Impact of antioxidants on DC and AC electrical properties of XLPE-based insulation systems

In this article, the impact of two different antioxidants (Irganox® 1076 and PS802) on the electrical properties of a cross-linked polyethylene (XLPE) matrix is investigated and discussed. Materials were tested by means of dielectric spectroscopy, thermally stimulated depolarization currents (TSDC) and DC conductivity measurements to provide a comprehensive analysis for their applications under AC and DC electric fields. Results reveal that electrical properties are notably modified by the introduction of additives and the amplitude of variation is somehow proportional to the concentration of the additive with respect to the polymer matrix. In particular, TSDC measurements claim that antioxidants introduce deep traps (> 1 eV) inside the base material and the density of these traps increases in accordance with antioxidant concentration. Moreover, due to the polar properties of these species, the complex permittivity raises with respect to base XLPE, and it adequately follows the antioxidant concentration. On the contrary, negligible variations in terms of DC conductivity are recorded.