GSN3-12 is a new generation of green and environment-protective, AC metal-enclosed gas insulated switchgear (C-GIS), latest developed by Cooper power system. GSN3-12 is completely suitable for public and industrial distribution networks, infrastructure engineering, rail transit, metallurgy, petrochemical, docks, ships, drilling platforms and other fields, playing the roles of receiving and distributing electric energy, and controlling, protecting and monitoring circuits.