Study on on-line jacket insulation monitoring for 500 kV submarine oil-filled cable

Taking insulation condition of the submarine oil-filled cable which used in Hainan Interconnection Project as the research object,a synchronous detection technique by using four current sensors to monitor cable sheath insulation was put forward. The principle of the method was introduced and the ratio of jacket insulation leakage current and the inductance coefficient of grounding circuit current were proposed which can be used to judge the jacket insulation condition. The on-line monitoring system basic on the method was introduced,including the system composition and introduced the structure of current sensor in detail. Simulaiton software was used to build the cable model and simulation calculation on induced current and capacitive current were conducted. The simulation and monitoring results show that the monitoring system which can reflect condition of the cable insulation. The system was successfully put into operation in Hainan Interconnection project at present. The operation condition is good and test data is reliable,and provides an important basis on monitoring jacket insulation for submarine oil-filled cable.