Torsional Vibration, in Rotordynamic System, Identified by Monitoring Gearbox Behaviour

Abstract

Nowadays the wide diffusion of the electrical machines, used for power generation, or as driver/helper in Oil&Gas applications, have amplified the problematic related to train torsional excitation. The standard instrumentation installed on the train does not permit to monitor and analyze this kind of stress; therefore to define criteria to screen torsional alternating stress by lateral vibrations becomes extremely important. This paper describes the experience achieved by the authors in the study of rotordynamic behavior of some geared train with the goal to define a methodology to analyze torsional stresses adopting industrial proximity probes (installed in the gear) or a non intrusive measurement system (optical probes). In order to confirm the last technology, an additional classic strain gage torsional measurement has been adopted obtaining similar results. An extensive part of this paper is dedicated to illustrate several test campaigns performed in different site where customers highlighted abnormal vibration levels. Finally, a wide description of data post processing and consequent conclusions are offered.