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Noknroll

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Reply with quote  #31 
Gary
Yes, EDM in AC induction non vfd
See Petes link to the old site on pg 1 of this topic
My 2nd reply in that thread has pics
stace1g

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Reply with quote  #32 
Thanks Oli/Nok
Vibe-Rater

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Reply with quote  #33 
There's also a good ABB technical paper.  See attached.  Also attached an EDM bearing I called a few months ago. Wasn't really going to fail catastrophically but operators kept reporting noise in this area. rgds

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jpeg Bearing damage after 16 months.jpg (95.41 KB, 11 views)

 
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pdf 124100191_ABB_Technical_Guide_5.pdf (1.39 MB, 18 views)

MachDiag

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Reply with quote  #34 

Some outer races on two different double row, spherical roller bearings (SKF 22230, cylindrical bore, split pillow block housings).  These each came off some energy flywheel machines (2 different units), each having a 14,000 lb flywheel rotor.  Both the motor/generator and flywheel had grounding brushes installed.  None of the motor/generators (with insulated bearing housings) on these machines have known to have had any EDM bearing damage occur.   
  
I've seen plenty of deep groove ball bearings with fluting before, but this is the first time I've seen it on double row spherical bearings.  I thought it strange how a single row had gotten so much abuse compared to the other row. 

1a.jpg 10.6 G's peak to peak waveform  

  4d.jpg 20.6 G's peak to peak waveform

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VibGuy~5

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Reply with quote  #35 
We bought some Aegis shaft voltage measuring equipment recently. Basically an oscilloscope that shows the voltage waveform (build/discharge) from the motor shaft. We have a few 250 kW motors with insulated shields as opposed to bearings, so it should be interesting to see the differences between these and other motors with insulated bearings.
Anybody here tried out this tech?
James.

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Reply with quote  #36 
Hi VibGuy~5, yes I've hired this before and as long as you can put the shaft riding brush on the unguarded rotating shaft it works a treat. Just follow the simple set up manual and you will have no problems.
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