Gas Insulated Station (GIS) which usually uses SF6 gas is usually used if the space allocated for the switchyard and/or substation is constrained or limited, like in urban areas or mountain cliffs. Since each component of the GIS like the breakers and bus bars are insulated, this type of substation is also used if the environment surrounding the switchgear is corrosive or not favorable for the equipments; such places are geothermal fields and near coast lines.
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