Comparative investigations on offline Pd-measuring with UHF and standard PD-measuring equipment applying 50Hz AC and damped AC on 110-kV-XLPE-cable

In the area of high voltage cables assessment, PD (Partial Discharge)-measurement on-site is becoming more and more important. Not only for testing cables on-site along with the commissioning tests, but also to monitor the condition of the cable after long time of service. Here, it is of special interest to detect the potential failures or degradations inside the cable accessories in order to prevent the breakdown during service. Online condition monitoring was developed over the past with good results, showing the measurable PD under service voltage. Likewise offline PD measurement is also applied during on-site commissioning tests with resonant test voltage (20 Hz-300 Hz) with good experience. This paper shows a comparison of UHF PD-measurement using 50 Hz AC and Damped AC (DAC) on an operating 110-kV-Cable circle in the lab. At the same time a standard PD-measurement (IEC 60270) will be applied to compare the UHF PD-data with them. The 110-kV-Cable circle consists of a 110-kV-cable with one slip-on joint and two terminations filled with silicone fluid.