Electromagnetic and image charge effects on Metallic particle contamination in Gas Insulated Substation (GIS) or Gas Insulated Busduct (GIB)

Abstract

Gas Insulated Substations are high voltage Substations that are compact, requiring little maintenance when compared to air-insulated conventional Substations. Compressed Gas Insulated Substations (CGIS) consist basically a conductor supported on insulators inside an enclosure which is filled with sulfur hexafluoride gas (SF6). The compactness is with the use of SF6 gas, which has high dielectric strength. The voltage withstand capability of SF6 Busduct is strongly dependent on field perturbations, such as those caused by conductor surface imperfections and by conducting particle contaminants. The contaminants can be produced by abrasion between components during assembly or operations. Electrical insulation performance of compressed gas insulated Substation is adversely affected by metallic particle contaminants. Free conducting particles, depending upon their shape, size and location, may lead to serious deterioration of the dielectric strength of the system and also one of the major factors causing breakdown of the system and leading to power disruption. These particles can either be free to move in the Gas Insulated Busduct (GIB) or they may be stuck either to an energized electrode or to an enclosure surface. The presence of contamination can therefore be a problem with gas insulated substations operating at high fields.