Over hanging portion 2

[friend81]

Is there any relation between the overhanging portion(length) & efficiency or life cycle of a motor.

For example an motor with a less overhanging portion will be having a better efficiency than the one with a large overhanging portion?.

 

[MikeHalloran]

An overhung load will affect the bearing life, but not the efficiency.

Some motors are intended for direct drive, or some such phrase indicating that there is essentially no radial load, and in the interest of economy use relatively small bearings.

Motors that are intended for use with belts, chains or gears are so marked, at least in the catalog, and have relatively sturdy bearings. Somewhere in the data sheet you should find a rating for the allowed 'chain pull' or belt tension, and its allowable location on the shaft.



Mike Halloran
Pembroke Pines, FL, USA

 

[edison123]

I think the OP is asking about motor winding overhang (end winding) lengths.

Yes, all other things being equal, the winding with shorter overhang will have better efficiency (lower copper loss)since currents in overhang do not do useful work.

*Nothing exists except atoms and empty space; everything else is just an opinion*

 

[MikeHalloran]

You're probably right, and I understand what you mean by overhang.

But that brings up a question:

Given the lengths to which motor manufacturers will go to save pennies on bearings and mechanical parts, why would they spend the extra money for copper to build a motor with a nonzero overhang? Is there some advantage to it?



Mike Halloran
Pembroke Pines, FL, USA

 

[aolalde]

The coil extension is defined by the span, wire size, turns, slots and bore diameter. It can not be reduced to extremes were the coils are jammed.
Reduced coil head extensions reduce the winding resistance but the heat sink function is reduced too, compromising the heat exchange or cooling of the winding.

 

[electricpete]

There was a great article on coil forming in electrical apparatus magazine. I have saved that hardcopy.

On the web, the provide only a brief excerpt, fwiw:

http://www.barks.com/2006/11-06feat.html

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[friend81]

thank you all for your expertise replies

 

[Skogsgurra]

I have also found that motors with lots of "overhang" have more capacitive coupling between winding and rotor. That creates higher a voltage across bearings and is a potential risk for premature bearing failure through EDM. Not exactly what the OP asked for, but related to overhang.

Gunnar Englund

http://www.gke.org

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