| The 500kV self-contained oil-filled cable of Hainan interconnection project is the first ultra-high voltage, large capacity, long distance submarine transmission line in China. It connects China Southern power Grid with Hainan Grid through Qiongzhou Strait. The insulation conditions determine whether it can operate safely. So it is important to do preventive test in order to find out the insulation status of submarine cable.Many research institutions all around the world have developed many test methods and items. Though, the attitude toward these methods has a lot of differences at home and abroad. So the test items and methods are still in research stage. According to the special environment, large insulation resistance and capacitance of submarine cable, the paper analyzes the ability to find insulation defects of various test methods, and realizes effectiveness of them. Meanwhile, concrete test methods are researched and equipments parameters are calculated carefully. On this basis, this paper considers test fields, conditions, and volume, weight, transportation, storage of test equipments, and draws conclusions about whether the test methods are feasible. In the end, the paper presented test scheme that is fit for submarine cable based on their effectiveness and feasibility.The study finds that AC and DC withstand voltage test, insulation resistance test, loss tangent test and partial discharge test have disadvantages that they need large capacity, high voltage and huge sized transformers, and they may cause damage to the insulation, or couldn't examine insulation clearly. As a result, they should not be implemented in the submarine cable. It is suggested that leakage current test and insulating oil test be carried through because of their effectiveness and feasibility. At the same time, online monitoring of cable sheath insulation and main insulation could be considered in order to supervise the cable insulation more comprehensively. |
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