Box type fixed AC metal enclosed switch equipment, is a kind of intelligent, environmental protection, full working condition equipment, with high reliable operation safety, It is one of the most commonly used devices in urban ring networks. Use in electrical power system with three-phase frequency 50/60 Hz, rated voltage of 12kV. It is used for receiving and distributing electric energy in ring and segmented power supply systems. With full insulation, long life, maintenance free, small space, safe and reliable, not affected by the environment and other characteristics.