Generator High Vibration
Generator High Vibration
(OP)
The generator goes into high vibration(10 mils) after being at running speed for 1/2 hour prior to synchronizing, does anyone have any ideas as to why? This is a steam turbine generator set. Vibration starts at 1 mil and goes to 10 mils quite quickly.





RE: Generator High Vibration
Was the unit just inspected and re assembled. Is the phase angle rotating when at constant speed.
Oil whip
is oil temp a little cold (or bearing elavation change during inspection. at what frequency is primary mode. Oil whip primary is near 1/2 rated speed
wiped bearing
was there a temp spike in bearing metal temp during previuos coast down.
What type of unit
If you have LP hoods, running at noload will heat the backend and cause the rub. a cooling spray nozzle could be pluged causing uneven heating
RE: Generator High Vibration
RE: Generator High Vibration
Assuming that the vibration is in the generator not the turbine:
The main question is what is the vibration frequency?
If it subsynchronous, it could be misalignment between the turbine and generator unloading the generator inboard bearing.
If it is 1X and in the generator, it could be a rub, but rubs are pretty unusual in generators. Does it happen when you flash the fiel? Could be a hot spot in the exciter. I saw one once that would go to 10 mils pp immediatly on flashing the field, even before any load was applied.
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RE: Generator High Vibration
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If we learn from our mistakes I'm getting a great education!
RE: Generator High Vibration
In either case, the rapid onset of vibration from 1 to 10 mils didn't lead me to suspect a rotor short right off due to the thermal lag mentioned by ScottyUK.
If it were 30 minutes after syncronization...............
rmw
RE: Generator High Vibration
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If we learn from our mistakes I'm getting a great education!