Single-phase AC motor - winding distribution

Click For Summary

Discussion Overview

The discussion revolves around the winding distribution of a single-phase AC motor, specifically a Delco model with 32 slots and 4 poles. Participants explore the implications of coil distribution on performance, potential modifications for power increase, and the challenges associated with motor design and construction.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant questions whether there is an optimal distribution of windings among the three coils per pole or if it is primarily about widening the pole.
  • Another participant notes that the distribution of turns can vary by model and suggests that the outer coil typically has more turns to maximize copper in the field core.
  • Concerns are raised about safely increasing the motor's power without sacrificing RPM, with one participant suggesting that increasing power could lead to overheating and thermal overload.
  • A participant considers removing starter coils to add turns to running coils but expresses uncertainty about potential overheating risks.
  • Discussion includes the idea of minimizing harmonics in the electromotive force (emf) as a possible reason for winding distribution, though understanding of this concept is limited among participants.
  • Another participant questions the motivation behind modifying the motor instead of acquiring a larger one, considering the effort involved in rewinding coils.
  • One participant shares their personal motivation for rebuilding the motor, emphasizing a desire to restore it rather than discard it as junk.
  • There is a query about how to determine if the motor is rated for intermittent or continuous duty, with a preference expressed for continuous duty for efficiency reasons.

Areas of Agreement / Disagreement

Participants express varying opinions on the optimal winding distribution and the feasibility of increasing the motor's power. There is no consensus on the best approach to modifying the motor or the implications of such modifications.

Contextual Notes

Participants acknowledge limitations in their understanding of technical concepts such as harmonics and motor ratings, which may affect the discussion's depth.

Who May Find This Useful

Individuals interested in motor design, electrical engineering, or DIY projects involving motor modifications may find this discussion relevant.

Historical artifacts (tools, furniture, toys, buildings, etc.)

  • Leave as-is - don't touch

    Votes: 0 0.0%

  • Return to original state - don't touch

    Votes: 0 0.0%

  • Return to original state and use

    Votes: 0 0.0%

  • Update and use

    Votes: 1 100.0%

  • Cannibalize or integrate

    Votes: 0 0.0%

  • Recycle for raw material

    Votes: 0 0.0%

  • Other (please explain)

    Votes: 0 0.0%
  • Total voters
    1
Ergison
Messages
3
Reaction score
0
Motor: Delco - 1/4 HP - 5.3A - 1735 RPM - single-phase AC; 32 slots - 4 poles

- I have run into conflicting terminology, so I apologize for any confusion -

Each of the four poles in this motor's stator core contains three coils with two empty slots at the center for a total of eight slots per pole. Is there a perfect distribution of windings between the three coils, or is it only a matter of widening the pole? I have read that distributing the coils in a belt like this creates a more sinusoidal pattern...but...I can't find any information on a proper distribution.

Also, is there a way for me to SAFELY increase the power of the motor without sacrificing RPM?

If you can at least point me toward a good explanation, I will be quite grateful.
 
Engineering news on Phys.org
I am not an engineer so you may need to wait for someone more knowledgeable to give you a better answer. However, I did work for a company that manufactured motors very similar to the one you're asking about. I can tell you that the distribution of turns between the three coils on each pole will vary depending on the model. If your motor has an auxiliary winding then the outer large coil will usually always have a greater number of turns than the inner two. As I've said, I'm not an engineer but I would suspect that the reason for the three coils per pole is to maximize the amount of copper in the field core. The engineers seemed to love to cram as much copper in there as they could. It was a real challenge for guys like me to keep the machines from scraping the wire as it was inserted into the field core.

I don't know of any way to safely increase the power. These motors are probably already engineered for maximum output. Trying to increase it would probably just saturate the field core and lead to increased heating which would cause the thermal overload to trip more often.
 
I was afraid I might not be able to increase the power...All I can think to do is remove the starter coils and add to the running coils, bringing the motor up to speed by hand or with another motor that I can disengage. But maybe that, too, would cause it to overheat..?

It makes sense for the outer coils to have more turns because the coils in the other circuit don't pass through those slots - at least, not in this 4-pole, 32-slot motor.
I do remember a greater number of turns in the outer coil, but my counts varied between coil belts (probably my fault). Tonight I'll measure the total length of each belt and try to recreate the distribution.

I just wish I knew if there were more to those numbers than maximizing the amount of copper! I read something about minimizing harmonics in the emf, but I couldn't begin to understand any of it. Maybe I'll study that again tonight.
 
Why is there an unrelated poll attached to this thread?
 
I wondered about the poll also. I just assumed it was an error.

You are correct about the turns on the inner two coils. Since the aux winding (starter coils) do not occupy the same slot as the main outer coil, it allows for a greater number of turns on the main outer coil. If you're using the motor for intermittent duty and the motor is rated for continuous duty then you may be able to get away with boosting the power a little. But I'm curious to know why you would go to so much trouble. I know it's not easy inserting all that wire by hand. Why not just get a larger motor? Maybe the same type motor with a larger stack height?
 
I apologize for the poll; I can't seem to get rid of it. Perhaps a moderator can do that?

I'm rebuilding this motor because I found it in a pile of junk, started dissecting it, and my dad said 'Hey! That's mine! But don't bother - it's not worth it.' So...naturally, I'm trying very hard to resurrect this thing. That, and if it can be made to run it ought to - otherwise it's just another piece of junk, and we've got way too much of that around here.

How would I figure out whether the motor were rated for intermittent or continuous duty?
Continuous duty is what I'm after for the sake of efficiency.

If I can get enough power I'll put it on a wood lathe.
 
Last edited:

Similar threads

Induction motor windings, number of turns per phase and per pole
  • · Replies 2 ·
Replies
2
Views
5K
Why can't a 2 pole ac induction motor run a 6 pole induction generator
  • · Replies 4 ·
Replies
4
Views
3K
AC Single phase stator wiring help
  • · Replies 6 ·
Replies
6
Views
8K
How Can I Determine the Number of Poles in a Burnt AC Induction Motor?
  • · Replies 2 ·
Replies
2
Views
2K
Determining motor/control options to act on a spring
  • · Replies 1 ·
Replies
1
Views
2K
What is the minimum number of poles in single phase motor
  • · Replies 1 ·
Replies
1
Views
14K
Driving three phase induction motor with single phase supply
  • · Replies 3 ·
Replies
3
Views
2K
Why Choose Higher Pole Motors If Lower Pole Motors Can Achieve Similar HP?
  • · Replies 1 ·
Replies
1
Views
7K
Single phase Induction motor Design
  • · Replies 3 ·
Replies
3
Views
3K
Induction motor generator capacitor
  • · Replies 45 ·
2
Replies
45
Views
17K