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Armature windings & comutator.

12560 Views 28 Replies 7 Participants Last post by  major
Why do some motors have a small and others large wire for winding size(dia), and a high or low number of comutator segments? Second what does the number of winding segments mean? High v/s low. :confused:
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Major,
how do you have an armature design that has a different number of Commutator bars and a different number of armature slots?
How does this work?

what advatages does this have over the same number bars and same number slots? like 49 and 49 in the GE 11?
 

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Major,
how do you have an armature design that has a different number of Commutator bars and a different number of armature slots?
How does this work?
2 coils per slot. 1 coil per comm bar. 25 slots * 2 coils/slot = 50 coils. Minus one dead (unconnected) coil = 49 coils for 49 comm bars. Dead coil keeps spacing and balance. Odd number of comm bars needed for 4 pole wave armature winding.

I had thought (never having seen one) that it was 25 slots and 75 bars, using 3 coils/slot. I think GE also makes an 11 incher using 65 slots and bars. And maybe other designs as well.

what advatages does this have over the same number bars and same number slots? like 49 and 49 in the GE 11?
Some pros and cons for each way. Existing tooling plays a big part in the choice. For high volume production, equal bars and slots are probably best, for both design and process.

major
 

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You can see.....

Warp 11 have 25 slot in armature, but 49 bar comm.

I would like to know the difference rpm and torque of each motor at same voltage and current!..
Hi Yab,

So both motors have 49 bar comms. They both use single turn armature coils and wave winding. So they would have equal Kt values for those equations in my post #9.

But, both the speed and torque equations include the term _Flux_. And we do not know the Flux values for these motors, so it is impossible to draw an accurate comparison of performance from the information at hand.

Both motors use steel although we do not know the exact type. But we could assume that the saturated (maximum) flux density would be the same. To get a ballpark comparison, measure the steel armature core diameter and stack length. From this, calculate the cylindrical surface area. For a comparative ratio between the two, just use ratio of D*L, one to the other. The larger D*L will have more Flux at saturation, meaning more torque/amp on overload.

Back down at non-overload conditions, it is much harder to draw such conclusions. The field coils turns (mmf) come into play and a host of other design features like air gap length (distance between pole face and armature surface), pole pitch, etc.

Gross estimation: Same comm bar count, same size = about the same speed torque current voltage relationships.

Regards,

major
 

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yabert i think I see from your photos...you have the one piece brush design i was told by the people at warfeild to MAKE SURE that this was upgraded to the 2 piece brush design...this would then be like the WARP 11.

Is it a big disavantage to have one big brush hold with two spring compare at 2 brush with one spring on each?
I assume the same area of brush contact (2x1 = 1x2).
 

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Is it a big disavantage to have one big brush hold with two spring compare at 2 brush with one spring on each?
I assume the same area of brush contact (2x1 = 1x2).
Hi Yab,

In a perfect world it does not matter; the contact area is equal. But :) In our world, the 2 brushes are better because they can react separately to imperfections in the commutator. This improves the life or service interval and lessens the chance of problems. And the 2 brushes may each seat a bit more quickly. But it is a bit more costly to use 2 twice as many brushes.

major
 

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In a recent AC vs DC motor thread Daniël posted up about the motors used in his awesome boat project, and Paul was able to pull up some of his photos.

That got me curious to see and read the rest of the boat thread and from there i found that Major had identified the motors as having 2 Turns per coil, and that he had actually invented and made a small fortune on this multi-layer winding back in 1979, see post here.

Now i'm curious about these winding--was there a patent on the multi-turn winding, i would be interested to read it and probably others would too.
 
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