投退直流小保险引起开关误跳原因简析

揭阳１１０ＫＶ榕城变电站１０ＫＶ粮食线二次回路曾发生投退直流控制电源小保险时，引起相邻线路开关误跳闸的事故。通过分析讨论，得出按周减载回路缺少负极小母线和直流系统存在接地点是造成这种事故的主要原因。最后，提出了从根本上杜绝事故发生的建议，即以微机线路保护装置取代小母线式旧装置。

Analysis of miss-trip of switches caused by switching of DC mini fuses

Switching of mini fuses in secondary circuit may occasionally cause miss-trip of switches of multiple adjacent lines. It is concluded through analysis that this kind of failure mainly results from the absence of negative small busbar in frequency-based load-shedding circuit and the defects in DC system. The author puts forward some anti-fault measures including adding diodes to frequency-based load-shedding circuit, enhancing the maintenance and management of DC system, and setting the switching sequence of mini fusec. It is also pointed out that using microcomputer-based line protective devices is a way to the thorough end of such failures.