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Hi;
We have Kollmorgen brand servo motors at Corrugator machine. Once the bearing of a motor faulted. We replaced but after that motor could not run because drive showed multiple fault messages. We installed brand new motor and all was ok.

Today again, another motor bearing faulted. We replaced but after that it did not work. Drive showed multiple error messages.
Can anyone please put some light what happens with servo motor that after opening it doesn't work.

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Scada Supervisor
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4,758 Posts
Are you putting a pipe/iron core in the middle while you have the armature out. IIRC it has to do with field collapse.
I think it was mark shaft at 12:00,
Pull armature out while sliding in pipe.
When reinserting install armature in same position while sliding pipe out.

@paulengr can tell you more.
 

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You have to manually set the positioning. I don't know how they do it, but used a servo guy that would set them for us after service or rewind. Since all servos seem different from manufacturer to manufacturer he had documentation he accumulated over many years.
Without him we could not work on servo motors.
There are other guys here that are very good with servos. I hope one of them can help.
 

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Chief Flunky
Field Service Engineer
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3,781 Posts
Lots of ways a shop can mess it up. It’s a motor and usually an integral encoder. DC is the worst…many more ways to mess it up. When you reassemble a DC motor even the number and type of shims (magnetic or nonmagnetic) and the order can mess up a motor. There is a reason that DC motor rebuilds cost ten times more.

I’d say the biggest one though for servo motors is that motor shops usually don’t have any way to test the encoders. The best they do is blindly wire them up, hoping it’s right. Those that have a test rig can’t possibly have the myriad of connectors out there and are testing for perhaps one of the three electrical designs, and aren’t set up to do it with an oscilloscope. So it’s kind of asking for the impossible and encoders are frequently an issue.
 

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Chief Flunky
Field Service Engineer
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3,781 Posts
There is no issue in wiring.

Probably the issue is in encoder adjustment.
All servos work pretty similar. Usually the encoder is so good that you can just count pulses and it always knows where it’s at. This works EXCEPT when you install a motor in an unknown position. There is a command in all servo controllers to “home” or “reset” to reset the pulse position counters. Before using it you need to position the machine in a specific, known position. Often it involves manually or automatically positioning the system at a specific spot such as up against a mechanical stop or with a cylinder fully retracted/extended or moving until a sensor such as a photo eye triggers. If you never rotate more than one full turn the Z input can work, too (manually turn until Z triggers). You can often see this in action if it is automatic. Many automatic systems slowly move the servo motors in velocity mode (speed only) only very slowly until they reach an external limit then zero/reset themselves.

Reset information is machine specific…however the machine builder designed it. It is not something the servo controller or motor company can help with unless they designed and installed the servo. Sometimes it is obvious such as when the machine creeps into a starting position on power up (does it itself) but on many machines you have to do manual positioning (with or without power) then either push a manual reset button or do some other sequence.
 

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Hi
I tried to adjust the resolver as hit and trial. With no load, motor runs well but with load it runs but after sometime resolver feedback error appears.
you may be off on the resolver by just one click, or similar
try one more very small adjustment one way, if it gets worse, go the other way
 
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