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Effect of lubrication oil on alternator winding

Effect of lubrication oil on alternator winding

Effect of lubrication oil on alternator winding

(OP)
Hi
During normal operation, oil was dripping below our alternator 45 MW 11 kV. The oil comes from the bearing. During shutdown, a hydraulic pipe was replaced. Now still some oil is dripping.
Can the oil cause damage in the rotor and stator winding? Any other negative impact?










RE: Effect of lubrication oil on alternator winding

Yes, oil will damage the winding insulation and is a fire hazard. Wipe off the surface oil where accessible with clean cloth. Do cryogenic cleaning of the winding. And more importantly, stop the oil ingress into the winding.

Muthu
www.edison.co.in

RE: Effect of lubrication oil on alternator winding

Oil in/on windings; Not good.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

RE: Effect of lubrication oil on alternator winding

You must couple time at every shoutdown of generator do same things like Edison said. High temperature od winding make condition to came out some oil residual from windings insulation.

RE: Effect of lubrication oil on alternator winding

After a recent rewind of a generator, we were doing testing, and the first time the new rotor had been energized.

No one expected smoke to come from the generator (except for the testing contractor). The smoke came from the oil used in completing the rewinding, and as the first time the coils had been heated up the oil smoked off.

RE: Effect of lubrication oil on alternator winding

Yes. "Greasing of the Windings" can case many different types of problems (some short term, some long term) but ultimately can result in failure if the issue is severe or compounded by other issues or operational conditions:

1) It can affect heat shedding in the windings, attract dirt and block ventilation holes resulting in the stator running hotter and decreased lifespan.
2) It can act as a medium to attract and hold conductive particles (such as bits of bearing or other conductive material). This can result in "surface PD" or discharge on the winding between adjacent phases or phase to ground.
3) It can literally "grease" the windings in the slot section. The windings are under immense fluxuating force. The grease can act as a lubricant and help loosen up the windings over time.

*I had a machine a few years ago that got heavily grease and we ending up removing it from service to overhaul. We had PD monitoring on the machine and could monitor the severity of the tracking. The machine did survive for a long period of time after the initial contamination; however, upon disassembly we discovered heavy tracking, semi con layer deterioration on the end windings where the grading tape was and many loose wedges.

Take the machine apart. Do some electrical testing to access stator condition then start cleaning and rinsing using a light solvent. Once you're happy with it give it another clean an rinse and check for any residual oil using your finger, clean cotton gloves and q-tips in the ventilation holes, and don't use anything like steam or a pressure washer. Then bake it out and retest to make sure you didn't do any damage in the cleaning...

RE: Effect of lubrication oil on alternator winding

Effect of lubrication oil on alternator winding:

It will take a gamble of time to cause an "effect" on the winding if it's not eventually remedied, fixed, etc.

Unfortunately, the 11,000 volts makes it very easy for all that potential to track everywhere on the apparatus.

The [negative impact] is mostly economic if it's not corrected.

In a perfect world, the alternator is removed from service and cleaned.

Yes, oil can be wiped off, wiped down, cleaned off and any number of other quick fix solutions.
Those peeking in on this thread... likely know all of the above is a "Band-Aid" approach.

The apparatus needs to be thoroughly cleaned and oven dried in order to allow a peaceful nights rest.

John

RE: Effect of lubrication oil on alternator winding

First, fix the flippin' leak.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

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