Study on Lifting Characteristics of Spherical Metal Particles and Air Gap Discharge Caused by Motion in DC GIL

Metal particle pollution problem limits the development of DC GIL. Metal particles are more active under DC voltage, which affects the insulation safety of equipment. In this paper, the metal particle motion observation platform is built. Under DC voltage, the influence of the shape, quantity and voltage polarity of the metal particles on the lifting of the particles in the spherical parallel plate electrode is studied. The experiments, the motion of metal particles and air gap discharge caused by particles, are taken to analyze the influence of the particle material, shape and voltage polarity on the motion characteristics and the air gap discharge breakdown. The particle lifting characteristics, the correlation characteristics of the particle motion and the air gap discharge breakdown are obtained. The typical particle motion behavior and air gap breakdown characteristics are analyzed in the microscopic point. The results show that the lifting voltage of spherical metal particles increases with the increase of particle density and radius, and the quantity has little effect on the lifting voltage of spherical metal particles. The polarity of the DC voltage does not affect the lifting voltage amplitude of metal particles. Spherical metal particles bounce back inelastically with the electrode, and the particle recovery coefficient is measured through experimental collisions. The air gap breakdown caused by metal particles can be divided into static particle breakdown and particle motion breakdown. The study has a guiding significance for taking measures to suppress the initiation of metal particles and revealing the mechanism of air gap discharge caused by particles.