A gas-insulated substation (GIS) is a high voltage substation in which the major conducting structures are contained within a sealed environment with a dielectric gas known as SF6, or sulfur hexafluoride gas as the insulating medium. In comparison, a conventional (AIS) or Air-Insulated Substation, uses atmospheric air as the dielectric gas medium, as these types of substations primarily consist of outdoor facilities.
Gas insulated substation (GIS) consists of components where active parts on high voltage potential are located in the middle of the aluminum alloy pipes and held in this location by epoxide resin insulators. The pipes are filled in with insulating gas and have earth potential. The GIS consists of typical HV components such as disconnectors, CBs, busbars, and voltage and current transducers. GIS can save up to 90% of space compared with air-insulated substations. It is particularly suitable for indoor and outdoor applications.
The technology type of GIS is defined by:
The insulation gas:
SF6
SF6 mixture with N2
SF6 free
The phase arrangement:
one phase per pipe
three phases per pipe
The voltage level
Application type:
indoor
outdoor