Quasi-smart Optical Fibre Sensor System for Real Time and Predictive Monitoring on Large Rotating Machinery

Abstract

A new optical fibre sensor system including the fibre optic transducer, the optical channel, the optoelectronic unit, and a digital data acquisition and signal processing unit (DASPU), that has been fully developed and tested, both in the laboratory and in the field, is presented in this paper. From monitoring vibration on selected places of large rotating machines, the developed system is capable of processing the acquired signals in order to extract significant information for data trend analysis, and to take correction decisions with the aid of specific programs. Fig. 1 shows a schematic view of the system. The transducer operating principle is based on a fibre optic cantilever beam without any seismic mass on it, and a differential intensity modulation scheme that minimises the errors due to intensity undesirable changes and environmental perturbations. The optical fibre accelerometer is optimised for detection of mechanical vibrations in the frequency range 0.2 - 140 Hz, provides very good stability and accuracy, and has the inherent advantages of remote fibre optic sensing and electromagnetic immunity (1).