A gas-insulated substation (GIS) uses a superior dielectric gas, SF6, at moderate pressure for phase-to-phase and phase-to-ground insulation. The high voltage conductors, circuit breaker interrupters, switches, current transformers, and voltage transformers are in SF6 gas inside grounded metal enclosures. A photo of Gas Insulated Substations 420kV. The atmospheric air insulation used in a conventional, air-insulated substation (AIS) requires meters of…
