Improved EHV line switching surge control by application of MO-arresters and controlled switching

Transmission line switching surges and its limitation by means of metal-oxide (MO) surge arresters and controlled switching are discussed. The benefits of these overvoltage control methods are analysed based on extensive simulation studies of 550 kV transmission lines. The line length is taken as an independent parameter and the degree of shunt-compensation is considered as well. The simulation studies show that MO arresters and controlled switching cope in most cases with the insulation coordination requirements of 550 kV networks, thus eliminating the need of closing resistors.