in 2008 we run the T/G with minimal vibration problem (plots jul2008 bode, trend/rpm, polar, orbit,scl)and we attained the rated speed of 3,600 rpm.
in dec.2009 we run again the unit but after low speed heat soak (1000rpm) unit tripped with high vib at gen brg3. plots dec2009 bode, trend/rpm, polar orbit.

need comment pls.

Bacman_104a.doc (154 KB, 34 downloads) runup and shutdown data

another set data

Bacman_2001.doc (141 KB, 26 downloads) turning gear to low speed heat soak

machine configuration

Bacman_config.doc (28 KB, 27 downloads) prox location/descrip

Hopefully some like Bill F and Steven S will weigh in some some thoughts.

These is a lot of info not provided and you do have issues from procedure to possibly lubrication. When was setup and who documented?

Your monitoring of slow-roll via prox probes was taking out the bow prior to engaging to bring to speed? A 1000 RPM may not be optimal; consult with your OEM or technical data from mfg.

In the meantime, you may want to be as helpful as you can by providing more info so that some or many can assist or advise. Calling a remote shot by a consultant is not likely to get a commitment with limited knowledge and no first-hand knowledge.

I will take a stab to start....

It seems to me that the second post (3:30), you show a polar plot but you hold at ~1000 rpm (which also seems to be running on the first critical - not a great idea). You hold this speed for heat soak but notice that the phase is changing with time (even though speed is constant). Maybe my thinking is all wrong, but at constant speed, your phase should be constant (although I realize phase does change rather quickly around criticals).
But notice after 2 hour soak, the amplitude quickly starts to increase. Is it possible you are experiencing a rub???

1. I question the choice to soak at what appears to be first critical and
2. Is there any time domain data to show other evidence of rubbing??
Regards
Jim P

Did this machine just sit idle for the long time period between cuts of data or was some work performed?

John from PA

thanks a lot guys for the comments.

Sam,
the slow roll data and the eccentricity was ok prior to turbine rolling as shown in the bode plot up to 1000 rpm.

ivibr8,

the heat soak was from the OEM instruction, pls. notice the 2008 and 2009 data from bode plot. I can only conclude that before bringing the unit/rotor to 2,300rpm high speed heat soak from 1000 rpm low speed heat soak. the amplitude and phase should be constant/ stabilized. as you mentioned, although there is the first critical just after the 1000 rpm heat soak. But my data shows the gen,brg.3 has very low amp/phase.thus we decide to run to 2,300 rpm but unit tripped due to high vib. What time domain data u lyk me to post? and what other plot formats to verify the rub incident?

John P.A.

Yeah. The T/G were idle. There was a repair work performed on the turbine rotor and some steam pipings.The gen was checked for the oil deflector labyrinth seal clearance(oil seal)(hydrogen cooled gen.) but we only run the unit with air as provided by the OEM.

sirs, more comment pls.

bode plot

rdy.doc (86 KB, 15 downloads)

sorry, not oil seal but the Seal Oil. This is the oil system for the generator. the air gap of the gen was thoroughly checked and was within the oem tolerance.only the Seal Oil deflector was adjusted/worked to the tolerance/limit clearance.