Surface flashover sustained by electrostatic surface charge on epoxy resin insulator in SF6 [GIS insulators]

It has been confirmed that sufficiently high electrostatic surface charge density can sustain surface flashover when the stored surface energy released can cause further ionisation and establish a chain reaction. Therefore, in addition to the widely reported results that surface charges can aggravate the triple junction field enhancement under certain conditions, it is now clear that once triggered, surface flashover can self-propagate a long distance away from the initiation sites, resulting in unexpected and erratically low flashover voltages. The proposed self-sustained surface flashover criterion has been tested to apply for different geometries and at various SF₆ pressures. The criterion simply states that the electrostatic surface energy should be sufficient for renewed ionisation activities