Application of surge diverters to the protection of gas insulated substations

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Gas insulated substations (GIS) are exposed to the same types of overvoltages as conventional substations i.e., lightning overvoltages, switching overvoltages and temporaryovervoltages. Possible means to limit over voltages in GIS are active gap surge diverters and metal oxide surge diverters. The objective of this project is to study the effects of the system configuration on the performance of these two types of overvoltage limiting devices. This dissertation could be considered as consisting of four main parts. Chapters two and three give a description of gas insulated systems and of surge diverters respectively. Chapter four underlines the principles of insulation coordination involved, and does perhaps suggest how the problem should be approached. Chapter five gives a fairly comprehensive review of the principal methods of calculation and describes the computer program used. Finally, the results are presented and discussed in chapter six, and some general \ conclusions are suggested in chapter seven.Various articles and publications are referred to throughout the dissertation, giving an insight into the history of the subject, as well as providing further useful sources of information to the reader.