Electric motor repair book

Something I have been looking into. I found a book that explains how to do your own rewind.

Electric Motor Repair by Robert Rosenberg

http://campkahler.com/files/ElectricMotorRepair_Illustrations_StudyQuestions.pdf

Here is a catalog for supplies.

https://www.essexbrownell.com/uploadedFiles/Content/Products/MR Supplies Catalog-s.pdf

I wonder if motor shops even make money on rewinding motors. It's a labor intensive job.

ewlsey said:

I wonder if motor shops even make money on rewinding motors. It's a labor intensive job.

Click to expand...

Last time I checked around, maybe two years ago, I was flat told that I could buy a brand new 10hp three phase motor (which is what I was asking about) for less money than they'd have to charge... And I assume he meant from the manufacturer, not e-bay.

Dennis

ewlsey said:

I wonder if motor shops even make money on rewinding motors. It's a labor intensive job.

Click to expand...

Good question. Over 20Kw I'd say they do. It's not only rewinding, it's bearings, shafts, balancing etc. But small power, I doubt it's worth the trouble. I just bought a 4Kw, 4poles, 220/380V for $250 and I didn't think it was cheap. In the same time an experienced rewinder is very quick - quicker than I would dare write here. There will be some margin but not much.

rons said:

Something I have been looking into. I found a book that explains how to do your own rewind.

Electric Motor Repair by Robert Rosenberg

http://campkahler.com/files/ElectricMotorRepair_Illustrations_StudyQuestions.pdf ...

Click to expand...

What a great book! Thanks for the post.

rons said:

Something I have been looking into. I found a book that explains how to do your own rewind.

Electric Motor Repair by Robert Rosenberg

http://campkahler.com/files/ElectricMotorRepair_Illustrations_StudyQuestions.pdf

Here is a catalog for supplies.

https://www.essexbrownell.com/uploadedFiles/Content/Products/MR Supplies Catalog-s.pdf

Click to expand...

Thanks for the supplies link. Didn't know there was such a thing-have been piecing together supplies from various suppliers, so it's nice to have a single place to buy everything.

The Rosenberg book is copyrighted, BTW. Not sure how CampKahler justifies posting it online. It's a classic and can be had on the used market for $30 or so. Later editions are a LOT pricier.

https://www.bookfinder.com/search/?...0a-c%20and%20d-c%20motors%20and%20controllers

neilho said:

The Rosenberg book is copyrighted, BTW. Not sure how CampKahler justifies posting it online.

Click to expand...

There appears to be a second edition, which is not online. If you feel guilt then don't look at the book online and buy a copy.

AlexO said:

..... In the same time an experienced rewinder is very quick - quicker than I would dare write here. There will be some margin but not much.

Click to expand...

In most of those books they show doing up custom coils, so you can assemble just like the factory, prewound coils that are put into the slots. That goes pretty fast, and the winding of coils can be done over nails in a board. In some of the automated factories, putting in the coils takes literally a few seconds.

Of course, hand placement CAN have better interwinding insulation, and much less issue with corona, the corona voltage may be much higher than any requirements..

rons said:

There appears to be a second edition, which is not online. If you feel guilt then don't look at the book online and buy a copy.

Click to expand...

Got a bit of a hair trigger, mister? I don't recall mentioning any personal guilt and don't have any. How about you?

I have the third edition, bought 25 years ago. It's a fine book.

That book is in the time window when the copyright would have expired unless the owner specifically renewed it. Most didn't, but you'd have to check to be sure.

neilho said:

Got a bit of a hair trigger, mister? I don't recall mentioning any personal guilt and don't have any. How about you?

I have the third edition, bought 25 years ago. It's a fine book.

Click to expand...

No trigger just a question. How many expert rewinds have you accomplished in the last 25 years?

Armature Winding-1920-pdf

Armature winding and motor repair; practical information and data covering winding and reconnectig procedure for direct and alternating current machines, compiled for electrical men responsible for the operation and repair of motors and generators in industrial plants and for repairmen and armature winders in electrical repair shops : Braymer, Daniel Harvey, 1885-1932 : Free Download & Streaming : Internet Archive

John

I had work at a motor rewind shop in the 90's. Just to rewind a simple 3 phase motor with no machine work was $300. I'm talking 5hp or less. A factory can kick out a motor winding in minutes when making hundreds. But a one off repair takes hours. I don't miss the stress of trying to get customers motor repaired in a timely manner. But I do miss the problem solving. We worked on everything from locomotive traction motors to small DC motors. I do wish I'd had taken pictures back then. One of my favorite motors that came in was about 8' tall and 1' deep winding (stator). The rotor coils (windings) were the size of Harley jugs mounted on the shaft (rotor). The motor was only about 250hp at 200rpm. All the connections on the stator windings had been wiped out when the motor over spun rpm. The brake had failed and dropped the load down a 800' deep mine shaft. The customer figured it was spinning at a couple thousand rpm before copper started flying out. One of our retirees came in and re engineered what the connections should be. He loved every minute making all drawings for the connections. It only took two men a month to repair and what fun to watch the test run. Got to love slow HP.

The green thing to do is to get the rewind. At least the rewind shop explains it like that.

A three phase motor has a lot more copper and I would not want to start with one of those. A single phase motor is the place to start.