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Old Jan 19, 2004, 12:36 AM
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Ohio, USA
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Glenn-

My admittedly rudimentary understanding is that a Star winding is more suited to direct drive, while a Delta winding is more suited to a geared drive.

To generalize, all else being equal, the Star winding provides lower RPM but more torque, which helps in turning a prop without a gearbox. The Delta winding produces higher RPM but less torque, so a gearbox may be necessary to use the same prop.

Perhaps one of the more knowledgeable posters will confirm this.

Your description of how to test the windings sounds just right. That's how I did it.

- Jeff
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Old Jan 19, 2004, 12:51 AM
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I don't consider myself more "knowledgeable" but you are correct jeff.
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Old Jan 19, 2004, 01:14 AM
Why not Delta?
rysium's Avatar
Sacramento, CA
Joined Jun 2003
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Quote:
Originally posted by galloping gimp
My admittedly rudimentary understanding is that a Star winding is more suited to direct drive, while a Delta winding is more suited to a geared drive.
Someone posted here, that star is more dificult to work for ESC. What is the story with that?

I need to wind a small 19g direct drive motor for my mini (micro) Ultimate Biplane (16 in wingspan, aiming at about 4-5 oz RTF weight). Because I don't want any gearbox therefore I will need every bit of torque I can get, so help me out with it, please.

I need the motor to be able to turn the biggest prop that is possible (Max static thrust) using no more than 5A from 2s 350 LiPo.

RysiuM
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Old Jan 19, 2004, 01:45 AM
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RysiuM-

I, too, have read that the Star winding is more difficult for the controller to handle. I've also read that the problem is less likely to occur if you replace the ring magnet with stronger magnets, as so many of us have done.

ESCs with adjustable timing can help, too.

That said, my CD-ROM brushless with Star winding worked fine with my (non-adjustable) Jeti 08-3P controller, even with the stock ring magnet. It worked better (less current, cooler operation) when I replaced the ring magnet with 12 N45 magnets.

I think you can only experiment and see what happens.

- Jeff
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Old Jan 19, 2004, 01:56 AM
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I had trouble with a low wind hot motor that I put N45s in and going from medium speed start up to slow start solved the problem.It would just jitter if I quickly went from no throttle to full.I could get it to start but only if I wiggled the throttle at start up then once it started it would run fine but would suck on a plane.Matt
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Old Jan 19, 2004, 02:04 AM
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ssatoru's Avatar
Chiba, Japan
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double wire

Quote:
Originally posted by soundman
Some people have been double winding.....what effect does double (or more) winding have, examples:

a 30 turn single wind motor vs a 30 turn double wind motor.

a 30 turn single wind motor vs a 15 turn double wind motor.

soundman
Let me try to explain. I am not 100% sure about it. Please anyone give correction. Actually I use double turn mostly to have more variety from less variant of wire.

0.3 mm dia wire double is about the same as 0.4 mm wire. i.e. Cross section area is about the same.
((0.3mm / 2) ^2 * pi * 2 = 0.141 mm2, (0.4mm / 2) ^2 * pi = 0.126 mm2).

If the area section of copper is the same (for example filled fully), 30 turn double will be the same as 30 turn single.

Some say you can wind smaller wire more than thicker wire but it is not true. (There is a chance you can fill the gap of edge near the winding area with smaller wire though.)

Some say it is better to have more surface area and double wire does have more surface area. I am not sure of this effect.

Satoru
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Old Jan 19, 2004, 06:40 AM
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QUOTE:
Some say it is better to have more surface area and double wire does have more surface area. I am not sure of this effect.

Satoru


TRUE.
and this is because electrons are lazy seeking the path of least resistance so that they avoid flowing through the center of the wire and prefer to flow near the outer surface----therefore a double wind increases the surface area about 33 % vs. / single wind.

Roger aka GIFLYRC
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Old Jan 19, 2004, 06:51 AM
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Depdog

You are correct about checking continuity--

check the wires and between wires using R x 1

check the wires to the stator using R x ( the highest setting on your meter) looking for high resistance shorts that break down under power

Keep in mind that you can read continuity through your body at this high setting so avoid contact with the meter probes

Roger aka GIFLYRC
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Old Jan 19, 2004, 06:59 AM
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So would I be right in saying that if you compare a 30 turn single wind with a 30 turn double wind - they would both have the same rpm & power characteristics, but the double wind would be more efficient?
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Old Jan 19, 2004, 09:05 AM
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Quote
soundman
So would I be right in saying that if you compare a 30 turn single wind with a 30 turn double wind - they would both have the same rpm & power characteristics, but the double wind would be more efficient

I don't know the answer to that one and perhaps the only way to find out would be to wind two identical stators one with a single wire and the other with a double wind and then compare results

Roger aka GIFLYRC
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Old Jan 19, 2004, 09:36 AM
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From my days racing electric cars, a double wind would have more torque vs the single wind, but the single will have slightly more RPM's.

I have a problem which I believe is in my quantity of magnets. I have the large stator Toshiba drive with bearings that I rewound to 27 turn single with #26 wire (green Radio shack) "Star" config. and put 8 n45 magnets in the bell N-S-N-S-N-S-N-S at 45 degree increments. The motor stutters at start then will only go to 1/3 throttle and the esc shuts down. Amp readings are no more than .6 amps. Should the number of magnets be greater than stator poles, ie.: 12 magnets to 9 poles ? My friend and I have the exact same problem and have gone to 4 magnets and it does the same. HELP!

Rick
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Old Jan 19, 2004, 11:34 AM
Hi Wattage Electrics - Cool
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Jordan, Minnesota
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Quote:
I have a problem which I believe is in my quantity of magnets. I have the large stator Toshiba drive with bearings that I rewound to 27 turn single with #26 wire (green Radio shack) "Star" config. and put 8 n45 magnets in the bell N-S-N-S-N-S-N-S at 45 degree increments.
I struggled with the same question. What I found was that with 12 magnets like everyone uses, you only have the 3 "energized" motor poles directly lined up with magnets at any given time. i.e. 120 deg apart. So, when you look at other magnet counts, you'll find this also happens with a count of 6.... not 8 or 10. I am not a real math guy, but it's a trig. thing. I layed down some lines in CAD to verify this is true.

I hope I explained this well enough.... it's easy to see on paper, kinda tough to describe in words.

Wayne
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Old Jan 19, 2004, 11:42 AM
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I thought so, I started scratching my head and thinking about it and figured a 6 or 12 count would be better. I used 8 instead of 12 because allelectronics shorted me 2 magnets so I only have 10 instead of 12. I am going to order some from engconcepts today so I can make a bigger "bell" to fit thicker magnets. Thanks for the help!
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Old Jan 19, 2004, 11:43 AM
Hi Wattage Electrics - Cool
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Jordan, Minnesota
Joined Jan 2004
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So to take magnet count a step further.... I think any of the following magnets counts would work.

3 magents = 120 deg apart
6 magents = 60 deg
12 magnets = 30 deg
24 magnets = 15 deg
48 magnets = 7.5 deg

Wayne
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Old Jan 19, 2004, 11:56 AM
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Stockbridge, Georgia, United States
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Roger Gantz

I know next to nothing about electronics. I do have a good multi meter (but have not much of a clue on how to use it) I know what the D/C, A/C, Ohm's, Continuity settings are, but sometimes not sure how to use the OHM's.

What is R?

Thanks
Glenn
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