Large Synchronous Machines Diagnosis Based on Air-Gap and Stray Fluxes - An Overview

This paper gives an overview on large synchronous machines diagnosis based on air-gap flux and stray flux. An investigation that proved the ability of air-gap flux measurement to detect most common defects encountered in large synchronous machines in general and hydro-generators in particular is first presented. Then, the proof of concept of diagnosis of induction machines based on stray flux and acoustic noise measurement by commercial sensors is presented. The investigation was then extended to synchronous machines that use stray flux for their diagnosis.