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How to dertermine rating
By mettleramiel, Section Newbies Posted on Sat Mar 17th, 2007 at 09:25:41 PM MST
Rating my windmill

I am near the final stages of building my windmill, but before I put her up, I did come up with a question. Turning it by hand, I reach cut-in at about 160 rpm and I get between 0.8 to 1.0 amps into my batteries. Now I have to ask, how do I rate the wattage of my windmill? I know that watts = volts x amps and that I will get more amps than that as the rpms pick up, but what I am asking is when I see a windmill that is stated as being a 100 watt model, at what rpm or windspeed are they getting 100 watts? Everytime I tell someone that I am building a wind turbine, they always ask how many watts I will get out of it and I would like to give them an answer other than "I know that it is at least 12." Thanks for the help.

How to dertermine rating | 4 comments (4 topical, 0 editorial)

Re: How to dertermine rating (3.00 / 0) (#1)
by CmeBREW (smke833f@hotmail.com) on Sat Mar 17th, 2007 at 03:48:48 PM MST
(User Info)

I think you should give alittle more Info. about your Generator and rotor size before someone can give a rough estimate. Is it a Ametek, a motor conversion, treadmill motor, dc motor, a dual rotor alternator? How big are the magnets--how many mags--coils, etc,etc? Are your batteries 12v or 24v? From the sound of it, it should do more than 100watts. Any pictures?

Re: How to dertermine rating (3.00 / 0) (#2)
by mettleramiel on Sat Mar 17th, 2007 at 06:51:50 PM MST
(User Info)

Sorry, I thought that giving my current output was enough. It is a single rotor 3 phase, 9 coils 60 turns of AWG 14, 12 1"x2"x1/2" magnets. No pictures up yet, not until I am done, which will be very soon (paint drying on enerything right now) hopeing to be done for tommorrow, my birthday!

[ Parent ]

Re: How to dertermine rating (3.00 / 0) (#3)
by DanB (danb@*no spam*otherpower.com) on Sun Mar 18th, 2007 at 12:16:01 AM MST
(User Info) http://www.otherpower.com/

'Watt' ratings are nice for marketing but don't really mean much on a wind turbine. I guess most folks would 'rate' the machine at the maximum wattage it can produce sustained without burning out. Yours can probably stand up to 600 or 700 watts sustained output I expect.

The most important 'rating' for a wind turbine is the blade diameter or the swept area.

[ Parent ]

Re: How to dertermine rating (3.00 / 0) (#4)
by Flux on Sun Mar 18th, 2007 at 01:03:42 AM MST
(User Info)

Dan has covered the question as you asked it and there is no consistent rating for the commercial machines.

What your question probably meant was how much can you expect to get out of it.

Again it depends on the blades and that is the thing that you don't even mention.

Assuming you are planning to use wooden blades similar to Dan's your cut in would suit an 8ft prop.It should match fairly well but with just a single rotor it will run a bit fast and you will not stall. As a dual rotor it would have been a 24v winding so you can only let it produce the same amps as a normal 24v stator. I would think you were pushing it to let it run beyond 500W for significant periods and perhaps calling it 400W would be safer at 12v. Make sure your furling can hold it down to this sort of power level.

If you are using smaller blades then it will probably stall and you may have less to worry about regarding burn out, but unless you use a lower tsr prop it will need the gap between rotor and stator increasing for a decent match.

Without prop details that is all I can offer.

Flux

[ Parent ]

How to dertermine rating | 4 comments (4 topical, 0 editorial)

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