一起线路及断路器故障的保护动作及断路器失断原因分析

某220kV线路故障，双端线路保护都正确动作，经断路器跳闸先切故障。但因外部过电压在断路器断口外部形成的电孤将过电压系统与断路器孤道接地，此时凭母线保护的断路器失灵保护启动将失灵断路器及相连点断路器跳开。详细分析了这次故障原因，提出在母线失灵保护动作使失灵断路器与该系统开断的同时闭锁对侧重合闸，以及增设绝缘防导功能的改进措施。

Protection of a fault on line and circuit breaker and its reasons

During a fault occurred in a 220 kV line,the line protections at two terminals acted correctly and the breaker tripped the fault,while the external over - voltage caused an arc,which grounded the over -voltage system and the breaker. Then the breaker failure protection of the bus pro - tection tripped out the faulty breaker and its connected breaker. The fault is analyzed in detail and the countermeasures are suggested:block the opposite recloser when trip out the faulty breaker,and enhance the insulation capability.