Surface Charge Accumulation Characteristics of the DC GIL insulator in Transient Process

This paper aims to investigate the effects of the conductivity of insulating gas on the transient charge accumulation on the surface of GIL insulator under dc voltage. Firstly, we built physical field coupling model of surface charge accumulation on dc GIL insulator. Then we deduced a mathematical model to quantitatively describe the initial distribution, accumulation coefficient, variation coefficient of surface charge by the steady-state and transient calculation. We found the law of density of surface charge changing with time. It can be seen that the change of density of surface charge at point A (the intersection point between gas-solid interface and central conductor) meet the exponential law. The corresponding relationship between k (variation coefficient) and gas conductivity was shown in results. A linear model was applied to match gas conductivity and the formation rate of gas ion. When the formation rate is too small such as 5×10
^-19
S/m or too big such as 10
^-16
S/m, there will be a bigger error in the matching relation, so there was a nonlinear part in the figure. We built a mathematical modeling of the linear part. We found the law of the intensity of electric field at point A. When the conductivity of the insulating gas was higher, the intensity of electric field at point A and the potential gradient would be smaller, and the intensity of electric field at point A and the potential gradient would decrease faster with time. The work may provide theoretical basis and technical support for the design and application of dc GIL.