I took the casing orbit (unfiltered ) on the generator bearing and attached herewith .First of all, the orbits of displacement , vel and accn is differing. To myunderstanding, the drive end bearing velocity orbit indicates misalignment and the non drive end bearing vel orbit indicates the Rubbing.
I could not able to diagnoise from the displacement orbits and accn orbits. Can i use the velocity orbit if not comments please.

with regards,
Gevenag

Generator_Orbits.doc (607 Kb, 43 downloads) Generator brg Unfiltered casing orbits

Were these orbits acquired by three separate and distinct measurements methods or was this an accelerometer, case mounted, and integrated to velocity and then again to displacement?

John from PA

John's point is a must know! Thinking you have installed eddy current probes, then you would only need mils displacement. Then you may wish to perform an FFT and present spectral profile data as well. If you are performing diagnostics, then I would also acquire casing data. I see no need to single or double differentiate.

I'd guess that this is one acceleration units measure integrated first to velocity and then to displacement. Assuming it is a sleeve bearing I am not sure that any of these plots have any significant value as far as diagnosis of rub or misalignment is concerned since it is not showing relative shaft movement inside the bearing.

Secondly, different measurement units are expected to be different in the way the shape looks like as two of them are frequency dependent.

These redaing are taken using acclerometer and then integrated for vel and then integarted to displacment. This bearing is a sleeve bearing. The measurements are taken on the casing.