Gas Insulated Substation (GIS) Electrical Power System

Gas Insulated Substations

A gas insulated substation (GIS) is a high voltage substation in which the major structures are contained in a sealed environment with sulfur hexafluoride gas as the insulating medium. GIS technology originated in Japan, where there was a substantial need to develop technology to make substations as compact as possible. The clearance required for phase to phase and phase to ground for all equipment is much lower than that required in an air insulated substation; the total space required for a GIS is 10% of that needed for a conventional substation.

Gas insulated substations offer other advantages in addition to the reduced space requirements. Because the substation is enclosed in a building, a GIS is less sensitive to pollution, as well as salt, sand or large amounts of snow. Although the initial cost of building a GIS is higher than building an air insulated substation, the operation and maintenance costs of a GIS are less. The primary applications for gas insulated substations include:

High voltage installations

The higher the voltage, the more favorable gas insulated technology becomes. The footprint of 765kV conventional substation is enormous, and GIS technology allows a significant size reduction.

Urban Installations

GIS technology can be used for installations in areas where the cost of real estate or aesthetic appeal is a significant consideration. Indoor Installations Building an air insulated substation indoors is usually impractical, but a GIS can easily go inside buildings.

Environmentally Sensitive Installations

GIS technology is popular in desert and arctic areas because it can be enclosed in a building with environmental control. Gas insulated substations also contain the electrical components within a Faraday cage and are therefore totally shielded from lightning.

Beta has completed several noteworthy GIS projects in recent years. The Glendale substation was unique in both its architectural design and engineering challenges – incorporating an aesthetically pleasing substation into the Los Angeles area. Beta was also involved in the design and construction of a GIS substation in Anaheim, California that is completely hidden by a park.