Motor rewinding video. Not getting the translation for the phase difference.

[rons]

Induction Motor Rewinding 36 Slots 3 Phase 6 Pole With Diagram_FULL_HD - YouTube

At time 4:37 the equation that produces "4". That would be the number of stator slots to skip for another pole winding for a different phase.

Not hard to draw a diagram of a stator circle with 36 slots. Then arrange a bunch of semi-circles about the circle. There will be three layers
of these semi-circles which represent the windings. The phase difference is 4 slots. Having some trouble understanding the equation.

It looks easy to do a rewind on a 3 phase 6 pole motor (1750 rpm). Just wind 18 loose coils about some dowels on a board. Insert them and connect some wires.
The hard part is finding the supplies like stator liners, varnish, etc.

 

[Phil in Montana]

I have rewound motors all my life... this is the poorest vid I have seen. First be a copycat...what comes out goes back in. Take data before you strip the frame. It is not hard to find the supplies if you are doing this all the time, just hard to find supplies in small amounts. If you have a way to ship varnish I have lots, just a maj fight to ship. And your form will be 6 dowels not 4 for winding. and only the coils for 1 pole group not 4...Phil

 

[rons]

Ok, I figured out that the equation:

(120 * 6)/180 = 4

It's a ratio of the next phase position in a half cycle. Multiplied by the distance between coils. ? There sure are a bunch of motor repair videos on youtube.
Some of the people have bare feet.

 

[jim rozen]

...
Some of the people have bare feet.

How *else* would they be able to stamp the windings down into the slots?

 

[EmGo]

Some of the people have bare feet.

10 chars

 

[johnoder]

There is a 72 (865 RPM and 10 HP) slot here if some one wants to play. Its only about 400 Lbs, from Westinghouse about 1917

Free for pick up

 

[rons]

I have rewound motors all my life... this is the poorest vid I have seen. First be a copycat...what comes out goes back in. Take data before you strip the frame. It is not hard to find the supplies if you are doing this all the time, just hard to find supplies in small amounts. If you have a way to ship varnish I have lots, just a maj fight to ship. And your form will be 6 dowels not 4 for winding. and only the coils for 1 pole group not 4...Phil

When the supply guy says I can sell you 500 or this or 500 feet of that the message is clear.

If you run across a winding video that is in English and the place is not a dirt floor, let us know.

 

[johnrobholmes]

Calculating the slot span for any motor can be done by dividing slots by poles and then winding to that full pitch if possible, or the next lowest whole number.

36/6 = 6. Wires in slot one and 6 (1-6 coil span), 4 empty in between. There is a lot of different ways to actually wind 3 phase though, so follow the old pattern and pay attention to the entry and exit points, coil direction, and if coils are series or parallel.

 

[johnrobholmes]

It looks easy to do a rewind on a 3 phase 6 pole motor (1750 rpm). Just wind 18 loose coils about some dowels on a board. Insert them and connect some wires.

The 36 slot is electrically the same thing. If it's wound with 18 coils it is "single layer" and the coils will not share slots with other coils but be otherwise identical to the 18/6 motor wound in double layer.

If wound with 36 coils it would be "double layer" and each coil would share the slot with another. Would also have half the turns per coil so that final phase resistance is the same as single layer.

With tricky winding patterns for shorter coil connections and the potential of lower end turn height due to half the turns in each coil, it is possible to wind a double layer with slightly lower terminal resistance.

But as mentioned, just copy what is being replaced. That's the easiest method.

 

[rons]

Hope I did it right.

 

[eKretz]

Best approach is to do what Phil said. I've rewound 5 motors now from old fans and other stuff. I baked them in the grill to burn off varnish, then unwound them, counting coils (and winding direction) in each slot and jumps between stator slots. Pretty easy to put things back like they were.

 

[johnrobholmes]

Be careful baking stators in a non controlled environment. The laminations are insulated from each other and if that is compromised it increases eddy losses and no load current goes up. Always best to bake below 220f or simply slice the old coil ends off and pull the bundles out.

 

[eKretz]

Be careful baking stators in a non controlled environment. The laminations are insulated from each other and if that is compromised it increases eddy losses and no load current goes up. Always best to bake below 220f or simply slice the old coil ends off and pull the bundles out.

I replaced the insulation. Used very thin insulating paper between the laminations.

 

[JST]

The insulation is usually just oxidation and maybe some varnish. The voltage is very low, and it does not take a lot of insulation. Baking does not hurt oxidation.

I've never heard of using paper of any sort between laminations in a transformer.

 

[eKretz]

The insulation is usually just oxidation and maybe some varnish. The voltage is very low, and it does not take a lot of insulation. Baking does not hurt oxidation.

I've never heard of using paper of any sort between laminations in a transformer.

I did a bunch of reading on the subject when I was starting the first one. Very thin paper (maybe not actually paper, but similar) is one option. Oxidation and varnish are usually OEM methods. On very old motors from what I've read there are bound to be rubbed through and shorted areas between laminations, especially after a burnout. Most of the motors I did were almost a hundred years old from antique fans and such.

 

[Phil in Montana]

I have rewound 1000s of motors and transformers, I have never seen any form of insulation between the laminations, only oxidation or varnish. We would burn the core out at 800f, sand blast the slots very carefully. then replace the coils.The baking temp of the varnish was 275f..Phil...

 

[hvnlymachining]

I do the Machining for a motor rebuild shop that rebuilds dozens of motors per month. They use a kiln to burn out stators, I was told they burn at around 800°F. When they finish, the varnish, paint and leftover grease are all just ash powder that wipes off. ( Up to 500 HP fits in their oven generally)

All are eddy current tested before leaving the shop. ( So I'm told)

After watching their process I wouldn't worry much about the burnout, I'd be more interested in looking for arcing or impact damage and the like, where plates may make "weld" contact.

And make sure the bearing journals are in good shape!

 

[Phil in Montana]

It ruins your day when a winding would short out in the core, all the arcy sparky would have to be ground out and the lams un welded... hours of hard 4 letter words...Phil