In practice, some differential bus protection had miss operation because of its unpractical criterion. It is analyzed and presented in this paper based on this situation.

• 文章对旁路开关微机保护转代线路开关时的一次动作行为进行了分析，指出了动作原因，提出了防范措施，在实际工作中有一定的借鉴意义。