Capacitive and inductive 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. Among various causes, air-gap anomalies may arise due to shaft eccentricity, which will be dealt with in this work. A prototype machine was specially manufactured allowing the deformation of rotor and stator yokes, as well as the radial displacement of its shaft position. These features permit assessment of the performance of the sensors under study. The developed sensors are of the capacitive and inductive types, placed in the wedges of the stator slot openings, and symmetrically distributed along the air-gap surface.