Medium voltage (MV) SF6-insulated ring main unit for secondary distribution up to 40.5 kV, 630A. SafeRing is a ring main unit (RMU) for the secondary distribution network. It is available in 18 different configurations suitable for most switching applications within the range from 6 to 40.5 kV. The standardized RMU configurations, which are mostly required within a distribution network, can be extensible upon request. Safe Ring is a completely sealed system with a stainless steel tank containing all live parts and switching functions. A sealed steel tank with constant atmospheric conditions ensures a high level of reliability as well as personnel safety and a virtually maintenance-free system.