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.

I. Introduction

Underwater high-power connectors are widely recognized as one of the most critical components in offshore power delivery systems. Studies have reported that connection failures are responsible for many unsuccessful subsea and offshore proj ects, making the reliability of cable connectors a crucial factor in subsea applications [1], [2]. In contrast to traditional cable connectors, subsea connectors must be able to withstand the harsh and challenging conditions present in their underwater environment. These conditions include corrosive and conductive seawater, high pressures of up to 300 bar at depths of up to 3000 meters, and temperature variations [3]–[6]. Therefore, the electrical insulation of subsea connectors is a critical factor in their design and development. As such, careful consideration and understanding of the electrical properties of insulation materials are essential to ensure the long-term safe operation of subsea connectors.