Analysis and performance of high voltage DC power supplies used for low current measurements on dielectric materials

Characterization of the conductive current associated with XLPE, found in power cables requires HVDC power supplies with very stable voltage output. The very low conductivity has led to an increased need of a more accurate measurement technique to characterize the conductive parts of dielectric materials. Commercial HVDC power supplies used for such measurements do not provide a pure DC due to the power electronics that contribute to a high frequency component which in return generates a capacitive current. The generated capacitive current can be difficult to differentiate with the actual measurement of the conductive current. In order to achieve measurements of the conductive current, the influence of the generated capacitive current must be sufficiently lower than the conductive current. By designing a power supply with low ripple generation, the influence of the capacitive current can be diminished. A ripple and harmonic free HVDC power supply consisting of 1 kV battery pack was therefore developed to examine the impact of the high frequency component of commercial HVDC power supplies.