Author Topic: Two Pole Four Pole Stator Difference  (Read 5204 times)

Offline Ivan

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Two Pole Four Pole Stator Difference
« on: February 24, 2014, 05:41:59 AM »
This is the tag for a 20 HP 2 pole motor, in the next pics you can see the difference in back iron.  The 2 pole motor has more back iron.
:<bs:



Here is pics of two 20 hp motors, same frames, this motor has a lot more back iron ( 2 pole 3450 rpm) (the iron from bottom of slot to case) and only 36 slot (bigger slots) hoping this motor will handle saturation better.  Will wind this motor and test it against mizs 20 hp motor.
:Dd":


Here is the pic of Mizs 20 hp motor (this was a 4 pole motor)



:co<:  If you bought just one or two extra can goods a week and donated to a food bank   Nobody would go hungry.

Offline mizlplix

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Re: Two Pole Four Pole Difference
« Reply #1 on: February 25, 2014, 12:42:36 AM »
What we have is two seemingly identical 20 HP motors.  In reality, one is 2 pole and one is 4 pole.  Each has different backiron. 

The 2 pole  has a smaller rotor and more backiron than the 4 pole motor does.

We are going to wind both identically and dyno to see the result  of the backiron difference.

As a bonus, the dyno controller has an open VCL in it. The HPEV vcl is removed to allow all parameters to be changed. It lets us change things like slip and to set other parameters past the HEPV programmed controllers. 

This way, we can get a operational determination of using a 2 pole motor over a 4 pole motor and which is better if at all.

Miz

   
1930 Ford Speedster, AC50, full manual powerglide, 6.14gears, 38-130AH CALBs.

Offline HighHopes

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Re: Two Pole Four Pole Difference
« Reply #2 on: March 07, 2014, 09:04:04 PM »
this is a really important test i am really eager to see your results. 
makes me sad in a way because my 10HP motor i bought is 8 pole original, so... ya.

Offline mizlplix

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Re: Two Pole Four Pole Difference
« Reply #3 on: March 07, 2014, 11:06:28 PM »
8 poles.........(that is considered a small family in Warsaw)......LOL

Miz

Do u have any pics of it apart?
1930 Ford Speedster, AC50, full manual powerglide, 6.14gears, 38-130AH CALBs.

Offline piotrsko

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Re: Two Pole Four Pole Difference
« Reply #4 on: March 08, 2014, 08:44:21 AM »
HEY  that wasn't funny.  8 poles is a NORMAl size family

Offline mizlplix

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Re: Two Pole Four Pole Difference
« Reply #5 on: March 09, 2014, 04:19:56 PM »
(At least I didn't do my other one...."If you had 8 poles at least you could screw in a light bulb....")

Miz
1930 Ford Speedster, AC50, full manual powerglide, 6.14gears, 38-130AH CALBs.

Offline Horizon

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Re: Two Pole Four Pole Stator Difference
« Reply #6 on: May 22, 2014, 07:23:20 PM »
I'd like to ask about the stator poles, in one thread i see that:

1. "The number of stator slots must be divisible by the number of phases (3)-PLUS-be also divisible by the number of poles.(4)"  I.E.: 24 ,36, 48, 60, 72...ETC. Any in-between numbers will not work..."

And in another thread I have read:

2. "Your fundamental problem is this:
24 slots..........
24/4 poles=6   
24 /3 phases = 8 

BUT 8/6 presents a problem  so some slots must be skipped somewhere......."

Which of the two is correct? If no.2 is correct than a 24 pole stator cant be used for 4 poles without skipping slots. Is there a typo in the no.1 suggestion?
I'm sorry if I bother anybody asking questions but I found these contradictory answers and I think this is fundamental while looking at picking a motor.


Offline Ivan

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Re: Two Pole Four Pole Stator Difference
« Reply #7 on: May 23, 2014, 03:28:12 AM »
I don't follow your numbers   :dD(:

Simple, don't care about the phases, each phase just stacks one ontop of the other..

Since we allways want 4 poles evenly spaced (the first phase).

So, a 24 slot stator.

24 slot divide by 4 poles equals 6 slots per pole.

Each phase would use 16 slots (half a slot) and we have 24 slots or 48 half slots, 3 phases times 16 slots equals 48.

Each pole would have two coils.

