Impulse Breakdown Characteristics of Coated Electrodes in SF6 Gas

The authors investigated the impulse breakdown characteristics of coated high-voltage electrodes in SF6 gas with a varying nonuniform factor, electrode area, and coating material. From the viewpoint of the relation between breakdown stress and the stressed electrode area, it was clarified that with coated electrodes, breakdown voltage remains, with an increasing electrode area, nearly at the theoretically estimated level for SF6 gas breakdown without showing any decrease due to the area effect (in contrast to bare electrodes). Moreover, it was also recognized that repeated breakdown characteristics of coated electrodes differed depending on the coating materials.