SF6 ring main unit is a medium voltage electrical combination equipment with load switch as the core component, which can be freely combined into multiple circuits with switching, connection, and protection functions for the power system. Its main circuit core components are composed of SF6 load switches or additional circuit breakers and other primary auxiliary electrical appliances.
SF6 ring main unit can be divided into expandable and non expandable types according to their combination, such as Safering and Safeplus (ABB). According to different production and manufacturing processes, it can be divided into common box type (also known as gas filled cabinet or SF6 fully insulated cabinet) and modular type, such as RM6 and SM6 (Schneider).
In recent years, the development of SF6 ring main unit has been very rapid, and both the manufacturing process and product reliability are on par with international electrical giants. However, there is still a certain gap compared to foreign manufacturers in voltage levels between 24kV and 40.5. At present, there are only a few domestic manufacturers producing SF6 distribution grade at 40.5kV level. The rest are C-GIS systems based on high current and large capacity primary power systems.