Frequency characteristics of electromagnetic wave radiated from GIS apertures

Partial discharge (PD) measurement using electromagnetic wave by antennas is a promising technique to diagnose the insulation performance of GIS. In order to establish highsensitive diagnosis technique of GIS insulation, frequency characteristics of electromagnetic wave, which are determined by GIS apertures such as insulating spacers and bushings, should be clarified. In this paper, we measured the electromagnetic wave radiated from different GIS apertures and also analyzed it using transient analysis program “PSpice.” Comparing the measurements with the theoretical analyzes, we investigated the relationship between the GIS aperture configuration and the radiated electromagnetic wave spectrum from the aperture.We also discussed how the aperture condition contributed to the radiation characteristics of electromagnetic wave. Finally, we concluded that the electromagnetic wave radiated from GIS aperture was based on different radiation mechanism in frequency.