Development of distance sensors for diagnosing air-gap anomalies in synchronous generators

This paper presents the development of distance sensors to measure air-gap irregularities in synchronous generators for diagnosing static eccentricities. Capacitive and inductive sensors were developed to measure the thickness of the air-gap between the stator and the rotor poles. In order to obtain an absolute measurement of distance, an optical fiber chromatic confocal sensor system is used as a reference for the other sensors by means of a local calibration procedure. It can be concluded that capacitive and inductive sensors developed show satisfactory and promising results of air-gap measurement.