Tenbohlen "New Procedures for Partial Discharge Localization

Abstract: This paper introduces to new methods providing a cost-efficient localization of partial discharges (PD) in gas-insulated switchgears (GIS). A new analogue signal-processing unit minimises necessary equipment for a time-of-flight measurement (time domain) by means of time-to-digital (TDC) converters. The analogue signal processing unit recognizes the beginning of the UHF-signal and acquires start and stop commands for the TDC. The TDC measures the time difference (㥀t), which is necessary to localize the PD. Another method uses the interference phenomenon of two superimposed sensor signals in the frequency domain. The signal interference is generated by the time delay (㥀t) between the signals. Two similar sensor signals are required to receive acceptable results for the measurement procedure. Considering the dispersion effects of higher modes in GIS only a certain frequency range is useful for the measurement. At various setups the interferences were measured. Both methods are able to evaluate the time delay between the sensor signals and to localize PD in GIS in a cost-effective way.