对±500 kV江陵和龙泉换流站直流分压器的外绝缘闪络事故进行了分析，指出该分压器发生闪络事故的原因：一是复合套管的憎水性完全丧失；二是复合套管的均压环结构不合理；三是复合套管的伞裙形状参数特性较差。发生闪络事故的主要原因是复合套管的憎水性完全丧失，其次是均压环结构不合理。在此基础上，针对分压器的结构和事故性质，提出从根本上解决问题的思路：应按所要求的电气、机械和憎水性能来选用复合套管外绝缘材料；按上下均压环中心距离和均压环直径能保证复合套管的爬电距离和干弧距离的有效性与设计值接近这一主要原则来重新设计均压环；建议复合套管的伞伸出大于或等于70 mm，伞间距至少为70 mm来重新设计伞形。同时，建议可以采取在复合套管的外绝缘表面上涂覆防污闪涂料PRTV（permanent room temperature vulcanizedanti-contamination flashover composite coating）来提高外绝缘强度处理措施。

Abstract: The Gangneung and ± 500kV DC divider Longquan Converter Station external insulation flashover is analyzed. That the occurrence of flashover voltage divider reasons: First, hydrophobic composite casing completely lost; Second, the composite casing sheds less characteristic shape parameters; Third, the mean composite casing grading ring structure is irrational. Flashover occurs mainly due to hydrophobic composite casing completely lost, followed by grading ring structure is irrational. On this basis, for the voltage divider of the structure and nature of the incident,Propose a fundamental solution to the problem of thought is required by this article shall be electrical, mechanical and hydrophobic properties in the selection of composite insulation material casing; by down grading ring center distance and diameter of both grading ring composite casing ensures creepage distance and the effectiveness of dry-arc distance and the design value close to the main principles to re-design of grading ring ; the proposed umbrella out of composite casing greater than or equal 70mm, 70mm at least to re-pitch the umbrella design umbrella. Also suggests that the casing can be taken outside the insulation in the composite surface coating to enhance RTV-Ⅱ antifouling coating to increase the flash intensity of treatment measures of external insulation.