Very fast transients in 1000 kV HSGS grounding circuit

Very fast transients (VFTs) in a grounding circuit of a 1000 kV class high speed grounding switch (HSGS) were investigated. Referring to the VFT voltage levels estimated by the investigation, the structure of their grounding circuit was designed. The suitability of the design was confirmed by a low voltage test and a high voltage test, which were carried out using the HSGS for a field test.