水位(wei)開(kai)關，具有低液(ye)位(wei)報(bao)警功能，   當液(ye)位(wei)低于預設位(wei)置(zhi)時(shi)(shi)，  延(yan) 時(shi)(shi)10s后(hou)發出(chu)報(bao)警開(kai)關量信號提供給外(wai)置(zhi)設備；延(yan)時(shi)(shi)報(bao)警是為了防止 液(ye)面晃動(dong)而(er)導致誤(wu)報(bao)警，報(bao)警持(chi)續時(shi)(shi)間0~25s(出(chu)廠設置(zhi))。