Study on Electrical Properties of Silicone Rubber Insulation for Cable Accessories Under Mechanical Stretching

Abstract

Silicone rubber (SR) is extensively used as insulation for cable accessories, directly affecting their design and operation. The distinctive feature of cable accessory insulation, operating under mechanical stretching, has not received sufficient attention in relevant standards and research. This study investigates two essential electrical parameters of SR insulation: relative permittivity and AC breakdown strength, analysing and summarising their variations during mechanical stretching. By comparing the parameter variations of SR samples with different filler contents and matrix compositions, the microscopic stretching behaviour and performance change mechanisms under mechanical stretching are explored. The results reveal the tensile effect on SR insulation, demonstrating that as the stretching ratio increases, the relative permittivity decreases, whereas the AC breakdown strength shows an increasing trend. Increasing filler content and incorporating low molecular weight components suppress the tensile effect, whereas decreasing filler content has the opposite effect. Given the significant correlation between these two parameters, the orientation and elongation of molecular chains are considered the primary factors influencing the tensile effect on SR insulation. This insight proposes a novel approach to control and optimise the performance of cable accessory insulation.