The Accumulation Characteristic for Surface Charge on the GIL three-pillar insulator under AC Voltage

The research on surface charge accumulation characteristics are mainly focused on plate samples and basin insulator, and there are few reports on the surface charge accumulation characteristic on the GIL three-pillar insulator. Based on actual 550kV GIL three-pillar insulator, a three-dimensional(3D) surface charge measurement test platform utilizing the capacitive probe has been set up in this paper. The surface charge accumulation characteristic on the GIL three-pillar insulator are carried on different conditions such as voltage amplitude,test duration and surface roughness. The results show that there are surface charge accumulation phenomenon on the GIL three-pillar insulator under AC voltage. The amplitude of accumulation negative charge is larger than that of positive ones. The charge density accumulated in the pillar region was lower, while the charge density accumulated in the abdomen region was higher. With the amplitude and the duration of applied voltage increasing, the accumulated surface charge density of the insulator increases gradually. With the roughness of insulators increasing, the accumulated surface charge density of the insulator increases gradually as well. Under certain conditions, the insulator surface flashover voltage decreases by about 9.6%,with the accumulation of surface charge under AC voltage. The research results are helpful to the design optimization and maintenance of GIL three-pillar insulator.