Experimental Investigation of the Surface Current on Polluted HVDC Polymer Insulators

In this work, two configurations of polluted silicone insulators were investigated experimentally for the resulting surface currents when loaded with a positive DC voltage up to 30 kV. The two pollution layers, one drop-like, one continuous, turned out to be visibly different concerning their conductivity, as well as their susceptibility to partial discharges (PD) on the surface when exposed to rising humidity. Furthermore, the importance of long-term studies to observe DC currents without polarization or alternating components was confirmed, in agreement with previous research in this field. Despite the different characteristics of the impurity layers, the selection of different impurity layers emerged as a robust assessment of the insulators’ performance, and as a basis for mathematical modeling of further progression of the surface current over time.