I have a Solar Titan 130 Gas Turbine. It's a 2 Shaft Gas Turbine.
1st Shaft - Gas Producer Rotor - Consists of Axial Compressor and 2 Stage Gas Turbine. Air Intake End of this rotor is connected through a spline coupling to the accessory drive gearbox. Please see attached layout image.
2nd Shaft - Power Turbine Rotor - 2 Stage Gas Turbine Discs providing mechanical drive to the Centrifugal Gas Compressor
All the radial bearings are fitted with X & Y proximity probes.
Slow Roll response for Bearing 1Y is indicating 30 Microns whereas Slow Roll response for Bearing 1X is 8 Microns. -1X component is present throughout the slow Roll Speed.
Orbits for Bearing 1 are highly elliptical.
Shaft centerline plots show abnormal movement of Shaft Centre within Bearing 1. SCL Plots indicate downward movement of shaft center as soon as the rotor starts turning. Then coming up slowly with increase in rotor speed.
Waterfall and Cascade Plots indicate presence of -1X Component throughout slow roll and operating Speed Range.
Steady state vibration amplitudes are 25 to 30 Microns pp.
What could cause this kind of behavior? Why the high slow roll response is showing up on 1 probe only? I would appreciate any thoughts on the possible reasons for this behavior.