A study on variation of properties of silicone rubber by swelling

In order to build underground the transmission line, it is necessary to install outdoor terminations that connect overhead transmission lines and underground power cables. The inside of the outdoor termination is filled with insulating oil and a stress relief cone made of silicone rubber is assembled at the end of outer semiconducting layer. Insulating oil is heated to lower viscosity prior to injection, which requires additional equipments and more time. It is necessary to examine the influence of impregnated silicone rubber on the use of low-viscosity insulating oil that can be injected without heating. In this paper, we investigated how much silicone rubber swells depending on the viscosity of three different insulating oils. The mechanical and electrical properties such as tensile strength, elongation, volume resistivity, relative permittivity, etc., of the fully swollen silicone rubber were measured. In addition, the chemical analyzes of the fully swollen silicone rubber through FTIR and TGA were performed. Copyright © The Korean Institute of Electrical Engineers