时间继电器在继电保护中主要实现（  ）。

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69477' and id < 4500135 and id<>'4500135' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69477' and id > 4500135 and id<>'4500135' order by id asc limit 5