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Author Topic: 3 phase motor winding  (Read 13840 times)
justplaying
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« on: May 03, 2006, 11:05:42 PM »

Hello,

Brand new to the group.  Wanted to know if anyone out there knows how to wind/rewind a 3 ph motor.  I know there are at least 2 configurations: "Y" and "Delta", also 9 wire ends and 12, and can be wound for 2 different voltages (240/480).  BUT, a diagram means almost nothing to me.  I need actual instructions for dummies.  The stator has 36 slots.  Step by step procedure would be best.  Any takers?

thanks,
justplaying
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rsdoran
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« Reply #1 on: May 04, 2006, 05:29:13 AM »

This page may give a simple idea of what to do; http://www.harpershaven.com/motor_rewinding.htm

The problem comes from the specifications of the motor. Motor shops have charts for different size/types of motor that offers wire size and number of turns etc. If the wrong size wire, number of turns, and type of turns (single, double etc) are not right the motor may not work as needed.

You may be able to obtain the specifications for the motor from the manufacturer.

You do realize that most motors are laminated after winding and this process requires "baking".

Since you are justplaying I answered this just in case. I also moved it to the Discussion area.
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Tell me and I forget, show me and I remember, involve me and I understand."
justplaying
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« Reply #2 on: May 04, 2006, 10:15:55 AM »

rsdoran,

  Thank you for your reply/answer to my question.  Looks like I need to change my user name.  Actually, I'm quite serious about what I'm doing.  

Thanks for the website referral.  Fortunately I am way past the dc motor winding stage.  I need to clarify:   I need instructions for Dummies for winding 3 Phase motors.  So far the hunt is still on....

jp

ps.  how do I change my username?
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Tom
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« Reply #3 on: May 04, 2006, 11:26:25 AM »

first thing to do is pull the ends of your leads hooked to the winding up and check to see how many wires in hand and what the enternal connect is. The enternal connection will be Y or delta 1 or 2 circuits on a small motor. Now burn one of your leads off and check the wire size be you get the wire with an American Standard Wire Gauge. Get the pitch this is how the coils are laided in like 1 & 8. Then coils per group. Then turns per coil. Pole * phases = groups. Groups / into slots = coils per group. You get all this when you burn the motor out to where you can strip it. You can take a air chisel and cut one end off the winding then take a old burner out of a gas water heater and hook it to a butane bottle set the sator on a couple of bricks and put a fire under it. When the stator starts to smoke you will be able to pull the windings out if its the right tempature the slot insolation will come out with the wires. Then clean the stator up with a wire brush. Now your ready to reinsolate the stator. measure your steel and leave 3/8" on each side so you can fold back about 1/8" on each end so the insulation will lock in the slots once it is in the stator. The insulation needs to be either nomex or mylar are a combination of both. Once you get the slots reinsulated your ready to make the coils. Once you get to here let us know. If there is anything here you don`t understand might be able to help the best thing to do is go to a motor rewind shop and get to be freinds with one of the winders they can walk you through it. Your going to end up at a motor shop auyway to get your material. Good Luck.
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justplaying
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« Reply #4 on: May 04, 2006, 06:29:43 PM »

Hi Tom,

  Thanks for all the great advice.  I'm also past the "stripping/burnout " stage.  Due to allergies I could n't  have done it that anyway.  So I spent a couple of difficult sessions with a wire cutter, big screwdriver, and I'm sure there was a hammer in there somewhere, along with a lot of pulling and knuckle busting.  I'm sure my arms were six inches longer after that 5 or 6 hour wrestling match/tug of war.  Doing it this way saves the insulation part of it, but it ain't easy.  
  I know I had 9 leads when I started out, but I can't remember if it was dual voltage or not, I think so.  I would prefer to rewind it this wayagain if possible.  The few motor repair places that I contacted were not overly friendly, so I don't know what's up with that.  Seems like I'm asking a question that not many know anything about.  So, for all those who are interested in helping, I am at the stage where the new wire is ready to go in.  I just need to know the looping configuration.
thanks again,
jp
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Tom
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« Reply #5 on: May 04, 2006, 08:57:42 PM »

Did you take down all the data when you stripped the motor? If not your up a creek without a paddle. You can`t guess at what goes back into the motor. If you have the data we can continue if not we`re wasteing our time?Huh
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justplaying
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« Reply #6 on: May 08, 2006, 11:41:43 AM »

