Vibrations on Generator Coupling end bearing

[npower0073]

On site we have a 324 hydrogen cooled generator 270MW of GE. Recently we started receiving proximity vibration alarms from displaycement sensors located on the bearing of coupling end. The increase is picked up by both of the sensors (each sensor is located in 90 degrees distance from the other). The time that this happens is when the machine works in base a load for some hours and afterwards it is instructed to minimum load. During the transition we receive the alarm. Can you please advise? Alarm is at 0,15mm and usual readings are at 0,08 mm.

 

[sms]

There is a lot of things that could cause that. Do you know what the vibration frequencies are? Orbit shape? Shaft centerline position? Vibration on the other bearings in the train?

What is the condenser vacuume doing at this time? Could be the turbine exhaust is heating up due to improper vacuume, and as a result you are misaligning between the turbine and generator.

I would suggest an in depth vibration analysis...

"Why don't you knock it off with them negative waves? Why don't you dig how beautiful it is out here? Why don't you say something righteous and hopeful for a change?" Oddball, "Kelly's Heros" 1970

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