一起500kV SF_6断路器爆炸事故分析

Analysis of an Explosion Accident of 500 kV SF_6 Circuit Breaker

针对兴仁换流站发生的一起500kV SF6断路器爆炸事故,根据SF6断路器的灭弧室结构、开断原理及动作过程,结合现场实际情况,分析了事故的各种可能因素。确定了该起事故的原因为T型机构箱内转轴的轴承漏装,多次分合后转轴逐渐移位,并磨损了传动机构的1个销子,最终导致销子脱落;断路器合闸后弧触头不能接触,出现稳定短电弧导致灭弧室内气体发热,压力升高,灭弧室发生爆炸导致电网短路事故。对制造厂的质量控制提出了建议,以避免类似事故发生。

This paper introduced an explosion accident of 500 kV SF6 circuit breaker in Xingren converter station, the structure of breaking unit,theory of interruption and action process about the SF6 circuit breaker was discussed, combining with the practical situation, all possible factors of the accident is analysised.Finally the reasons of the accident were presented：the shafts in the T-mechanism were displaced caused by the two missing bearings after many opening and closing,a pin had sheared off by the excessive forces and finally breaked off from the mechanism; the arcing contacts could not contact after closing operation, a stable short arc was initiated across the arcing contacts,the pressure inside the breaking unit increased for the heated gas.At last,the interrupter exploded and led to a grid short circuit accident. To avoid similar accidents,this paper provided the corresponding proposal about quality control of manufacturers.