Measurement of very fast transient overvoltages (VFTO) in a GIS module

Gas insulated substations (GIS) have found a wide range of acceptance in power system for their compactness, high reliability and freedom from periodic maintenance (large mean time between failures). This paper deals with the design and development of a capacitive voltage divider for measuring VFTO, as encountered in GIS. The short response time for the divider is achieved by forming the high voltage arm of the divider in the gas insulated bus-duct itself. Further, the simulation of VFTO has been carried out using Electromagnetic Transient Program (EMTP). The comparison of measured and the simulated VFTO validates, satisfactorily, the performance of the new divider