Electrostatic Attraction Mechanism of Metallic Particles

Free metallic particle defect is more harmful in gas-insulated switchgear (GIS) and gas-insulated transmission line (GIL). GIS/GIL has a compact structure and is more sensitive to inhomogeneous electric fields. Metallic particles will be attracted in the presence of the electric field, narrowing the gas gap and causing partial discharge. However, the precise mechanism of the electrostatic attraction process is not fully understood. This study shows that the induced electrification process of particles is accompanied by a photon emission phenomenon, of which the precise charge quantity can be calculated with our newly introduced apparent dielectric constant. Metallic particles are equipotential in the electrification process, and their shapes, especially the sharp edges, significantly affect the electrostatic attraction of the lift-off process. The study found that electric field distortion caused by charged metallic particles can also affect the movement of particles, noting that the inhomogeneity of the particle shape leads to inhomogeneity of the electrostatic loading, making the direct derivation of particle properties from the lift-off voltage almost impossible. The results of this work yield quantitatively reliable conclusions, and may pave the way for additional sophisticated studies on electrical simulation and engineering practice.