Anyone please comment. A expander (turbine Like) suddenly increased and exceeds its alarm value 55um measured by proximity probe. A low frequency appearing @ 0.175X. Please see attachment.

Generator is driven by a gearbox reduction from 27500 to 3600 CPM. The drive shaft is an integral assembly of pinion (gear) and impeller expander (function same as turbine)

Expander was started at around 10.30hrs in the morning. Both the HSS & LSS Axial position readings have gradually come back to within the acceptable range. However, impeller end of the HSS radial vibration readings (VE-3804/3805) went high, one probe reaching alert level while other above danger level. It remains high at the same level for around 4hours and of a sudden it return back to normal level of 24/26microns(both the radial probes) from 62 /47 microns(please refer below trend). During this time one discrete frequency component of around 0.188RPM suddenly disappears. Although this frequency was quite appearing previous years, this time its amplitude was higher, reaching above the danger level.

Please feel to make comments

best regards

mersky

Hi elmer where is the attachment?

Try to operate the auxilary lube oil pump with the main pump and watch the vibration trend.

regards
mahmood

If you have the polar plots of the vibration analysis i can review it and provide a quick disposition. thanks
Regards,
Dave