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Forum Index : Windmills : micro wind turbin
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| raawind Newbie  Joined: 22/02/2012 Location: United StatesPosts: 5 |
Hello every one this is very first forum and i'm very excited. i have been playing around with wind solar for a few years now and i'm hooked. My question is whats your thoughts on micro wind turbins.? I live on the skirts of a good size city million and a half people my mast is about 30' in the air and winds a low especial in the summer. I built one last yr a 12 volt set up for the ground up. and this yr i'm working on a new set up a 24 volt 135 watt turbine it very small and light. the one that been used right now works ok it's a 36 volt pma in high winds it puts out about 18 volts 1.5 to 2 amps the blades are 28" 3 of them, i'm in the proces swapping out the baldes with 11 blade 60" set up which should get me some more speed and amps. |
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yahoo2 Guru  Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
welcome to the forum raawind, thoughts about micro wind turbines Hmmmm they are a lot of fun look very cool you will learn a lot flying a set of blades that are noisy will result in a friendly neighborhood lynching. I have found the best way to get one to produce a lot of power is to secretly wire a solar panel in and forget to mention it to visitors. 
It will be interesting to see how you get on with the 60 inch blades, my gut instinct says they will not spin very fast, but I have never seen a set flying. What do you think was limiting the 28" set. generator load, turbulence? I'm confused, no wait... maybe I'm not... |
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| raawind Newbie Joined: 22/02/2012 Location: United StatesPosts: 5 |
It seem to me yahoo2 and by the thanks for the warm welcome. Here whats i thing is limting the 28' {1}they need a good wind to get them started under a load at least 7 to 10 mph [2]. It takes a lot of wind to get it up to to peak voltage It's a 35? volt pma and i have never seen more than 18 or so volts, it's proble has hit higher but not when i'm a round. We get some nasty wind storm up here in the no. eastern usa in the winter time, there been nights i though that the wind was gonna rip it off the mast. i'm not sure how much my load has to do with it, i'm running a blocking diode, my battery bank is a good size 8 125 amp hr agm battries, it could be turblence but i dont think so cause when the wind wiping that thing is screeming. So i gather form your comment yahoo2 that the 11 sword like 60" baldes i'm looking at are not the answere. 
Remenber i live in the city? and i realy dont want to drive the neighbors crazy and dont want to scary them to death with 8ft blades wipping at 400 rpm'sin my back yard. they already think i'm a litle off center.  with my solar evacuate hot water system on my roof..  Are those bigger blades ive seen on the the back shed quite?.
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
thanks for the info raawind, generally the more blades and the larger the rotor diameter the slower a turbine will spin. Have a read of this basic explanation of Tip Speed Ratio It will give you an indication of what to expect. I would like to know how you measure the voltage. If you are charging 12 volt agm batteries and measuring the battery voltage then they are fully charged at 14.2 -14.4 volts, 18 volts DC will cause battery damage. If they are a 24 volt bank and you are measuring 18 volts on the turbine side of the diode then you are not reaching the battery voltage that means no charging is happening. I am suspicious that something is not quite right with your turbine, I would expect a 3 blade 28 inch blade (60 inch diameter swept area rotor) to be spinning well at 7 mph and generating good power at 10 mph. I have just done some work on two turbines with 28 inch blades, at 10 mph the 200 watter puts out 45 watts and the 300 watt machine produces 80 - 90 watts. I think the 200 watt turbine would run faster and produce more power with 24 inch blades. yahoo I'm confused, no wait... maybe I'm not... |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
The blades in this photo are some of the best I have seen on a micro turbine. This is a SWEA but the chinese knockoff is almost as good. Somehow the rotor self limits its rpm's in strong winds without making much noise at all. As you can see from the power curve although it is rated at 300 watts in clean flowing air it can produce a lot more given the right conditions. The one I work on is in a particularly windy spot and regularly hits the 40 amp limit on the controller in cool weather, that is 500+ watts. From my experience the graph is a bit optimistic at lower wind speeds and conservative at the upper end, I have not seen that dip in power at 10 m/s it flattens out but keeps climbing. 
I'm confused, no wait... maybe I'm not... |
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| raawind Newbie Joined: 22/02/2012 Location: United StatesPosts: 5 |
Yahoo2, Some times when the wind blowing it just cant seem to catch the wind and hold it's course. and other times it hooks up and screens. Your right at 18 volts my battries arn't chargeing cause i'm running a 24 volt set up it was 12. I'm checking out put voltage right at turbin input before diode and battries with a volt meter, battery volts are around 24 volts right now i charged them up. I'm not getting even close to the #'s your getting. I don't have a wind meter i get my #'s from the local weather station so my #'s are proble off on wind speed but my out put#'s are good. - my blades are nothing like those only blades i see are just the every day ebay ones. I backed out of that 11 blade sale but now i'm at a lost. Thanks for the tsr link very help full. It seems like thats whats happen it gets up to speed then falls on it's face. 
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| raawind Newbie Joined: 22/02/2012 Location: United StatesPosts: 5 |
where can i find blades like those and will they fit a 5/8's shaft. there so many on ebay and every one has a sale pitch how theres are better and why- i swear thy all use the same video's The 24" blades mention is that with hub or just blades. |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
The blades in the photo are available as spare parts but are not cheap and the hub supplied fits a tapered shaft, needs a lot of work to adapt it. If you are looking for blades for the new turbine that are cheap, quiet and reasonably robust, these may be OK windy nation 24 inch turbo torque carefully drill the 1/2 inch hub out to 5/8. The trick here is finding or making something the right shape that will support the hub from the back. edit I see they make a 5/8 stainless steel arbour that might be an option I would not be fitting new blades to your existing turbine until you have worked out why it is not getting up to 26 volts. If it is designed as a 12 volt turbine it may not be capable of reaching the higher voltage needed to charge a 24 volt system no matter how fast you spin it, this is something you may need to bench test. Most turbines I work on manage to hit charging voltage in a reasonably light wind. The problems I find the most are poor electrical connections and/or incorrect wiring, it pays to closely look at everything. The standard turbine has 3 wires and 3 diodes configured as a bridge rectifier to convert the AC to DC, if yours is not like this, then I cant offer any advice without some info about how the thing is wired. yahoo I'm confused, no wait... maybe I'm not... |
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| raawind Newbie Joined: 22/02/2012 Location: United StatesPosts: 5 |
yahoo2 my pma is a tri volt 12-24-36 so unless i was ripped off theres some wrong. we had a great 3 days of wind up her this weeken sat been the best 25 t0 40 mph winds you would think i would get some good #'s but no nothing over 20 volts, my batts should be fully charged but there not!  . I thing your right i need to do some testing- check wiring, etc. i've included a pic of my old and new bird - old bird is in air Thanks raawind.
Also i'm kicking around the idea of of picking up a 2 blade hub after a post i read on fluring?? 
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