Ground switches in GIS
Ground switches feature a moving contact that creates or closes a gap between the high - voltage conductor and the enclosure. At the enclosure and the conductor, sliding contacts equipped with suitable electric - field shields are incorporated.
A “maintenance” ground switch can be operated either manually or via a motor drive. It takes several seconds to open or close, and when fully closed, it can carry the rated short - circuit current for the specified time period (either 1 or 3 seconds) without sustaining damage.
A fast ground switch is equipped with a high - speed drive, typically a spring, and contact materials designed to endure arcing. This enables it to close onto an energized conductor twice without causing significant damage to itself or nearby components. Fast - acting ground switches are commonly utilized at the connection point between a Gas - Insulated Switchgear (GIS) and the remainder of the electric power network. This is not only to address situations where the connected line is energized but also because these switches are more adept at handling the discharge of trapped charge and interrupting capacitive or inductive coupled currents on the connected line.
Ground switches nearly always come with an insulating mount or an insulating bushing for the ground connection.The picture depicts a GIS ground switch.
