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My new toy


By electronbaby, Section Homebrewed Electricity
Posted on Tue Jul 1st, 2003 at 09:28:51 AM MST
New dual rotor I just finished.

This machine contains the stator I posted last week. I thought the coil height was too high. As it turns out, it works but it probably would be more efficient if I made the coils shorter after all.
Here is a pic of the tail pivot. This is an auto furling machine. Although it hasn't been tested yet, it will by the end of the week and I have to put the mast back on the truck to test it. Haven't got to it yet. :)
I used two types of mags on this one. It was just that I had the disc neos laying around and I just got enough rectangular blocks for the front. The disc neos on the bottom are 1 1/2" x 3/16" discs and the neos on the top rotor are 1" x 2" x 1/2" rectangular blocks. There are 12 mags on each rotor, and since this is a three phase machine, there are 9 coils. Three coils per 4 magnets.
Here you can see what Im talking about when I say the coils are too tall. This is the rear of the stator and since this rotor has disc mags, the mags pass somewhat through the center of the coil. But on the front rotor with the rectangular blocks, the mags pass over the lower 3/4 of the coil. Not the best way to do things, but it works for now.
I used brass screws to make 6 terminal posts around the rotor. The posts are at the beginning and end of each 3 coil series leg. This is so I can wire the stator in star or delta later on if I want without jeopardizing the strenth of the actual magnet wire in the coils (I glued it all down around the edge). I use jumpers to make up star.
This is a pic of the machine being spun by hand. Its putting out 24.39VAC. I would guess that it cut in occurs at around 110-120 RPM. This machine is wired in star now and if I put it in delta obviously it would take more speed to see the same voltage, but I would effectively raise my current. Since this is a 'low wind' machine I left it in star.      RoyR
My new toy | 9 comments (9 topical, 0 editorial)

Re: My new toy (none / 0) (#1)
by billf on Tue Jul 1st, 2003 at 01:52:27 PM MST
(User Info)

Looks good. A couple of points...insulate/seal the exposed connections on the stator. When the stator gets wet you will short out the coils. I've noticed a couple of the guys making connections this way...it will bite you eventually. Better to have longer leads and make connections in a 4x4 or larger box. Also consider a star/delta switch or have it furl early. While star is great for low winds, the coils will heat up and become inefficient probably above 12-15mph. With the sealed stator, cooling will become an issue. Just a couple of thoughts :) billf



Re: My new toy (none / 0) (#2)
by electronbaby (roy<at>windsine.org) on Tue Jul 1st, 2003 at 02:32:08 PM MST
(User Info) http://www.windsine.org

Thanks billf. The reason I did it this way, is because I cant count the number of machines I have lost a stator due to the wind and vibration actually breaking the wires inside the resin. This time I made sure I glued it all down and used terminals. I wasnt sure what my wiring scheme would be and the terminals helped tremendously. Its in star now but I think I will use relays to actually switch it to delta in higher winds. I will have to build some sort of RPM sensor or a second windspeed indicator to do this automatically, because I cannot rely on the voltage of the machine to tell me. I can however rely on the frequency but this gets tricky if you know what I mean. The voltage will always be fluctuating and the charge controllers pull it back down when its at a usable voltage. Its gonna be fun trying to accomplish this hehehe. Anyway, this machine isnt really tested yet and when I actually fly it I will paint over the terminals to seal them from the weather. Thanks for the advice Billf. I like the idea of a junction box. I could also make the switching circuitry fit in the box as well. Hmmmm...  Ill keep it in mind.  Thanks       RoyR
Have Fun!! RoyR KB2UHF
[ Parent ]


Re: My new toy (none / 0) (#3)
by billf on Tue Jul 1st, 2003 at 08:46:06 PM MST
(User Info)

It's a good time to build a machine as the summer winds aren't doing diddly squat. I think RonD had a solid state star/delta switcher designed that a lot of the guys liked. I can't remember his address (anyone jump in please). Anyway the best advice is "Keep It Simple". Less to fix when it breaks. billf

[ Parent ]


http://dsgnspec.com/ (none / 0) (#4)
by TomW on Tue Jul 1st, 2003 at 09:06:20 PM MST
(User Info)

I got one of RobD's tach juniors very nicely done unit:

http://dsgnspec.com/

is his website.

