AC or DC Corona Ageing of HTV Silicone Rubber

The test rig proposed by CIGRE WG D 1.14 [1] for evaluating the resistance to corona and ozone of polymeric materials for high voltage outdoor applications makes use of a multi-needle electrode as an artificial corona source for treatment of material samples. The electrode can be energized from either AC or DC high voltage sources. Two types of commercially available high temperature vulcanized silicone rubbers (HTV) were selected for the study described in this paper. Experimental investigations were carried out to evaluate dielectric properties (e.g. surface and bulk resistivities, dielectric response), mechanical properties (e.g. tensile strength, elongation at break), and chemical structural changes (analyzed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR)) of material samples after exposure to ac or dc corona discharges. In addition, the loss and recovery of hydrophobicity of the materials were characterized by contact angle measurements