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Old Jan 05, 2013, 08:45 PM
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tlh101's Avatar
Corpus Christi, Texas, United States
Joined Dec 2002
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Trying to figure out how many poles..............

OK, I have a Turnigy D3530/14 1100Kv. It has 12 arms on the armature, and 28 magnets.
Is it 28 poles, 12 poles, or is the "/14" the pole count?
Thanks
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Old Jan 05, 2013, 08:53 PM
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C₄H₁₀'s Avatar
United States, AK, Fairbanks
Joined Aug 2009
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28 magnets = 28 poles

12 stator arms, so it's a 12N28P configuration.

"14" probably indicates 14 turns of wire on the stator.
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Old Jan 05, 2013, 09:45 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by tlh101 View Post
OK, I have a Turnigy D3530/14 1100Kv. It has 12 arms on the armature, and 28 magnets.
Is it 28 poles, 12 poles, or is the "/14" the pole count?
Thanks
I don't think that motor has 28 magnets on it, but if it did have 28 separate magnets, that would make it a 28 pole motor. I think it has 14 magnets and is a 14 pole motor.

The 14 is probably the number turns of wire on each of the stator arms.

Jack
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Old Jan 05, 2013, 09:59 PM
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OK, I'm a dummy. It does have 14 magnets.
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Old Jan 06, 2013, 09:29 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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You're not a dummy, just learning.

By the strictest interpretation, those magnets have a pole on each end and one end is North and the other end is South. But for these motors that is the type of magnet that is necessary for the motor to work and each magnet is considered to be one pole.

The pole count is often needed for calibrating data loggers that log the motor RPM. The logger counts the passing magnets and then does the math to display the RPM.

Jack
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Old Jan 06, 2013, 10:57 AM
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Corpus Christi, Texas, United States
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No, I seriously am a dummy. I took the motor apart and actually counted 28 magnets, somehow. Then after your post, I was going to post a pic with the 28 magnets, and half of them were gone.
Forgive me, but I'm getting old.
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Old Jan 06, 2013, 01:19 PM
An itch?. Scratch build.
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South Wales U.K.
Joined Mar 2003
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If you can't see the magnets, can you relate the amount of 'cogging' when the shaft is rotated to the number of poles ?.

By 'cogging', (if that's not the right term),I mean the number of definite restrictions felt as the shaft is rotated, especially with a prop on.
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Old Jan 06, 2013, 08:16 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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It is pretty tough to count the cogging steps.

For starters the number felt and the spacing will vary with the way the motor is wound, it will vary with the motor not attached to the ESC, it will change again with it attached to the ESC, and yet again when the ESC is powered up.

But if you bind all three connectors together so that they are shorted out against each other the cogging will be evenly spaced and lighter so that is arguably the best way to try it.

There is a winding scheme generator that tells us the cogging steps for various winds too. So if you know the answer maybe you can see if you can get it right:

http://i.caendle.de/dev/test2/

If you set that up for the common 12 arm stator with 14 magnets it says it will have 84 cogging steps per rotation. Do do that

1 - click on EN for English
2 - enter 12 for Slots
3 - enter 14 for Magnetpoles
4 - choose either 1-Layer (LRK) or 2-Layer (dLRK)
5 - choose either D or Y (Delta or Wye termination)
6 - click on Compute

And you'll see the cogging steps, more useful info, and an image as to how to do the wind. Want a better motor? Take any average quality or lower motor and re-wind it yourself!

Jack
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Old Jan 07, 2013, 05:17 AM
An itch?. Scratch build.
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South Wales U.K.
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Thanks Jack, I will have a look.
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