Multi-parameter Fibre Optic Sensing System for Remote Condition and Operation Monitoring of Gearbox Bearings in Rack and Pinion Jacking Systems

Abstract

In a world where more than ever “time is moneyâ€, there is a continuous push for new technologies that enable condition and operation monitoring of critical industrial equipment in often inaccessible locations and very harsh environments, thus minimising the need for corrective actions, down-times and at the same time providing better insights about their operation. In this paper, we demonstrate the technical feasibility and the inherent advantages of Fiber Bragg Grating (FBG) based fiber optic systems to remotely sense, in real-time, multiple performance parameters of critical gearbox bearings inside rack and pinion jacking systems. The bearing condition and operation monitoring system jointly developed by Smart Fibres and SKF includes numerous FBG-based optical sensors to monitor temperature and both dynamic and static strain, which were deployed in various points inside the outer race of the sensing bearing. Smart Fibres’ SmartScan 04 FBG interrogator acquired real-time measurements of all the aforementioned parameters, which thanks to SKF’s data analysis expertise and its knowledge of bearings and loads were combined and transformed into meaningful insights about the condition and operation of the gearbox’s bearing and the jacking system as a whole. An innovative method to instrument rolling element bearings was put in practice during this project. For the gearbox bearing instrumentation on this jacking system, two FBG arrays, each containing 15 strain sensors and 1 temperature sensor were fixed in a groove machined on the outer race of the bearing’s structure. This allowed us to measure real-time temperature, rotational speed and dynamic/static loads at multiple points around the bearing’s structure. Not only did this provide a more direct indication of the bearing’s condition than conventional strain gauge based load cells, but it also provided valuable information about the alignment and loading of the bearing both in running as well as in stand-still conditions. Some of the intrinsic characteristics of fiber optic sensors make them particularly suitable for this type of application. Complete immunity to electromagnetic interference enabled our sensors