直流GIL中盆式绝缘子表面电荷分布特性研究

The surface charge on insulating materials is an important factor to trigger surface flashover. In order to study the characteristics of surface charge accumulation on spacer in GIL, a surface charge experimental setup as well as measurement system under high gas pressure was built, which realized the fully automatic measurement of surface potential of spacer in a sealed chamber. A pair of coaxial electrodes was applied to model the real GIL. Surface potential distribution on a downsized cone-type spacer was measured by an electrostatic probe in 0.5MPa SF ₆ gas under DC voltage. According to the surface potential distribution, the actual charge density distribution of the spacer surface was computed by the charge inverse algorithm with high resolution, and the influence of electrostatic probe was considered in this algorithm. The results show that the surface charge distribution can be divided into two kinds of different patterns. The first class are homo-charges presenting a symmetrical distribution. The second one are hetero-charges showing a streak distribution, and singular polar charges displaying a random distribution on spacer surface. It is concluded that the gas conductivity, the spacer surface conductivity and the spacer volume conductivity contribute to the three different charge distribution patterns. The surface roughness can inhibit the second class of charge accumulation but cannot inhibit the first type charge accumulation. The results could provide the guidance for design of DC GIL.