Developments in ring main unit design for improved MV network performance

Ring main units have evolved from their original application as simple MV/LV transformer tee-off points into a much more vevsatile tool. The hey development has been the introduction of low-cost SF6 rotating are circuit breakers with integral earth and testing, as well as advances in communication and control technologies. Further improvements in network security and availability can be achieved by applying the RMU circuit breaher as a sectionalising point.