AAAWELDER

3 Phase Motor 


Resurrecting An Old Workhorse 



The Hunt Begins: 

We arrived at the recycling center early that morning but, the hunt was a bit disappointing because any 3 phase motor we could locate, required a fork truck to lift it. I finally asked one of the workers where they kept a 3 phase motor I could wrestle back to my truck. He turned and pointed to a huge cardboard box sitting in a corner of the shed. Still eager to find a suitable electric motor, I began to rumage through the contents. 

The surface was covered with electric motor parts: stators, rotors, castings and, slightly buried in one corner was a 3 phase motor I was pretty sure I could wrestle to my vehicle. After I liberated the motor from the box, I could hear water sloshing inside the motor. I used my Ohmmeter to check the continuity of the windings. I then checked for opens or shorts across the windings and to the case. The electric motor checked out OK, so I bought it. 



The Internal Inspection: 

Removing the end caps and the rotor from the motor revealed some sludge and surface rust. Examination of the stator proved that the enamel on the copper windings was in excellent shape. Aside from being covered in rust dust, the overall integrity of this 3 phase motor was intact making the selection of this electric motor a good choice. 


3 phase motor 1    3 phase motor 2    3 phase motor 3


The rotor on the other hand had suffered some major wear and tear. The rear bearing, I presume, was a recent replacement because, it was tight and freewheeling. The front bearing was completely trashed. There was a good 1/8th inch of lateral movement making it useless. 


Rotor    Rotor Too

Removing The Bearing: 

Split Bearing

Without an adequate press to remove the bearing, I opted to cut the bearing free using a cutwheel on the grinder and some very steady nerves. The cutwheel must not contact the shaft in any way. The slightest nick will create a stress point that torque will find. Think of scored glass with pressure applied. This bearing came off without incident. 

Replacing The Bearing: 

Cleaned Rotor


I purchased a new bearing from McMaster-Carr  that fit perfectly. A little spit and polish and the rotor was ready for another tour of duty. 

Preassembly

I took one extra step in reviving this old motor, I soaked the stator windings with a thin varnish to help the enamel on the wires to maintain its' integrity, a little assurance just in case I missed a flaw. 

New Duds For An Old Soldier: 

New Coat    New Coat Too


After cleaning off as much scale and scum as I could, I gave this old motor a brand new suit. The final step in this process is to turn the key: Will this motor run like a scalded dog or, will my efforts end in a puff of smoke? 

Applying Power: 

3 phase motor run    3 phase motor running

I read somewhere on the net that a guy ran a 3 phase motor off of single phase a.c. using a rope to start it like a lawnmower. I put that info to the test and, sure enough, the 3 phase motor started on the first pull and, though you can't tell from the photo, the 3 phase motor is running on 110v A.C. 

All I need now is a prime mover to drive it............... 









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Last Updated - 09/29/2009
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