Influence of Test Voltage Source on Extruded Cables for PD Testing – DAC vs 50/60 Hz

Inhalt:
A direct comparison of PD behaviour and PD assessment outcomes between Damped AC (DAC) and 60 Hz test voltage is conducted on a variety of MV cable defect types. Key parameters compared across the two test source types include PDIV, PDEV, discharge magnitude (pC), PRPDs and PD event counts / repetition rates. The paper aims to provide end-users with an independent understanding of what impact (if any) may occur on the same type of defect when utilizing a DAC based versus 50/60 Hz based PD measurement system. The study clearly illustrates the defect specificity / de-pendency of results obtained, which contrasts with other studies which have often drawn broad conclusions regarding source effects from a relatively small range of defect types. The implications of the work extend directly to PD testing of MV cables in commissioning contexts. However, indirectly, the results are likely applicable to higher voltage class cables as key behavioural dependencies observed are expected to be present at higher voltage stresses relative to those considered in this study. The study also provides an OEM independent, broad range of results which can support discussions within ongoing standards development efforts, and hopefully translates into end-user guidance to increase the accuracy and repeatability of field PD measurements, particularly when executed with DAC sources.