Study of Electrostatic Motion Behavior and Inhibition of Metallic Particles in GIS/GIL

The most frequent insulation defect appears to be the presence of small amounts of spherical, linear, and other shapes of micro metallic particles in Gas Insulated Switchgear (GIS) and Gas Insulated Transmission Line (GIL). It poses a major risk for partial discharge if the metallic particles travel to the location with a high field strength. The study to inhibit the movement of metal particles and thus solve the issue of metallic particle contamination is the key technical challenge to effectively improve the insulation strength. In this paper, we present a mathematical-physical model applicable to the real structure with complex electric field and various types of particles using the finite element method (FEM) and the differential element method (DEM). This study shows that the asymmetry of the electrostatic force caused by the asymmetry of the particle shape is the main cause of the complex motion behavior. The model can predict several unique occurrences, including the one-sided lifting of longer linear particles, and our experiments have confirmed these predictions. The method of dielectric coating for particle motion inhibition is investigated, and a significant inhibition effect is observed as the lift-off voltage of the particles is dramatically increased.