Characteristics of planar capacitor sensors with dielectric window for very fast transient overvoltage measurement in gas insulated switchgears

Planar capacitor sensors have been widely used for measuring of very fast transients overvoltage (VFTO). A dielectric window made of epoxy was proposed to reduce the time required for installation of the sensor. The thickness of the dielectric window was calculated to provide a SF
₆
pressure durability, and the frequency response of the dielectric window was investigated by pulse response experiment. Waveform measurement of switchgear operation demonstrated that the planar capacitor sensor with the dielectric window has a good bandwidth to make accurate measurement of VFTO.