Killing randomly distributed surface charges and guarding surface insulation performance under thermal gradient: temperature dependent adaptive interface conductivity

Abstract

Abstract The thermal gradient formed along the spacer radial direction during DC GIL operation significantly aggravates the surface charge accumulation, especially the randomly distributed surface charges, inducing local electric field distortion and further leading to surface flashover. In this study, the idea of temperature dependent adaptive interface conductivity (TDIC) method is proposed to eliminate the randomly distributed surface charges as well as significantly promote surface insulation performance under thermal gradient. The experimental results show that randomly distributed charges are obviously observed on pristine spacer surface under room temperature. The thermal gradient can seriously enlarge the distribution range of randomly distributed charges. However, for the spacers with temperature dependent adaptive interface conductivity realized by TiO2/epoxy coating, nearly no randomly distributed charges are found under thermal gradient. Moreover, the existence of thermal gradient dramatically suppresses the overall surface charges on coated spacers. It is interesting that the flashover voltage decreases by a large margin on pristine spacer under thermal gradient application whereas it always keeps at a high value on coated spacer even under large thermal gradient. A theoretical model is proposed to reveal the regulation mechanism of temperature‐dependent adaptive conductivity coating on surface flashover performance under thermal gradient. We believe this study could inspire novel idea for the optimal design of DC GIL spacer under thermal gradient.

Affiliated Institutions

• China University of Petroleum, East China CN
• Hefei University of Technology CN
• Tianjin University CN

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