New low-cost fiber optic accelerometer system for stator winding monitoring of hydroelectric generating machines

Abstract

A new fiber optic accelerometer system for stator winding simultaneous multi-point vibration monitoring of hydroelectric generating sets is presented. It is composed of as many sensor heads as points to be monitored, an optical channel and a processing unit distant from the sensing area, which is exposed to strong electromagnetic interference. The evaluation scheme is based on an intensity modulation and differential detection technique so that the measure is not influenced by external perturbations. The system is able to measure accelerations ranging from 30 to 450 Hz, with a maximum amplitude of 200 m/s2 RMS. Experimental results for the previous prototypes developed are showed. This sensor is intended to be integrated in a new complex system aimed to reach the goals of instantaneous protection, real time detection and evaluation of defects, failures and malfunctions in the above mentioned machines.