Switching phenomena in medium voltage systems - good engineering practice on the application of vacuum circuit-breakers and contactors

This paper summarises the transient phenomena and overvoltages when switching with vacuum circuit-breakers and vacuum contactors in medium voltage systems (1 kV <; U ≤ 52 kV). It describes the interaction between switching devices and network as well as the most influencing factors for the shape and magnitude of overvoltages. Based on studies, laboratory and field tests, engineering and mitigation guidelines are presented intended to cope with transient overvoltage phenomena. It is the aim of this paper to demonstrate that adequate surge protection ensures safe and reliable system operation with vacuum switching devices.