Inhibitory Mechanism of DC GIS/GIL Ground Electrode-Coating on Charged Moving Metal Particles and Optimal Design

Metal particles in gas-insulated switchgear (GIS) and gas-insulated transmission lines (GILs) are major causes of insulation failures. Ground electrode coatings can effectively limit the movement of these particles, but theoretical research and design guidelines for optimizing such coatings are lacking. This study investigates the effectiveness of ground electrode coatings in restraining metal particle movement by characterizing particle collisions with the coating surface and developing an inversion algorithm to track particle charge, achieving less than 7% relative error. It identifies “charge inertia” as a key factor in inhibiting particle movement upon collision with the coating. The coating’s high resistance, dipole gravity, and surface adhesion work together to inhibit particle motion, preventing further lifting after particles come to rest. An equivalent model of the dual inhibition effects of GIS/GIL electrode coatings, including surface adhesion on particles and charge inhibition effect, is established. The study provides guidelines for selecting low-conductivity, high-dielectric coatings and optimizes design to balance adhesion work. Preliminary tests with polyimide coatings demonstrate an 85%–120% increase in particle lifting voltage, confirming the design’ effectiveness. These findings are critical for the engineering application of electrode coatings in GIS/GIL systems.