Analysis of the sensitivity of the UHF PD measuring technique

Over the last years the UHF PD measuring technique has proven to be a very sensitive measuring tool for gas insulated systems. However, the sensitivity of the method strongly depends on the type of discharge and the number and type of GIS components between the discharge and the sensor. In this paper investigations regarding UHF signal propagation through GIS are analysed, in particular UHF signals originating from real discharges and artificial pulses. Based on measurements in a laboratory set-up it is shown that it is not possible to determine one value for the signal reduction of different GIS components. Moreover, a linear dependence of the signal reduction of a GIS component on the magnitude of the UHF signal propagating through this component has been observed.