The Influence of Insulation Distance and Electric Field Component on Surface Charge Accumulation on Insulators

Surface charge accumulation is an important factor to consider in the insulation design of direct curren (DC) gas-insulated lines (GILs). The proportion of normal and tangential electric field may vary due to different insulation dimensions, leading to significant changes in the surface charge accumulation pattern. To clarify the dominant charging pathways under different insulation dimensions and electric field components, this study examines two cases: a mixed electric field distribution (Case 1) and a tangential electric field dominant distribution (Case 2). Surface charge distributions are measured, and the transition in charge accumulation modes are analyzed. The results indicate that in Case 1, positive charge accumulation is the predominant distribution pattern, with gas conduction and high voltage (HV) electrode injection being the main sources of positive charges. As the insulation distance increases, the positive charge density gradually decreases due to weakened gas conduction process. In Case 2, negative charge accumulation becomes the primary distribution pattern, primarily attributed to gas conduction. With an increase in insulation distance, the negative charge density gradually increases, mainly due to the reduced tangential electric field weakening the injection process of HV electrode.