Very Fast Transient Overvoltages (VFTO) in Gas-Insulated UHV Substations

Recent developments in UHV substations renewed the importance of the very fast transient overvoltage (VFTO) analyses, which became a design factor for such UHV levels. VFTO are of greater concern at the highest rated voltages. Beside a detailed description of the state-of-the-art of science and technology the TB presents an insulation co-ordination approach dealing with VFTO. Technical information is given about VFTO simulation, determination of required withstand voltages, mitigation measures and special test requirements.