US Patent 9343881 Gas-insulated switchgear

A gas-insulated switchgear assembly is provided that includes a housing having an interior containing insulating gas. A disconnector is disposed in the housing and includes a movable contact, as well as fixed contacts that are spaced apart and arranged linearly in a direction perpendicular to a wall of the housing. The movable contact has a colored or topographical marking and is linearly movable among a plurality of positions. The wall of the housing is provided with an inspection window that permits a person to see the colored or topographical marking in relation to the fixed contacts, thereby permitting the person to determine the position of the movable contact.