The Improvement of Flashover Characteristics with Field Grading CCTO Coating for GIL Spacer

In gas insulated transmission line (GIL), the insulation failure often occurs due to flashover accidents induced by surface electric field distortion. An emerging coating with field grading CCTO is proposed to improve the electric field distribution and flashover voltage. In this paper, the CCTO coating with different layer thickness was fabricated on the spacer surface by magnetron sputtering. The electrical properties of emerging spacer under different voltage forms were studied through simulation and experiments. The results indicate that CCTO coating can significantly improve the electric field distribution, and the optimized effect is more obvious with the increase of sputtering time. The flashover voltage results show that the sputtered spacers have great insulation performance under AC voltage, DC voltage and polarity reversal voltage.