DIY windmill, need help with generator/motor among other things

[Eric Sharet]

Alright, well i've been thinking of building a windmill to power a friends cottage. i want to do this at minimal cost, recycling anything i can. I've been spending alot of time reading up and think i understand most things. Now from what i've read many people are building there own generator them self's, i'd rather not do this due to reliability issues and maybe having to re-do it a few time to get it right, not to mention the cost for supply's. I've decided to use a variable speed DC blower motor from a high efficiency furnace. i want to use this motor cause it cost me nothing and since i work in the heating and cooling industry i have access to many used motor from old furnaces and such for free. i'm unsure if this motor will be suited for the job. i'm not sure of the best way to test it, anyone have any idea's?

Here's is what i know about the motor so far. i will copy what it has on the rating plate.

GE Motors
ECM programmable motor
GE modle no: 5SME39HL0003
Serial no:0009S6
Date code:19SHX
HP: 1/2 RPM: 0-1300 Volts: 120/240 Amps: 6.40/4.30
Cust Modle no:HD44AE116
Rot: CCW

Now what i've done is i've removed the back housing and have removed all the ECM electronics, what i'm left with is a small 3 phase AC generator. i've hooked up my digital multimeter (Sperry DM-350)to 2 of the 3 leads, set it to 600VAC, spinning the shaft by hand i can get 15V easy. i hooked up a power drill to the shaft and at full speed i has able to get a bit over 270V. not sure if you need to know the specs of the drill but here they are, it's a 120V 4.5A variable speed drill, RPM: 0-2700.

now i'm thinking this motor will work find but i haven't been able to figure out how much Watt's i can get out of it so i can size a rectifier. my multimeter has a setting for Amp's but i haven't been able to get a reading off it. i though maybe it was due to the fact that there was no load on the generator so i hooked it up to a 120V, 150W coffee grinder and spun the generator with the drill, the grinder worked, i ran over 250V, 2 phase to it and it's didn't burn out but i still wasn't able to get a amp's reading, maybe i'm not using it right, i don't know.

So does anyone have any suggestions? any ideas on how i could improve the performance of this generator/motor? also if it will not provide enough power, could i ad a second one and have them both charging the same battery banks?

I'm not 100% clear on what advantages i would have running a higher volt system, say 48V rather then 12V. Could someone possibly provide some clarification? Also i think i may want to got with a VAWT, it looks to be easier to build and set up, also it would not use as much space and i think it would be easier to attach 2 generators to it if needed. what are your opinions on this?

[Stewart Corman]

Eric,
you are starting with several unfounded perspectives

a small 3 phase AC generatornot DC as you first stated!

here you have said it all .. a 1/2 hp motor can deliver about 350watts
hardly enough to power a few light bulbs ...especially if you use a battery bank which loses 50% of the power stored

Also i think i may want to got with a VAWT, it looks to be easier to build and set up,

now that's a can of worms!
there is a very obvious reason that there are currently no major manufacturers
of VAWTs ...duh, they don't work!

there are many threads on this subject of matching a generator to a turbine rotor, and Mark and I practically beat this to death
I agree that you don't want to start creating your own generator ..
they are NOT cheap if you have to buy magnets and wire and epoxy, etc and pay for machining

All major manufacturers are going to high voltage systems, not 12v or even 48v.
Simple math for transmission losses will dictate the above.

All that said, if you do a search on my posts, you'll see that a 3 phase 440v servo motor is a very viable option and they come cheap on eBay

check out this dealer who posts new items daily:
http://stores.ebay.com/hgrauctions

example:
ALLEN-BRADLEY 1326AB-B410G AC SERVO MOTOR, NEW $109.38 on Mar24th
not bad for a $2200 PM servo motor

get one with as low an rpm rating as possible ..mine is 3000rpm and can handle 2KW
the key number which you DIDN'T measure is the internal resistance of the coils
hint: smaller is better

Do some homework and we can discuss further

Stew Corman from sunny Endicott

[Eric Sharet]

Well it would seem your right, i think will have to do some more reading. Just to clerify, the motor i am using is a DC EMC motor thats was used in Carrier furnaces, yet once i removed the electronics from it i was left me with a 3 phase AC generator. it's to bad a VAWT will not suit my needs, yet i guess it really isn't that much trouble to build a HAWT.

Could i use say 2 or 3 of these motors to get the power i require? cause i can get over 200 volts out of one. i would just be nice to be able to do something with them since there free to me and what really matters is that they would be recycled. i think the internal resistance of the coils is 0.010 if i've done it right. there way i'll keep my eyes open for something better, of the top of your head, do you know any machinery or appliances that may have a better suited motor?

[Rob Beckers]

Hi Eric,

Admittedly I do not know the newer DC fan motors for HVAC too well. What I've heard is that they do have permanent magnets, and 3-phase wiring, just like any permanent magnet alternator. They are then driven by grid AC that's rectified to DC, which is pulled through an inverter that turns it into 3-phase AC with just the right phasing to turn the motor at a specific RPM. Change the frequency and the RPM changes. Seems this makes much more efficient motors than the regular AC induction types. If that is what you have, it should make a nice PM alternator for a small wind turbine.

As Stew mentioned, 1/2 horsepower is around 350 Watt, and that would be at a whopping 1300 RPM, so don't expect too much from this. This is not going to power a cottage, unless you limit yourself to a few CFL bulbs, and even that won't be easy.

Now, if you want to use it for some cheap experimenting that's another story. I bet you can make a nice little VAWT or HAWT with it. You'd need to get the RPM up though, to get any power out of this alternator, so that is either a gearbox or belt drive, or blades running at high tip-speed-ratio (TSR). The latter would rule out Savonius type VAWTs, they run at a TSR of about 0.8 at best (a HAWT would typically do 7 - 9, meaning the blade tips are moving at 7x to 9x the speed of the wind). Making a little two bladed regular HAWT, using wooden blades that you can shape with hand tools, would be pretty easy. A blade diameter (tip-to-tip) of around 1.2 meters will get you about 350 Watt at 11 m/s windspeed, at about 1200 RPM, and a TSR of 7.

The voltage coming out is much too high to hook up directly to batteries. You would need something like a transformer to move it down to battery voltage (though that comes with its own list of problems). If it reaches battery voltage at around 500 - 600 RPM you would be loading up the turbine pretty well for the mid-strength winds.

Take a look at Hugh Piggott's design notes (http://users.aber.ac.uk/iri/WIND/TECH/WPcourse/index.html). It's a very good, and understandable, introduction to wind turbines, blades, TSR etc.

As I said, don't expect too much from this. If you build it, it probably won't survive for too long in the wind. It will be a great learning tool though.

-RoB-

P.S. If you are going to build something please post back here (with pictures)! We want to hear about it! :cool:

[Jonathan Kraidin]

You can read my web tutorial and see if this helps. It covers the F&P motor and axial flux design. It covers everything from the anchors on up.

Read it here (http://www.mindchallenger.com/wind)