Transient Lightning Overvoltage Protection Requirements for a 500 KV Gas-Insulated Substation

This paper summarizes the results of an insulation coordination study of 500 kV gas-insulated substations. The study is more comprehensive than others reported to date in that the overhead line connected to the substation is also considered and an attempt made to predict the amplitude and rise time of incoming overvoltages. A six- breaker arrangement was selected for the basic analysis and a wide variety of possible circuit configurations was studied. A 396 kV arrester was chosen as the basic protection device.