Electrical Fault Simulation and Gas Production Law of Dodecylbenzene Insulating Oil Based on Dissolved Gas Analysis

Dodecylbenzene insulating oil is a liquid dielectric material widely used in self-contained high-voltage cables and accessories with low viscosity, low dielectric loss, good gas evolution in electric field and high breakdown field strength, but has less research and application in China. In this paper, dodecylbenzene insulating oil produced by an enterprise in Nanjing is taken as the research object, and its physical, chemical and electrical properties were tested. The gas production law of 7 characteristic gases (H2, CO, CO2, CH4, etc.) in dodecylbenzene insulating oil during breakdown and oil paper surface flashover under AC voltage was mainly studied. IEC three ratio method and the Duval Triangle were used as the fault criteria and compared with the actual fault types to verify their applicability to dodecylbenzene insulating oil. The results show that dodecylbenzene insulating oil has good physical, chemical and dielectric properties; in addition to CO2, the concentrations of H2 and C2H2 increase significantly in the power frequency breakdown test, and H2, C2H2 and CO in the power frequency surface flashover test. The determination results using the IEC three ratio method are all low-energy discharges, and the Duval triangle method are all high-energy discharges. From the experimental results, it can be obtained that the IEC three ratio method is more accurate and practical for the electrical fault simulation experiment set in this paper.