Since the 50s of the 20th century, the development of medium-voltage switchgear has gone through the stages of open type, box type, metal enclosed type, etc., and there is no problem in meeting the functional use requirements of the equipment, and the product has long been serialized and the scope of use is fully covered. The rapid development of small size, maintenance-free, high modularity, safe and reliable environmentally friendly gas-insulated ring main unit can realize remote monitoring, control and management of the power system distribution network, and realize the needs of power grid optimization, electricity safety, power management, energy saving and consumption reduction; At the same time, the system can be widely used in transportation, factories, hospitals, schools, buildings, residential areas and commercial office buildings and other intelligent power distribution fields.