Charge Accumulation Characteristics on Insulator Surface Under Temperature Gradients in DC GIS

The surface charge accumulation behaviors in DC GIS are significantly influenced by temperature gradients. This study constructed a platform for measuring surface charge under temperature gradients, and evaluated the surface charge distribution in SF6 environment under various temperature gradients. When the temperature of high voltage conductor grew from 20°C to 100°C, the average homo-charge density dropped from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4.14 \mu \mathrm{C} / \mathrm{m}^{2}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.1 \mu \mathrm{C} / \mathrm{m}^{2}$</tex>, whereas the average hetero-charge density rose from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.99 \mu \mathrm{C} / \mathrm{m}^{2}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2.86 \mu \mathrm{C} / \mathrm{m}^{2}$</tex>. Through multiphysics field simulation, the predominant pathway of homocharge accumulation changed from surface to bulk conduction as the temperature gradient boosted. Moreover, the electric field around the ground electrode significantly increased due to the large temperature gradient, which generated a considerable increase in the surface conduction current and hetero-charge density.