Analysis and experimental study for current break systems in a load break switch of RMU

Ring Main Unit(RMU) with a load break switch is designed to meet the growing requirements for oil — free, maintenance free, long life, maximum safety and future feeder automation application. SF6 gases as insulating and arc-quenching medium ensure the positive breaking of small current, main active load current, cable charging current, magnetizing current etc. The closing and opening motion of the switch is completed by a rotating shaft within several tens of milliseconds. Therefore, it is very difficult for product developer to observe the arc phenomena caused by the magnetic forces between two contacts. In this paper, to determine the characteristics of magnetic forces applied in the system of load break switch, electromagnetic analysis is performed on the load break switch contained permanent magnet. Experimental verification of arc phenomena using high speed camera is carried out as well.