3-MV compact very fast transient overvoltage generator for testing ultra-high-voltage gas-insulated switchgear

Gas-insulated switchgear (GIS) is widely used today in electrical power systems because of its reliability, compaction, long maintenance cycle, and small impact on the environment [1]. In its use the normal operation of the disconnector generates very fast transient overvoltages (VFTO) with frequencies ranging from 1 to 100 MHz [2] and amplitudes up to 2.5 p.u. [3]. For systems above 330 kV, the insulation strength of the GIS under VFTO is of concern as insulation failures caused by VFTO have exceeded those caused by lightning impulse (LI) [4]. This characteristic has attracted the attention of researchers worldwide and currently is a hot topic in the field of ultra-high-voltage (UHV) GIS insulation.