Study on the Effect of Metal Particles on the Surface Trap Characteristics of Different Insulating Materials

In HVDC equipment, the surface insulation characteristics of insulators are threatened by the irregular movement of micrometer metal particles. As one of the important means to characterize the insulating properties of materials, surface trap characteristics can effectively characterize the influence of micrometer metal particles on the insulating properties of insulating materials. In this paper, a new measurement method of surface potential attenuation is used to investigate the effect of different amounts of metal particles on the trap characteristics of three different insulating materials: epoxy resin, silicon nitride ceramics, and alumina ceramics. The results show that the initial potential and potential decay rate of silicon nitride ceramics and alumina ceramics are higher than those of epoxy resin materials, and the density of the shallow trap central level is higher than that of the deep trap central level. When fewer metal particles are attached to the surface of the insulating material, the surface potential decay rate decreases, the trap density of the shallow trap center decreases, and the density of the deep trap center increases. When more metal particles are attached, the surface potential rate increases, the trap level of the shallow trap center increases, and the deep trap center density decreases. The conclusions of this paper are of guiding significance for the surface charge suppression of DC gas wall bushing insulators.