The numerical model of surface charge accumulation was established based on a 252 kV basin type insulator. The influence of applied voltage and gas pressure on charge accumulation is analyzed. The simulation results show that both positive and negative ions near the insulator decreases with the increase of voltage, but the surface charge density increases and the growth rate gradually decreases. With the increase of SF₆ gas pressure, the concentration of positive and negative ions in GIL would also increase and the concentration distribution of positive and negative ions would be more uniform. When the gas pressure ranges from 0.1 MPa to 0.7 MPa, the charge density on insulator surface increases. And the surface charge density shows a trend of gradual saturation.

basin insulator, gas insulated transmission lines, high voltage direct current, surface charge