire resistance? once you can understand this basic concept everything else is just small added steps to make your calculations more accurate. I'm confused, no wait... maybe I'm not... |
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