Thermal aging property and breakdown property of submarine cable materials

As an important high voltage transmission equipment, XLPE cable plays an important role in submarine transmission engineering. In the long run, the performance of cable material is directly related to the overall insulation performance of the cable. In the work, the aging property and breakdown property of submarine cable insulation material and semi-conductive material are studied. Firstly, the semi- conductive layer, insulation layer, and composite structure specimen of the semi-conductive and insulation (S-I) layer were prepared by the plate vulcanizing press. Secondly, specimens were treated in a vacuum aging chamber at 135°C for 600 h. The morphology and groups of the samples before and after thermal aging were studied by SEM and FTIR. Finally, the breakdown strength of the insulation sample and composite sample before and after thermal aging were measured. The experimental results show the chemical bonds and functional groups in insulation samples after aging has little change. By contrast, the C-O bond in the methyl and ester carbonyl group decrease after semi- conductive layer aging. The breakdown strength of insulation samples after thermal aging decreases by 23.66%. The breakdown strength of the composite sample after thermal aging decreases by 26.50%.