Evaluation of epoxy resin formulations for SF6 cable spacer materials

Research is underway at IREQ on the insulation performance of compressed SF₆ insulated cables for power transmission at system voltages up to 800 kV. The work reported here is concerned with the choice of materials for the design and testing of model size and full size spacers for 138 kV and 800 kV system voltage respectively. Five epoxy resin formulations were considered together with the effect of the filler. The electrical evaluation of the materials included the study of surface properties such as dry are resistance and tracking and erosion resistance and volume properties such as dielectric losses, permittivity and dielectric strength with point to plane geometry. The mechanical impact resistance was measured. Thermal measurements consisted in the evaluation of the heat distorsion temperature and the coefficient of thermal expansion. The test results and the usefulness of the tests with respect to the judicious choice of spacer dielectric materials are discussed.