Hi Tom,

  We are not wasting our time.  The wire size was #20, the speed was rated at 1725rpm.  There are 36 slots.  Those wires were so jammed in there from the factory that, with the way I took it apart it,  was more than I cared to figure out at the time. I did study it hard before tearing it apart, but couldn't make much sense of it since I couldn't see where the leads came from in relation to one another, buried as they were in the coiling. It is not important to me at this point to rewire it exactly like it was. (Doubtful by hand, anyway.)  Whether or not it matches it's 5 hp rating does not matter.  Just to be able to understand the wiring configuration and get it to turn is enough for me.  I can worry about efficiency later.
thanks,
jp
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Tom
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« Reply #7 on: May 08, 2006, 08:08:44 PM »

Let`s start with what you should have done as for as taking the data from the motor.
    1. what is the pitch_______
    2. Turns per coil
    3. wire size
    4. how many wires in hand
    5. the inturnal connection

The pitch if it is a regular wound three phase motor and has 36 slots will be 1 & 8. If it has a consequent pole winding the pitch will most likely be 1 & 8, 1 & 10, 1 & 12. All this has to be taken down and all has to be right! It`s not like a gas motor it`s not going to run with partial power. If you don`t put it back almost perfect with what it was wound with from the factory it`s not going to work right. If you just want to learn how a motor is hooked up inturnally i`ll try to draw and explain one way of doing it.
Quote
The wire size was #20
do you mean 2 # 20`s in hand? By this i mean were there say to #20 magnet wires going to #1 exturnal motor lead??
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Tom
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« Reply #8 on: May 08, 2006, 08:58:18 PM »

If it`s a regular three phase winding and a 1 circuit star. This may help you understand. If you had the winding back in your motor you would have 24 ends which is a mess! So you would straighten all the ends and as you can see on the group you decided to make #1 you would turn 1 lead out and the end of that coil group up. Then go around the hole stator like this. Now there is a little order 12 leads sticking up and 12 leads sticking out. Lets start with 1 of the wires turned out and we will # this wire 1 now look at the arrows on the groups they are head to head and tail to tail. So just because a wire is sticking out doesn`t mean anything until you choose the wire you are going to make the first motor lead and then the arrows on the groups fall into play! Here is the way the leads work A phase 1-4 7-* B phase 2-5 8-* C phase 3-6 9-* So look at the picture the power goes in on 1 pickup the end of that group and count on the wire sticking up 2,3,4 and ty the ends sticking up together and the end sticking out will be motor lead #4.Now on the leads sticking out count 5,6,7 and this wire will be motor lead #7. Now pickup the end of that coil group and count 8, 9, 10 and since 7 comes out on a star this is an inturnal star. This complete the inturnal connections for A phase. Does this make any sense? On a 12 lead motor the inturnal star is brought out as #10 motor lead. Is this what you are trying to learn?
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justplaying
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« Reply #9 on: May 08, 2006, 10:06:48 PM »

Whoooooooa, horsey!  I think I just fell off the back of the horse with that last note.  I will respond to the first one...

  Ok, a slight mistake....the wire was AWG #19.  

There could very well have been 2 in hand, but I don't remember.

You mention "pitch".  I don't know what that means.  I tried to follow the winding and as near as I would tell it came out of one slot, skipped 7 and went in the 8th.  Is this what you mean?  I couldn't understand how it was wound because the wire coming out of the slot was closest to the rotor side of the slot and when it went back in (8 slots away) it went in the side of the slot that was furthest from the rotor.  

Turns per coil?  As I said, I have no idea.   i know you can get around 36 #20's in those slots by hand.

The internal connection?  How can this be told when the other ends of the leads are buried in the epoxied winding?

I'm probably turning out to be quite a disappointment to you.  Anytime you want to stop is fine. I don't want to waste your time either, if you think it is.  For me, it's not.  I'm learning, albeit slowly.
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justplaying
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« Reply #10 on: May 08, 2006, 10:34:22 PM »

OK, for the second post...

Let's start with the first couple of sentences. ..

