GE Frame 5 Gas Turbine BB#2 High vibration

GE Frame 5 gas turbine BB#2 12.69 mm/sec high vibration on 50% 7MW load while BB1 8.59 mm/sec & BB2 2.55mm/sec are running normal.
what could be happen?
 
First, please check the information you provided. It's unclear and confusing. Usually GT Bearing #1 has two sensors, usually identified as BB1 and BB2. GT Bearing #2 has two sensors, usually identified as BB4 and BB5 (BB3 is usually skipped for two bearing machines like Frame 5s). You mention BB#2 and then BB1 and BB2.

Second, has anyone gone out to the unit and felt any excessive vibration around either the #1 bearing area or the #2 bearing area?

Third, does the unit have redundant sensors on both the #1 and #2 bearings? If so, what are they reading? If it's only a single sensor of a redundant pair and no human has felt excessive vibration at either end of the turbine shaft then the problem is most likely something is amiss with the sensor with the "excessive" reading (temperature problems; loose sensor bolt(s); loose connector; loose wire termination along the circuit between the sensor and the turbine control system; a problem with that partiular sensor input channel (though if it was a GE Mark* turbine control system it would likely have a Diagnostic Alarm to indicate a problem with the input channel).

Which brings us to fourth, what turbine control system is being used on the turbine?

Fifth, does the turbine have Bently-Nevada proximity sensors on the turbine bearings? If so, what are they indicating (both ends of the turbine)?
 
WTF?
ControlsGuy25

Sorry for insufficient provided data, This is GE Frame5 gas turbine running 16MW generator and its have 3 bearings BB#1, BB#2 & BB#3 each bearing installed one seismic vertical probe. now its running on 7MW load and BB#2 vibration is alarming upto 12.69 mm/sec while BB#1 8.59 mm/sec & BB#3 2.55mm/sec are running normal.
BB#1 Axial compressor suction side
BB#2 Axial compressor exhaust side
BB#3 Turbine exhaust side
Turbine control system is GE MARK5 & there is no BNC panel.
 
WTF?
ControlsGuy25

Sorry for insufficient provided data, This is GE Frame5 gas turbine running 16MW generator and its have 3 bearings BB#1, BB#2 & BB#3 each bearing installed one seismic vertical probe. now its running on 7MW load and BB#2 vibration is alarming upto 12.69 mm/sec while BB#1 8.59 mm/sec & BB#3 2.55mm/sec are running normal.
BB#1 Axial compressor suction side
BB#2 Axial compressor exhaust side
BB#3 Turbine exhaust side
Turbine control system is GE MARK5 & there is no BNC panel.
@TANWEER

Thank you for clarifying the issue..

Also please try to answer to @WTF? questions:

Second, has anyone gone out to the unit and felt any excessive vibration around either the #1 bearing area or the #2 bearing area?

Third, does the unit have redundant sensors on both the #1 and #2 bearings? If so, what are they reading? If it's only a single sensor of a redundant pair and no human has felt excessive vibration at either end of the turbine shaft then the problem is most likely something is amiss with the sensor with the "excessive" reading (temperature problems; loose sensor bolt(s); loose connector; loose wire termination along the circuit between the sensor and the turbine control system; a problem with that partiular sensor input channel (though if it was a GE Mark* turbine control system it would likely have a Diagnostic Alarm to indicate a problem with the input channel).

After that we will be able to add notes and try to help you as best as we can from here.
 
Thanks for clarifying. This must be a pretty old machine to have three bearings (I presume you are referring to a bearing between the axial compressor and the turbine section--please clarify if otherwise). I AM NOT singling you our, TANWEER, but this is a HUGE problem with people who think that EVERY GE-design Frame "n" is like EVERY OTHER GE-design Frame "n" heavy duty gas turbine. And the Frame 5 has been produced for more than 70 years (that's 7 decades--more than half a century). There have even been many two-shaft GE-design heavy duty gas turbines, some used for power generation but most were used for mechanical drive applications (centrifugal compressors; pumps; etc.).

So you've used some other vibration measurement sensor/equipment and it also says there is high vibration on the #2 bearing. (I presume that also means the people taking the measurements felt the vibration, also....)

If this is a single shaft machine (axial compressor and turbine section combined in a single shaft) it's likely that there is some mechanical problem with the coupling between the axial compressor and the turbine section (if they are bolted together--which was a common method of combining the two sections) OR a problem with bearing (worn; oil flow problem (could be too little or too much) OR a L.O. temperature problem or possibly a cooling and sealing air problem around the #2 bearing housing. I have only seen photos of a similar machine, and I don't exactly recall how the #2 bearing is lubricated and how the oil drain is connected to the bearing housing.

But, if you have "verified" the problem with a second vibration sensor, then it's most likely NOT a turbine control system problem but some kind of mechanical problem. AND, if there were some kind of Mark* V turbine control system problem there would most likely be some kind of Diagnostic Alarm to indicate such a problem.

What Diagnostic Alarms are present on the Mark* V when this excessive vibration is occurring?

I wish I could have been more help.

Let us know what you find, please.
 
WTF?
Thank you for your quality time
when we increase the load up to 10MW the BB#2 vibration goes down from 12mm/sec to 8mm/sec now machine is running on normal parameters, & this turbine commissioned in 1965 :D its very smooth GE Turbine.
 
Two things.

First, this forum is about automation and controls. The Mark* V will generate a Diagnostic Alarm if a vibration input channel is not working correctly. You haven’t told us what alarms (Process and Diagnostic) are present when you are experiencing this problem. But, as was written, it’s most very likely the problem is real and mechanical—NOT controls-related.

Second, WHEN DID THIS PROBLEM START? After a maintenance outage? After a trip from load? Did the problem suddenly appear, or did it gradually appear? What is the L.O, temperature now, and what was it when the the vibration wasn’t a problem? Has the ambient temperature changed since the problem started? When was the last time the machine was shut down for a maintenance outage? What mechanical work was done during the last maintenance outage? Has the machine rotor ever been replaced?

But, still—and most importantly—it’s not likely the problem is controls-related. And, sometimes you gotta crack a few bolts if you want to fix a problem you can’t identify easily.

Best of luck.
 
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