Effect of Temperature on Breakdown Voltage of Silicone Rubber Insulation Used in Subsea Cable Connectors

Subsea cable connectors are essential components in offshore power delivery systems, commonly using a solid-liquid composite insulation system. However, there is limited literature on the electrical characterisation of such systems when the conventional mineral oil is replaced with an environmentally friendly ester liquid. This paper investigates the breakdown strength of SiR immersed in a synthetic ester liquid under different temperatures. The specimens were heated up to
$80^{\circ}\mathrm{C}$
using an open loop circulation system and placed between cylindrical electrodes to induce breakdown. The results showed that the breakdown voltage and hence breakdown strength slightly decrease with increasing temperature. Additionally, the location of each breakdown event was recorded showing that 95% of the events occur in the proximity of the triple point.