Regulation of Surface Charge Accumulation on Epoxy Insulator by Flexible Coating under DC Voltage

Surface charge accumulation on alumina/epoxy insulator affects the safe and reliable operation of the highvoltage direct-current (HVDC) gas insulated transmission line (GIL) and gas insulated switchgear (GIS). In this paper, a flexible coating strategy was proposed to suppress the charge accumulation on the insulator, so as to optimize the electric field distribution. The insulator with multi-arc surface profile and a coaxial electrode system were designed, then surface coatings with various conductivities were deposited on the designated areas of the epoxy insulator by brushing method. The effects of flexible coating on the charge accumulation behavior of the insulator under −15, −20 and −25 kV DC voltages were studied by a kelvin type probe. The results showed that when the metallic wire was adhered on high voltage electrode, the positive charges were accumulated on the nonplanar region in the form of speckles, and the flexible coating could significantly inhibit the charge accumulation on the insulator.