系统中发生单相故障时，零序回路中不包括(    )。

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69507' and id < 4502788 and id<>'4502788' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69507' and id > 4502788 and id<>'4502788' order by id asc limit 5