The Effect of a Metal Particle on Surface Charge Accumulation Behavior of Epoxy Insulator with Zoning Coating

Epoxy insulators are widely used in Gas-Insulated Transmission Lines (GILs), playing a significant role in electrical insulation and mechanical support. The metal particles generated during the production and operation of the equipment aggravate surface charge accumulation on the insulator, causing surface flashover. Therefore, it is necessary to study the suppression strategy of charge accumulation. In this paper, a downsized disc insulator was taken as the research object to investigate the effect of zoning coating on charge suppression with the presence of a linear aluminum metal particle under negative DC voltage. The zoning coating method was achieved by painting coatings with different conductivities in three areas on the insulator surface to regulate the charge. The inhibition mechanism of zoning coating on the charge accumulation in the presence of a linear metal particle was analyzed with the assistance of numerical simulation. The results showed that negative charges were accumulated in the nonplanar region as there was no metal particle, and the existence of metal particles led to the significant accumulation of positive charge speckles in the nonplanar region. The application of zoning coating could significantly inhibit the charge accumulation in the nonplanar area of the insulator and the charge injection from the grounded electrode to reduce the charge density. Under -25 kV, the maximum charge density on the insulator with the zoning coating was 48.1% lower than that without the coating, and the inhibition effect increased by 57.9% when the metal particle was introduced. This paper provides a new way to suppress the charge accumulation on the insulator surface.