ANALYSIS ON AGING CONDITION OF STATOR WINDING INSULATION OF GENERATOR BASED ON THE MOMENT CHARACTERISTICS OF PARTIAL DISCHARGE

The aging mechanism of stator winding insulation of large generator is analyzed. In this paper, the dependences of skewness and kurtosis in the profile of φ-q and φ-n characteristic on aging time are investigated by means of PD measurement on model bars subjected different stresses. The skewness in the profile of φ-q characteristic changes from positive to negative with aging time, which can be considered as a reference of aging course in stator winding insulation of large generator. A new phenomena is found that the maximum number of PD pulse in the profile ofφ-n appear to be at 45°and 135°in unaged specimen, at 0°and 180°in mid-aged specimen, at 90°and 270°in high-aged specimen, which is a important information to realize aging condition in stator winding insulation of large generator.