Investigation on the electrical characterization of silicone rubber using DC conductivity measurement

Extruded cable systems and accessories are key components within the area of power transmission systems. Taking into account that the number of high voltage direct current (HVDC) transmission solutions is continuously increasing the role of its components and insulating materials becomes more and more important. In addition to transient and alternating current (AC) field stress the more important material characteristic for designing electrical equipment under DC stress is DC conductivity. For this reason, the purpose of this paper is to investigate the material characteristics of silicone-based insulation materials used in cable accessories in terms of temperature- and field-dependent conductivity. Although silicone rubber is a common application in cable accessories the knowledge about dc conductivity can be increased. Thin layers of LSR as representatives for insulation materials of cable joints are prepared. The variation of field strengths and temperatures are kept with regard to operating conditions. The electrical characterization is done based on ASTM D257-14 using guard ring electrodes. A variation of electrical contacting is carried out in compliance with this standard.