It is equipped with three-position switch which is gas insulated and maintenance-free.@#Phases are arranged from forward to backward without inter-phase cross insulation.@#It is equipped with bus system on top and air insulation is adopted for connection between bus and cable.@#It is in cell-typed or metal-clad cabinet design.@#Pressure release: backward and top-oriented. Release by each cell.@#Optional: top low-voltage room and cabinet heating equipment (applicable to poor environment conditions, for instance: condensation).@#Optional: complete control, measurement and protection system.@#