GIS barriers: application of field computation strategies to switchgear

SF/sub 6/ insulated GIS substations have been used in transmission systems worldwide for more than 25 years. Service reliability of this equipment is of paramount importance. This presentation briefly reviews the application of EM field computation strategies in support of GIS designs. Major factors influencing the insulation design and in-service dielectric behaviour and reliability of epoxy resin support insulation are considered. The selection of safe operating stresses and the importance of this and related parameters to achieving high levels of in-service reliability are discussed. The importance of dielectric design/performance databases is also considered together with an indication of the extremely high level of in-service reliability which can be achieved by adopting prudent field design criteria and effective commissioning. The relevant importance of epoxy support insulation formulation, shape, surface finish, system level of cleanliness, operating pressures, importance of surface charging phenomena and in-service high technology monitoring strategies are also touched upon. The designs presented provide valuable case study illustrations.