【精品】专业英语13章电气工程英语翻译.doc

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1、12.3GroundingofElectricalSystemsIngeneral,mostelectricalsystemsmustbegrounded・Thepurpose277/480VLoadcenterDistributiontransformer23OOV9200VLoadcencer277/480VTransformer277/480VTransformer2300V23OOVLoadcenterMaincircuitbreaker

2、120/208VLoad

3、Transformer

4、center120/208VI277/48OV2300V277/480VTra

5、nstonner^23dOV■"Maindisconnect2300VFeederpanelTransformer!20/208VLoadcenter2300V2300V1>ansforrner120/208VTransformer2300V277/48°VTransformer]Load120/480Vcenter2300V277/480VLoadLoadcentercenter277/480V277/480V277/480VFig.12.4Secondaryhigh-voltageradialdistributionsystemofgroundingistolimitt

6、hemagnitudeofvoltagecausedbylighting,momentarysurges,andaccidentalcontactwithhighervoltages・Systemgroundsmustbeseaweedtoprovideapathofminimumimpedanceinordertoensuretheoperationofover-currentdeviceswhenagroundfaultoccurs・Currentshouldnotflowthroughthegroundingconductorduringnormaloperation

7、.Direct-currentsystemsgenerallyhavethegroundingconductorconnectedtothesystematthesupplystation,andnotattheindividualservice.Alternating-currentsystems,ontheetherhand,mustbegroundedondiesupplysideofthemaindisconnectaleachindividualservice・Forspecificinformationanthelocationandmethyloffundin

8、g,refertoNECArticle250・IoadcenterLoadcenterLoadcenterLoadcenterladcenter[cb]IRb]

9、CBl

10、CB

11、i277/480-VLoop300VLineioistributionsfonrwrsfCBlLoadcenterCBTransformer「Tran尿rm石CB277/480-VLoopTransformerLeadcenterMaindisconn-厂—j-cctand彳Transfbrmerfeederpanel23OOVEmIrattstbnner[CBJ

12、cb

13、[CB

14、.1cb

15、LoadL

16、oadLoadl.oadcenlo-centercentercenterLoadcenter(a)Secondaryhigh-voltagedistributionsystem;high-voltageradical・1ow-voltageloopTodistributiontransformer(b)Consumerdistributionsystemwithhigh-voltageandlow-voltageloopsFig.12.512.3GroundingofElectricalEquipmentMetalconduitandcaseswhichencloseele

17、ctricalconductorsmustbegrounded.Iftheungrounded(hot)conductorcomesincontactwithametalenclosurewhichisnotgrounded,avoltagewillbepresentbetweentheenclosureandtheground.Thispresentsapotentialhazard・Personacomicincontactwiththeenclosureandgroundwillcompleteacircui