The sand fell into the tank of a 500 kV circuit breaker during the installation process in Inner Mongolia Power Grid, In next year, after charging for 40 seconds, shield cover close to the moving contact discharged to the shell on this circuit breaker. The circuit breaker then returned to manufactory for future inspection. After repair, the circuit breaker brokedown again in the process of AC withstand voltage test. The abrasion inside high pressure gas reservoir during operation by grains of sand caused the fust failure, hi the maintenance process after the first failure, AC withstand voltage destroyed the insulated support barrel surface which resulted in breakdown of hand-over test. The failure analysis on the device shows the importance to conform to the relevant national applicable standards of HV electrical apparatus during construction.%蒙西电网一台500kV罐式断路器由于安装时罐体内部进入黄沙,次年春检结束恢复送电40s后,内部动触头侧屏蔽罩对壳体放电,断路器返厂修复.在修复后的现场交流耐压交接试验过程中,发生静触头侧支撑绝缘桶对地闪络故障,断路器二次返厂修复.通过对故障过程的分析,认为由于罐体内部存在沙粒,断路器在分合闸过程中压气缸内侧磨损,产生金属粉末,是首次故障的起因.首次返厂检修过程中,厂内740kV 工频交流耐压试验造成支撑绝缘桶沿面损伤,导致现场耐压击穿.针对这起故障,提出SF6高压罐式断路器在安装过程中需要严格执行施工规范的建议.
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