Peroxide Decomposition Products in Factory Joints for DC XLPE Submarine Cable

Flexible joints are necessary for submarine cable system to facilitate installation of long cable lengths. For extruded submarine cables, joints are typically manufactured using the same type of insulation materials as the cable to retain similar flexibility and mechanical properties as the cable. This commonly includes crosslinking the joint during manufacturing which generate peroxide decomposition products. Removal of methane from crosslinked joints through degassing is common practice for HVAC or EHVAC cables but for HVDC cables liquid decomposition products need to be removed as well. A detailed study of the distribution and development over time of methane and liquid decomposition products is presented here.