Impending Generator Failure
Impending Generator Failure
(OP)
Have a 12MW utility-parallel, enclosed generator that is suddenly producing a very significant "hot electrical" smell.
All instruments are reporting "normal" values for temperature, current, voltage, etc. No protection has operated.
Did winding resistance and insulation resistance on both windings, plus surge on the stator. The only unexplainable reading is the rotor resistance was about 25% low based on nameplate voltage and current. The two caveats are the resistance is NOT temperature corrected, and this is a 28 pole machine so one shorted pole would not account for that much difference.
The rotor is basically inaccessible. You can barely even see it, so there's no way to do pole-drop.
Any suggestions at all for further testing? Something is going to fail here, and I have no idea how else to find it.
All instruments are reporting "normal" values for temperature, current, voltage, etc. No protection has operated.
Did winding resistance and insulation resistance on both windings, plus surge on the stator. The only unexplainable reading is the rotor resistance was about 25% low based on nameplate voltage and current. The two caveats are the resistance is NOT temperature corrected, and this is a 28 pole machine so one shorted pole would not account for that much difference.
The rotor is basically inaccessible. You can barely even see it, so there's no way to do pole-drop.
Any suggestions at all for further testing? Something is going to fail here, and I have no idea how else to find it.





RE: Impending Generator Failure
Muthu
www.edison.co.in
RE: Impending Generator Failure
RE: Impending Generator Failure
Keith Cress
kcress - http://www.flaminsystems.com
RE: Impending Generator Failure
RE: Impending Generator Failure
Better if you can mark the poles uniquely, and sort of sync the frame rate to rotation.
The idea is to get a slow motion video, in focus and not blurred, of the poles passing, and marked in such a way that you can identify which is which.
There will be some challenges.
Mike Halloran
Pembroke Pines, FL, USA
RE: Impending Generator Failure
RE: Impending Generator Failure
Also, to be clear, I'm looking at the rotor because it's the only test that is slightly "off" but I have no solid evidence that's the location of the fault.
We've discussed infrared, but you can't see the stator, and can barely see parts of the rotor: It's another case of just because we can't see s problem doesn't mean it isn't there.
RE: Impending Generator Failure
I have a FLIR thermal camera and I'd scream at a 1 degree temp difference but I'm not sure how fast its framerate is so I'm not sure how it would perform on your spinning rotor. Be nice if you could borrow one and try it. You might see one rotor bar that's significantly hotter.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Impending Generator Failure
Have a look at this paper from GE: https://powergen.gepower.com/content/dam/gepower-p...
In my opinion the Mk. 1 human eyeball and an oscilloscope is still the best way to observe the trace, but some manufacturers have added a computer and attempted to use software diagnostics to recognise a shorted turn as an online monitoring system. I remain unconvinced about this based on the ones I've seen, but one day someone will get it right.