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The basin insulator is key element of gas-insulated metal-enclosed switchgear (GIS) and transmission lines (GIL), the material properties and geometry directly affects the electric field distribution in the apparatus, further affecting its insulating properties. The insulator in operation is affected by the heating of the conductor and the external environment, and has a large temperature gradient. The dielectric constant and conductivity of the insulating material are different at different temperatures, which affects the electric field distribution. In this paper, the dielectric constant and electrical conductivity of insulating materials are measured as a function of temperature, and the factors such as the transport and diffusion of charged particles in the gas space under DC voltage and the accumulation of surface charges on insulators are considered. A temperature-coupled AC / DC electric field simulation model was established to analyze the distribution characteristics of the electric field of the basin insulator under extreme temperature conditions. This study provides a theoretical basis for the optimization and design of the insulation characteristics of GIS / GIL equipment.

Due to the serious charge accumulation at gas-solid interface, the surface flashover voltage of insulator in gas insulated equipment may be significantly reduced. In order to pursue a method inhibiting surface charge accumulation, the epoxy composites modified by nano-SiC particles were coated on the insulator surface in this paper. The thickness of coating was 300 μm, and the SiC content was 5, 7 and 10 wt%. With the help of a couple of finger-shaped electrodes, the insulators with different coatings were charged at −10 kV voltage, and then the dynamic surface potential distributions were investigated. The results showed that only positive potential appeared on the surface and it mainly distributed near the high voltage electrode. With the passage of charging time, the shrinking phenomenon of high-potential region and the expansion of low-potential region can be observed. In addition, with the increase of SiC content, the average value of surface potential decreased monotonously and the shrinking speed of high-potential region seemed to be increased. Especially when the SiC content rose to 7 and 10 wt%, the magnitude and distribution area of surface potential declined sharply from 40 to 60 min. After 60 min, the surface potential distribution of the insulator with 5 wt% SiC/Epoxy coatings nearly unchanged, whereas it remained a slight fluctuation with 7 and 10 wt% fillers. Our study indicates that the coating with nano-SiC fillers has an inhibition effect on surface charge accumulation.

In AC and DC power system, the conical insulator is an important component in gas insulated switchgear (GIS) or gas insulated transmission line (GIL) equipment. The flashover phenomenon formed on the surface of the conical insulator is the key factor determining the insulation strength of GIS/GIL equipment. Studying the influence of the structural parameters of the conical insulator on the electric field distribution along the surface under the AC and DC voltage is of great significance for increasing the flashover voltage of the insulator and improving the insulation reliability of the equipment. In this paper, the key structural parameters of the conical insulator (inclination angle and fillet radius) are taken as the research object. The electrostatic equation is used to calculate the AC electric field distribution along the surface under different structural parameters. Consider the generation, migration, diffusion, recombination of free ions in gas, and the nonlinear relationship between gas current density and electric field strength. A numerical model for the charge transport and accumulation in DC GIS/GIL is established, and the DC electric field distribution along surface under different structural parameters is calculated. According to the calculation results, the influence laws of the inclination angle and fillet radius of the conical insulator on the AC and DC electric field along the surface are obtained, and the difference of the AC and DC electric field distribution along surface is compared. The results show that under the AC voltage, the electric field strength along the surface increases as the inclination angle increases, and decreases as the fillet radius increases; Under the DC voltage, the electric field strength along the surface has different distribution patterns near the high voltage conductor and the grounding shell: the electric field strength near the high voltage conductor decreases as the increase of the inclination angle, and the electric field strength near the ground shell increases as the increase of the inclination angle; Under the DC electric field, the polarity of the accumulated charge on both sides of the conical insulator is different, the concave surface accumulates a negative charge, the convex surface accumulates a positive charge, and the concave negative charge density is 1.6 times the convex positive charge density. The surface average charge density increases as the inclination angle increases and decreases as the fillet radius increases. The conclusion of this study has reference value for guiding the design optimization of GIS/GIL conical insulator structure.