TWO METHODS OF ON-LINE STATOR WINDING AND CORE DIAGNOSTICS FOR LARGE ELECTRIC MACHINES

摘要

This paper presents two on-line diagnostic methods which can identify the loosening in different support structure elements of electric machine stators and overheating in stator windings with water cooling systems. The method of detecting the loosening is based on a spectrum vibration analysis applied to measurements provided at several points of a machine frame under operational conditions. When stator elements become loose, the mechanical shock vibration processes appear. Quantitative differences of the spectra with the presence and the absence of shock vibration processes is estimated by cepstrum analysis. Examples of practical applications to the large motors and generators are presented within this paper. The detection of overheating is based on measuring stator bar temperatures by standard RTDs at several loads. Special statistical processing of these temperatures is used to detect overheating. Examples of revealing these defects at large generators are presented.