Jensen Genny

[tajim]

I've been interested in windmills for quite sometime and have been reading this board off and on for the past couple years. After investigating some available units, I decided to take the plunge and put a windmill up from items I've purchased over the internet. I've never been satisfied with the performance of my windmill even though I live in a class 2 wind zone on the southeast US coast. I've seen days of 30 plus mph winds yet my windmill never had the expected output.

After reading a lot of posts on this board, I decided to build my own generator.

I'm putting this diary up to share my adventures with other windmill lovers.

I've done some preliminary design work over the past couple of months and have recently begun construction.

I decided on a 12 pole 18 coil design dual rotor with a cut in speed of 150 RPM due to the low wind class in my area.

Below is a picture of my initial design.

The stater design I have chosen is going to be a phenolic plate with dual coils with one on each side. I am going to try not to use resins in the design. I've included a picture of the phenolic plate which will have a bobbin style retainer to hold the coils in place. After assembly I plan to brush the coils with a coat of varnish to reduce the vibrations and magnetic forces within the coils.

The other images are from a template I used to develop the technique and of course it is made from phenolic not aluminum.

I'm currently machining the bearing housing, main shaft and support plates. I will post pictures of these and other items as they are made.

That's all for now.

[harrie]

I like it. Will the coils on each side of the stator,act as one and wired as one? Without resin, the cooling problem will be eliminated. also, the plastic washers should hold them to the stator very well. It will be great to see how this one comes out. Thanks for shareing.

Great Fun, Harrie

[dinges]

Looks nice.

Please resize your pictures though.

If you check out two of my posts, you'll notice that I've built my gennies a bit different from most people. One of the ideas behind it was that it would be easier to weatherproof the alternator that way. Still haven't made it weatherproof yet though.

http://www.fieldlines.com/story/2005/11/13/32021/791

http://www.fieldlines.com/story/2005/12/10/163646/91

Peter.

[DanB]

Looks like fun!  Your design seems very workable - there may be benifits to a solid phenolic stator like that - over resin - when it comes to strength.  But your hurting yourself by having that thick material between the coils - your airgap between the magnet rotors will be extreme.  When I build them and cast the coils in resin I find that even 1/8" more in the airgap can be a killer.  I expect youll need very large thick magnets to get the same power this way that you would otherwise get with smaller magnets and less of an airgap.  Just a thought!

[dinges]

I forgot to say, in my mini-genny I used epoxy-board, 1.59mm thick. The kind that's used in electronics.

[Flux]

Good luck

I am not as optimistic as the others.

Flux

[electrondady1]

 hello tajim
i'm just a novice builder, having built i think about five little genis , they all worked but fell short of my expectations so i dismantled and recycle the materials.(learning the hard way i guess) i have been studying this forum for about two years and i am begining to understand what is required to produce good power.
 your stator design is a novel approch . i had to look up the definition of phenolic. it would seem to be a good material to use.
when you have obtained the magnets and have assempled the mag rotors , you should be prepared to do a series of tests to obtain the optimal output. the whole point of a dual rotor design is to suspend the coils closely between  the two attracting magnetic fields. the closer the better.
 with the design you are proposing you would have the thickness of the phenolic stator plate, the thickness of two coils, 2 x the plastic bobbin thickness, 2 x  the retaining screw head, and then 2 x clearance to the rotors.
this would require you to sepperate the magnets a great deal. if you wish to avoid the use of a poured resin stator i suggest that you turn a coil in the conventional way and insert it into a precut whole in the phenolic stator.you will be able to run the mag rotors much closer together and thereby broduce a much stronger field of flux.

good luck, shawn

[kitno455]

i assume you will not be using the brass bolts to hold the coil spools right?

you have added quite a bit of material to the airgap this way...

allan

[reinoud]

Hi!,

i must say i like the design only wondered if it could be tweaked to use two nylon plates sandwiching a middle nylon plate. The outer nylon plates could be carved in so to let as much air in but still provide support for a thiner inside nylon plate. Would that give best of both worlds?

Reinoud

[tajim]

Tha brass nuts were just for the template. It's hard to see in the pictures, but I have a average gap between the rotor plates of less than a inch. I am using 1x1.5x.5 n 40 neos on the mags. I found a formula for the calculation of the number of turns on this site. I ended up with 414 turns per phase.

N = voltage / (A x R x B x P x 2)

A= Area of magnets (.0009675) sq. meters

R= Revolutions per second (2.5)   150 rpm. I picked this due to low wind in my area.

B= magnetic flux in tesla (0.5) not sure, only a guess

P= number of poles

N= 12volts / (.0009675 x 2.5 x .5 x 12 x 2)

N= 414 turns per phase                        

Thanks Windstuff Ed!

414/6 = 69 turns per coil (six coils per phase)

now since I have 2 coils per given area, one on each side, I will divide this by 2. this gives me 35 turns per coil per side. This should fit nicely on the stator plate. The issue of course is thickness. The 35 turns per side at 18 ga. wire seems to be just about all I can fit on the bobbins and still remain less than an inch on the rotors.

The big question is star or delta?

According to the formulas, if I go with star, then I can divide by 1.732 which equals 40 turns per coil. Which in turn means that I can have 20 turns per side and maybe use a bigger wire?

Not sure which way to go yet.