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Old Feb 01, 2008, 05:04 PM
Flying motor mount master
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San Jose, California, United States
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Valid LRK wind?

Folks

I tried this one last nite and it doesn't seem to want to work with any ESC that I have tried. It even spiked to 59A!!!! with a noload test. Yikes!!!

I will have to admit I'm trying this one with 10poles. I also carefully checked for any shorts and found none.

This is kinda like "Find Waldo".

B
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Old Feb 01, 2008, 06:02 PM
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landru's Avatar
Vancouver, Canada
Joined Mar 2003
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Hi Bryan,

Do you have the opposing teeth wound the wrong way?

http://www.bavaria-direct.co.za/models/files/lrk.gif

Andrew
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Old Feb 01, 2008, 07:09 PM
Flying motor mount master
fly_boy99's Avatar
San Jose, California, United States
Joined Oct 2004
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Andrew

As you can see from the pic that it starts left,right,left on the star termination end it should be right,left,right. But if you look at the pic the start and endpoints for the winding are the same.

This is why I posted it and the pic must just be labeled wrong. I don't see how this can work for any lrk wind let alone mine.

B
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Old Feb 01, 2008, 07:36 PM
It's a Great Day to Fly
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http://translate.google.com/translat...de/Schema.html

I did one with the five gram motor that was ABCABC. This diagram looks like AbCaBc, good according to the link for 10 or 14 magnet poles.

Len
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Last edited by LenBFP; Feb 01, 2008 at 07:50 PM.
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Old Feb 01, 2008, 10:05 PM
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Bryan,

Yes, something seems odd here.

If we look carefully at the scheme diagram you posted, we see that when tooth no.1 is magnetized as North, the diametrically opposite tooth (no.7) is also magnetized as North. Trace the current flow and the direction of winding in any phase to see the outward facing polarity of opposing teeth.

Like-polarity opposed teeth are not typical of LRK as far as I know. Indeed, like you, I can't see how the scheme can work as drawn with 10 or 14 magnets.

Note that an odd number of permanent magnet pole pairs (such as the 5 or 7 poles pairs in LRK) always results in opposite permanent magnet polarity across the diameter of the bell.

I do understand that the intent of the posted scheme is to allow a more convenient wye termination. However, why the deviation from the standard magnetization?

Andrew
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Last edited by landru; Feb 01, 2008 at 11:19 PM. Reason: Concision
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Old Feb 01, 2008, 11:57 PM
Dave North
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The diagram seems like a standard whitebread LRK wind, which has worked fine every time I did it. How many turns, what stator size etc? Delta or Wye?


Dave
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Old Feb 01, 2008, 11:59 PM
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I noticed the same thing a while back looking at that winding diagram on some website. The opposing teeth are the same pole when magnetized, so it can't work unless you have 2, 4, 8 or 12 magnets.
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Old Feb 02, 2008, 12:03 AM
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Amherst, VA
Joined Jun 2006
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Quote:
Originally Posted by fly_boy99
Folks

I tried this one last nite and it doesn't seem to want to work with any ESC that I have tried. It even spiked to 59A!!!! with a noload test. Yikes!!!

I will have to admit I'm trying this one with 10poles. I also carefully checked for any shorts and found none.

This is kinda like "Find Waldo".

B
10 magnets should work. Did you make sure your magnets were N S N S N S all the way around? If you wound it correctly for LRK (which it looks like you have) the only thing I can think of is the magnets not alternating properly.
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Old Feb 02, 2008, 12:06 AM
Dave North
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A photo would be particularly helpful. Mondo macro, of course.


Dave
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Old Feb 02, 2008, 12:37 AM
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Look very carefully at the last two LRK diagrams on his page: http://translate.google.com/translat...de/Schema.html . Pay attention to the current flow and the 'hand' of the windings.

In one case the opposing teeth are like poles. In the other case the opposing teeth are unlike poles. Both cases cannot be correct.

I think Bryan has discovered the contradiction. He used the scheme from the bottom diagram.
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Old Feb 02, 2008, 12:39 AM
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I wonder if it will run with 12 or 16 poles.
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Old Feb 02, 2008, 12:48 AM
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Columbia, Missouri
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Quote:
Originally Posted by landru
I wonder if it will run with 12 poles.

I am drawing it out here, and I don't think it would work. The N poles would line up over every magnetized tooth at the same time, so it would have to be wound and terminated in a manner that kept all energized teeth the same polarity.

Maybe it would work, but I am not seeing it yet.
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Old Feb 02, 2008, 12:51 AM
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Quote:
Originally Posted by johnrobholmes
...it would have to be wound and terminated in a manner that kept all energized teeth the same polarity...
Yes, agreed. Would the unwound teeth be magnetized as the unlike poles, and thus allow the motor to run? Starting problems?
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Old Feb 02, 2008, 12:59 AM
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Bryan, you haven't unwound that stator yet, have you?
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Old Feb 02, 2008, 02:29 AM
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It looks like it is terminated improperly. I could be wrong. I usually am
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