Study and Analysis on Biodegradation Performance of Alkyl Benzene Insulating Oil Used in Oil-Filled Submarine Cable

Oil-filled submarine cable is widely used due to the mature technology, excellent electrical performance, and the ability to continuously drain oil after failure, which can prevent the rapid expansion of faults caused by seawater infiltration. While, following a failure of this kind of cable, it is essential to investigate the biodegradation of alkylbenzene insulating oil after leakage and assess if it aligns with the degradation rate specified by cable suppliers. Research findings indicate that the degradation of submarine cable insulating oil in natural seawater reaches 13.2% in 7 days and 44.0% in 28 days. In the presence of activated sludge bacteria, the biodegradation rate is 50.9% in 7 days and 75.9% in 28 days, deviating slightly from the expected degradation rate, possibly due to the specific marine environment. It is crucial to evaluate the seawater degradation efficiency of the project post-oil leakage, so as to conduct environmental assessments based on the leakage situation and formulate targeted measures for recovering insulating oil, active bacteria that have no impact on the environment can be added when necessary to increase the degradation rate. Additionally, the study reveals that alkylbenzene insulating oil with fewer alkyl branched chain carbon atoms on the benzene ring degrades faster under similar conditions. Therefore, when selecting alkylbenzene insulating oil, it is recommended to choose the to choose the one with less branched alkylbenzene.