Development Process of Vibration Sparking Erosion on Stator Bars

Abstract

Vibration sparking can cause serious erosion and deterioration of the stator bar insulation. A circuit model of the semi-conductive layer of a stator bar is proposed to describe the parameters of VS generation and the distribution of the parasitic current along the semi-conductive layer. A simulated VS system was set up to generate VS activity. This paper investigated the development process of and deterioration levels of VS erosion on the bar surface with aging time and the factors influencing VS erosion. The results show that there were three stages in the VS development process with different sparking intensities at each stage. The resistivity of the semi-conductive layer greatly increased after VS erosion. It was found that high energy from VS can result in decomposition of the semi-conductive material and lead to damage of the groundwall insulation.