Cheers.

TomW

Light Travels Faster Than Sound, Which Is Why Some People Appear Bright Until You Hear Them Speak.


[ Parent ]



Re: http://dsgnspec.com/ (none / 0) (#9)
by windstuffnow (elenz(at)windstuffnow(dot)com) on Wed Jul 2nd, 2003 at 06:37:50 PM MST
(User Info) http://www.windstuffnow.com/main

   Robs star/delta switch works great!  Its going on 2 years now and it works flawlessly.  I did have to replace the relay I used once after a storm, clocking 650 watts through my 42 inch prop and the relay was only rated at 20 amps ( per pole) other than that its been a great mill.

   Nice job on your first mill!  I remember my first mill was pretty shabby, over alternated, under proped and basically a real dud!!  Had to learn somehow though

Have Fun
Ed

Have Fun! Windstuff Ed
[ Parent ]



Re: My new toy (none / 0) (#5)
by DanB (danb@*no spam*otherpower.com) on Wed Jul 2nd, 2003 at 08:25:01 AM MST
(User Info) http://www.otherpower.com/

I left mine open (unsealed like that) - and probably should've sealed them.  I guess my greatest concern is corrosion....

Although, considering the low voltage, and the fact that rain water is pretty much "distilled", it seems to me like shorting couldn't be problem as distilled water is actually an excellent insulator from my understanding.  But I'd agree, there is no harm in covering those up... but I don't expect shorting to be a problem when wet especially in a 12 volt machine.

[ Parent ]



Re: My new toy (none / 0) (#6)
by Mike on Wed Jul 2nd, 2003 at 09:51:17 AM MST
(User Info) http://www.bioelectrifier.com

Radio Shack has "Coax Seal," a gummy putty sold in rolls. It's perfect for any electrical connections exposed to the weather. I've used it to seal RF connectors on towers and after years of exposure the stuff is still soft and the insides are dry and shiny. You just tear off a piece, peel the paper backing off and mold it around the connection. The RS part number is 278-1645. - Mike http://www.bioelectrifier.com

[ Parent ]


Re: My new toy (none / 0) (#7)
by scoraigwind (magnet@scoraigwind.co.uk) on Wed Jul 2nd, 2003 at 03:51:38 PM MST
(User Info) http://www.scoraigwind.co.uk

Thanks for the nice pics, Roy

The alternator should work well but you do not say what size rotor blades or what tip speed ratio.

The tail hinge looks to have more back angle than side angle so it will furl early, but watch out when the wind gets stronger :-)

Why not solder long tails of multi-stranded wire onto the magnet wire so as to make connections elsewhere in shelter?  Embed the solder joins in the resin casting.

I found that a pilot coil in the stator gives good indication for rpm, and I connected it direct to a relay for star/delta switching.  But I never liked it so much in delta because it ran too fast.  And in star it was stalling.
Hugh Piggott http://www.scoraigwind.co.uk



Re: My new toy (none / 0) (#8)
by electronbaby (roy<at>windsine.org) on Wed Jul 2nd, 2003 at 05:40:49 PM MST
(User Info) http://www.windsine.org

Hugh, this is my first machine using the auto furling mechanism. I will get to testing it this weekend if all goes well. Your right about using the stranded wire to bring the connections inside a weather proof enclosure. I will probably try that on the next machine. I also had the same Idea of using an isolated coil to generate 12v at a much lower current. Just enough to power the relays to switch. I was thinking of mounting a couple small mags on the outside of one of the brake rotors, and using a small coil, maybe 200/250 turns of 22AWG wire to position in front of the mags. It will in essence be a secondary alternator strictly to power the relays to switch. The RPM at when it switched could be adjusted by moving the coil away from the magnets a certain small distance. I guess you could put them in the stator casting also but you would have to rely on some sort of variable resistance to change when it switched to delta. Possible some sort of potentiometer?? RoyR
Have Fun!! RoyR KB2UHF
[ Parent ]


My new toy | 9 comments (9 topical, 0 editorial)
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