 You say I should have 24 ends.  For 1725-1800rpm,  that means there should be 4 poles,  or 2 coils, right? 2 coils X 2 in hand = 4.  4 X 2 ends per coil = 8  wire ends X 3 phase =  24 separate wire ends.  Is that what you mean?

jp
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Tom
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« Reply #11 on: May 09, 2006, 03:23:36 PM »

Quote
Turns per coil? As I said, I have no idea. i know you can get around 36 #20's in those slots by hand.
If the frame is 184T this could be close, it is more likely you had two #20 wire going to each motor lead. One #19 is not big enough to be a 5 hp winding from all the motors i`ve wound.
Quote
I tried to follow the winding and as near as I would tell it came out of one slot, skipped 7 and went in the 8th
So the pitch is 1 & 8. so when you lay the coils in on the first seven you just lay one side in and put a piece of insulation down so you won`t scatch the wires and leave half the coil up until you get to the eighth coil. Now both sides go into slots and you do this all the way around the motor. When you get around to the first seven coils you left up  now you will raise these up and lay the last coils under them. After the last coil bottom is in you lay the the last half of the first coils down. As your put the groups of coils in cut you a piece of insulation and put between each group of coils this is called phase paper it insulates between phases and also makes it easier to locate which ends belong to which groups of coils.
Quote
The internal connection? How can this be told when the other ends of the leads are buried in the epoxied winding?
You can heat the winding up in an oven this will make the varnish soft to where you raise the internal connections to check them. Do not heat a winding in an oven that doesn`t have a good exhaust fan as the fumes are very exsplosive and your wife will not be happy with the results!
Quote
I'm probably turning out to be quite a disappointment to you
No your the one wanting to learn and if you complete your project one of the things you will learn is to make good records because with an electric motor when your old winding is gone all you have is data to start back with.
Quote
You say I should have 24 ends. For 1725-1800rpm, that means there should be 4 poles, or 2 coils, right? 2 coils X 2 in hand = 4. 4 X 2 ends per coil = 8 wire ends X 3 phase = 24 separate wire ends. Is that what you mean?
No the formula for groups is pole * phases = groups. So 1725 rpm = 4 poles times 3 phases = 12 groups and since the stator has 36 slots divided by 12 groups = 3 coils per group and since there are 12 groups no matter how many coils per group there are only 24 ends after your winding is in. If you look at the drawing you will see each group has one lead going in and one coming out. When i say coils per group which in this case is 3 that means you would wind 1 coil with say 18 turns then go to the next coil wind 18 turns then the third and wind 18 turns and then cut your wire leaving 1 end going in and 1 lead coming out. The best way to wind this motor is to make you a jig and wind 3 coils which will equal 1 group then you let your leads face the motor and take the back end of the coil and put it through the stator and each coil has to be layed in, in the same manner. How the coils are layed in the motor is very important because if one coil is bucking the other even if you get your connection right the motor will not turn.
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justplaying
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« Reply #12 on: May 12, 2006, 09:33:49 PM »

Tom,

  Before we go any further I need to have a question answered.  Obviously you know what you are doing here with all this winding.  I have 2 goals in all this.  I want know how the motor is wound and I want to end up with an AC motor that I can control the speed of.  So, if you would, please take a quick look at this link below and tell me whether or not I am understanding this product (VFD)correctly, I would appreciate it.  Does this VFD (120V model) indeed convert single phase(in) to 3 phase(out), all by itself, or is there something more to it?

http://web6.automationdirect.com/adc/Overview/Catalog/AC_Drives_-z-_Motors/GS1_(120_-z-_230_VAC_V-z-Hz_Control)
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rsdoran
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« Reply #13 on: May 13, 2006, 12:24:57 AM »

Just to help in understanding all VFDs actually convert the incoming AC to DC, the DC is then converted to emulate an AC output. This white paper may help; http://www.patchn.com/mtrwhtpaper.htm
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justplaying
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« Reply #14 on: May 13, 2006, 09:53:19 AM »

Tom,

Thanks, for the confirmation.

 Yes, that's makes perfect sense to me....now.  AC to DC to simulated AC.  I guess the reason for my questioning was the low price of these units.  Seems to me that technology would cost more, though I am very delighted that it doesn't; as least from these people.  
  NOw I will endeavor to understand this winding even more.  My concentration is a bit divided these days, dealing with family health matters and other stress, so if you don't mind hanging in there for me I will get to the next step in this tutorial as soon as I am able.  Also, I may need to order some more wire so that may take a couple of weeks or so.
thanks,
jp
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