高频闭锁方向保护有两个电流启动元件，灵敏度高的元件的作用是（   ）。

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69378' and id < 4491447 and id<>'4491447' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69378' and id > 4491447 and id<>'4491447' order by id asc limit 5