Comparison of Partial Discharge Behavior with Alternating Current and Damped Alternating Current at Different Frequencies

This article presents investigations of partial discharges (PD) in a high voltage cable system using different voltage shapes and frequencies. The two voltage sources which were used for energizing the cable system, are 50 Hz alternating current (AC) generated by a high voltage transformer and damped alternating current (DAC). Both systems can be used for PD detection with use of a standard PD measurement circuit consisting of coupling capacitor and coupling device with digital signal processing. With the help of an artificial PD source, the PD level is compared for AC and DAC and also the phase relation of PD for both methods is shown. Moreover comparison of partial discharge inception voltage (PDIV) for both energizing methods is described and measurements are shown. The measurements with the DAC source were performed at three different frequencies. Changing the resonant frequency is handled by adding capacitors in parallel to the cable system to increase the overall capacitance. Keywords—partial discharge, high voltage cable, PD detection, damped AC, artificial PD, PD measurement