750hp Wound Rotor Induction Motor

[GreenTwin]

I got a call one day in 2015, "We are having problems with our pump motors; can you come take a look?".

"Sure" I said.
Got down there and the four pump motors were 110 years old.

"We want to replace them with new motors" they said.

"No way" I said, "a new high rpm motor and gearbox will not last like these".

So I had to figure out how to get these old wound-rotor induction motors rebuilt.

We found a fantastic rebuilt shop, and now they are like new.

I just ran across this video of starting up one of the rebuilt motors.

What a cool sound they make when they start.

Many confuse these motors with synchronous motors, but these are induction motors, and do have slip.

 

[GreenTwin]

The stator at the rewind shop.

Motors run at a non-standard 6KV level (I forget the exact number).

Rotor is visible in the background in the second photo.

 

[GreenTwin]

Nameplate

 

[Bazzer]

The stator at the rewind shop.

Motors run at a non-standard 6KV level (I forget the exact number).

Rotor is visible in the background in the second photo.


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I have worked on some powerful electric motors (upto 11Kv and 10,000 Hp) but never a motor with such a large diameter and short stator/rotor length.

 

[trlvn]

Awesome video! Are the motor bearings babbit? How are they lubricated?

Craig

 

[GreenTwin]

Awesome video! Are the motor bearings babbit? How are they lubricated?

Craig

Yes, they are very large babbit bearings, with a floating copper ring that drags oil up to the top of the bearing as the shaft rotates.
Crude but very effective and foolproof bearing oiling method.

It took five people to lift off one of the bearing caps, and they were struggling.
The bearings are basically designed to operate continuously almost forever at rated load.

 

[oldCB]

The stator at the rewind shop.

Motors run at a non-standard 6KV level (I forget the exact number).

Rotor is visible in the background in the second photo.


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So very cool, my cousin used to rewind motors always found it fascinating, I was surprised whilst using my Father-in-laws old ridgid shop vac as an extractor while cleaning the carpet in a Satorn I rescued form a junkyard, it suddenly sped up, then slowed down and began emitting a litte smoke before I could yank the plug on it. I'm only trying to fix it because I'm a cheap Hunky from the Burgh but more importantly I really do miss him, and figure He's getting a kick out of how much time I spent getting it apart because 1 nut was frozen on the shaft due to the taper!! LOL!