电气专业毕业设计外文翻译防雷接地.docx

电气专业毕业设计外文翻译防雷接地.docx

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电气专业毕业设计外文翻译防雷接地

Lightningprotectiongrounding

AbstractThesignificanceoflightningp.rotectionandmitigationonverylittlemoneytopreventlargelosses,anditsfunctionistousescientificmeansavoidnaturaldisasters.Groundingistomakethesystemhasbeenincludedinthelightningprotectionlightningenergydischargeintotheearth,andgoodgroundingcaneffectivelyreducetheonlineguideovervoltage,avoidcounterattack.Avoidgroundisthemostimportantaspectoftechnology,whethersingsrem,inductionlightning,orotherformsofray,ultimatelythelightningcurrentintotheearth.Therefore,noreasonableandgoodgroundingdeviceiscan'treliablythelightningstrikes.Thesmallerthegroundingresistance,comelooseflowisquicker,lightningobjectsthetimetomaintainhighpotentialmoreshort,thelessrisk

KeyWords:

Lightningprotection;Grounding;Current;potential

1introduction

Inrecentyears,manydomesticandforeignstandardsdonotadvocateinformationequipmentusingindependentgroundingdevice,recommendtheuseofcommonearthingsystem.Forexample,the2000editionoftheGB50057-94"designcodeforprotectionofstructures"inpointoutclearly:

"everybuildingitselfshouldadoptcommonearthingsystem"tobethebuildingswithinthevariousgroundingareunifiedtobuildingsbasedon,oroutdoorgroundingdevice.Whenthebuildingwashitbylightning,powersystemvoltageandelectricalequipmentgroundingvoltagerisesatthesametime,keeptheequipmentworkingvoltageconstant,sothattheelectronicequipmentfromlightningstrikescanworknormally.Commonearthingsystemusuallyusethebuildingfoundationgroundingelectrode,thegroundingresistancelessthan1ohmingeneral,iftheequipmentgroundingresistancerequirementislower,shouldtaketheminimumvalue.

Thegroundthathasbeenincorporatedintothelightningprotectionsystemoflightningenergydrainintotheearth,goodgroundingdownleadtoeffectivelyreducethevoltageontheback,toavoidtheoccurrenceof.Inthepastsomerequirementsofelectronicequipmentgroundingalone,thepurposeistopreventstraycurrentandtransientcurrentinpowernetworkdisturbanceofthenormalworkofequipment.Before90time,forcesofthecommunicationnavigationequipmentelectronictubedevice,usinganalogcommunicationmode,analogcommunicationonparticularlysensitivetointerference,interference,sowilltakepowerandcommunicationsgroundingseparateway.Now,thelightningprotectionengineeringfieldsdonotadvocateaseparateground.IntheIECstandardsandITUstandardsarenotadvocatingaseparateground,AmericanStandardIEEEStd1100-1992moresharplypointedout:

notrecommendedtheuseofanykindofso-calledseparate,independent,computer,electronicorothersuchincorrectgroundasequipmentgroundingconductorofaconnectionpoint.Groundingisthemostfundamentalaspectofthelightningprotectionsystem.Thegroundisnotgood,allthemeasuresoflightningprotectioneffectcanplay.Lightningprotectiongroundingisgroundcommunicationstation

Codeforconstructionandacceptanceofthebasicsafetyrequirements,thegroundingofPLCbelongstoalow-voltageelectricalequipmentofsinglepointgroundingmode

Lowvoltageelectricalequipmentofsinglepointgroundingmodecanbedividedinto:

tandemtypesinglepointgrounding,paralleltypesinglepointgrounding,multiplebranchingofsinglepointgrounding.

2singlepointgroundingmethod

Tandemtypesinglepointgrounding:

orfirstgroundingways.Method:

thenumberoflowvoltageelectricalequipmentgroundingterminalequipmentwiththesamerootnearthegroundwireconnecting,thenthroughthisgroundingandgroundingdevice.Thegroundingsystemis:

savemanpower,materialresources;whilethedisadvantageisthat:

whenthepublicgroundinglineopencircuit,ifthegroundingsystemhasadeviceleakage,cancauseotherequipmentwhichoccurredonvoltage,athreattothesafetyofpersonnel.

Backupgroundterminalintroducingagroundingline,andthenthenumberoflinesatthesametimereceivedagroundingdevice.Thegroundingsystemis:

whenthegroundingsysteminwhichadevicegroundingwirebrokencircuit,willnotcauseotherequipmentenclosurevoltage,toensurepersonalsafety.Thisgroundingmodeis:

ifitisnotperfectontheinterferenceofhighfrequencyelectronicequipmentorotherhighlysensitiveelectricalequipment,highfrequencyinterferencefromotherdevices（suchasconverter,intermediatefrequencystovethyristorconverterparts）willbefromthecommonplaceofstring,causingthedeviceisnotworkingproperly.

Multiplebranchingofsinglepointgrounding:

orthirdgroundingways.Groundingmethod:

eachequipmentgroundingterminalalonereceivedagroundingdevice.Earthingmethodandsecondkindsofgroundingisthedifference:

thedevicehasasep