The first pole slots 1 2  and  5 6
The second pole, slots 7 8 and 11 12
Third pole  slots  13 14 and 17 18
Forth pole  slots  19 20 and 23 24

Each slot would have 2 phases in it.

:co<:  If you bought just one or two extra can goods a week and donated to a food bank   Nobody would go hungry.

Offline Horizon

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Re: Two Pole Four Pole Stator Difference
« Reply #8 on: May 24, 2014, 08:39:31 AM »
Thanks for the reply Ivan, I was quoting mizplix from two different threads and I was confused by the different answers.
So in the end it seems that when selecting a motor for rewind, the number of stator slots should be dividable by 3 and also dividable by 4.
I didn't thought of dividing the slots (making them half slots as you refer).
Btw I found a Siemens 15 HP 3000 rpm or so, long length, unknown number of stator slots, if only I had the money... :(

Offline HighHopes

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Re: Two Pole Four Pole Stator Difference
« Reply #9 on: May 28, 2014, 04:29:38 PM »
horizon, check out your city's motor rewind shop.  call them up and ask if they have any used motors, can be pretty much any poor condition except with no short-circuit in the rotor.  every city has at least one of these shops.  once they tell you they have a whole rack to chose from, then you can be more picky .. looking for 2-pole and hopefully inverter rated.  used motors are fine, i think, cause you are going to rewind & re-insulate when following ivan's method.. so only other thing you have to do is replace the bearings.  then the motor is pretty much like new after that anyway.

i picked up a 10HP induction motor like this for $100.

Offline Horizon

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Re: Two Pole Four Pole Stator Difference
« Reply #10 on: May 29, 2014, 03:07:49 AM »
HighHopes surely I won't buy a new motor then rewind it :D, I was planing to go to the rewind shops, there are some quite/many rewind shops here but I don't think they will be cheaper than the junkyards i visited. However I was thinking, wasnt there a chance of getting tricked into buying a stator with a mismatched rotor? Maybe they had some rotor that was shorted and inserted another rotor (off of a lower HP rated motor but the same length or maybe a 4 pole stator and a rotor that was from a 2 pole stator) and that way I would end with bad efficiency, ultra low rpm, the nameplate of the stator wouldn't mean anything and so on. However things didnt work out as I planned so I'm being stopped with all this right now but I hope Ill be back on track next week. Also I wanted to ask, when changing the bearings, should I look for some that are insulation rated or some sort of, so they wont short the electricity from the rotor to the stator? Or the oil that is in the bearing takes care of the electricity not being conducted?

Offline Ivan

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Re: Two Pole Four Pole Stator Difference
« Reply #11 on: May 29, 2014, 04:00:41 AM »
Also I wanted to ask, when changing the bearings, should I look for some that are insulation rated or some sort of, so they wont short the electricity from the rotor to the stator? Or the oil that is in the bearing takes care of the electricity not being conducted?

  :mA<:   Don't have clue what you are talking about,  a bearing is a bearing, sealed bearings, so you don't have to grease them.

The only conduction is a magnetic field, don't make this sound so hard..
:co<:  If you bought just one or two extra can goods a week and donated to a food bank   Nobody would go hungry.

Offline Horizon

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Re: Two Pole Four Pole Stator Difference
« Reply #12 on: June 01, 2014, 04:45:38 PM »
Ok, theoretically speaking, let's say every phase has it's equal share in the stator (one third of the slots), is it possible to wind a stator 4 pole but in a way that the phases won't go one on top of the other?

Offline Ivan

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Re: Two Pole Four Pole Stator Difference
« Reply #13 on: June 01, 2014, 04:49:41 PM »
Ok, let's say every phase has it's equal share in the stator (one third of the slots), is it possible to wind a stator 4 pole but in a way that the phases won't go one on top of the other?

 :HH*:  Impossible   what like each phase have its own slots,  you would have too many slots
                                the slots would have to be real small.
:co<:  If you bought just one or two extra can goods a week and donated to a food bank   Nobody would go hungry.

Offline Horizon

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Re: Two Pole Four Pole Stator Difference
« Reply #14 on: June 01, 2014, 05:10:18 PM »
Well for example a 12 slot stator. Just simple for the illustration.
A would start on 1 and finish on 4 slot
B would start on 5 and finish on 8 slot
C would start on 9 and finish on 12 slot
Then the delta connections  AS+BF; BS+CF; CS+AF.  :Wo^: