水力发电厂高压电气设备选择及布置设计规范（NB-T 10345-2019）英文版

IIContents1 GeneralProvisions 12 Terms 23 BasicRequirements 33.1 GeneralRequirements 33.2 Electricalrequirements 33.3 Mechanicalrequirements 43.4 Climaticandenvironmentalrequirements 54 TheSelectionofHighvoltageElectricalEquipment 84.1 Conductor 84.2 MainTransformer 134.3 AuxiliaryPowerTransformer 164.4 GeneratorCircuit-breaker 174.5 Electricbrakeswitch 174.6 HighvoltageCircuitBreaker 184.7 HighvoltageLoad-breakingSwitch 184.8 HighvoltageDisconnectorsandEarthingSwitches 194.9 GasInsulatedMetal-enclosedSwitchgear 204.10 ACMetal-enclosedSwitchgear 234.11 Highvoltagefuses 234.12 Voltagetransformer 244.13 CurrentTransformer 264.14 Shuntreactor 284.15 Current-LimitingReactor 294.16 Generatorneutralgroundingdevices 304.17 Surgearrester 324.18 Bushing 344.19 Insulator 344.20 Linetrap 345 TheLayoutofHighvoltageElectricalEquipment 355.1 TheLayoutofMainElectricalEquipment 355.2 Clearancerequirement 405.3 AccessandFence 495.4 RequirementforBuildingandCivilWork 52ExplanationofWordinginThisCode 55ListofQuotedStandards 56NBXXXX-20XX1 GeneralProvisions1.0.1 Inordertostandardizetheselectionandarrangementdesignofhighvoltageelectricalequipmentinhydropowerplants,soastomakeitsafeandreliable,technologicallyadvancedandeconomicalreasonable.thiscodeisformulated.1.0.2 Thiscodeappliestotheselectionandarrangementdesignofhighvoltageelectricalequipmentwithnominalvoltagefrom3kVto750kVfornewlybuilt,reconstructedandexpandedhydropowerplants.1.0.3 Inadditiontothiscode,theselectionandarrangementdesignofhigh-voltageelectricalequipmentinhydropowerplantsshallalsocomplywiththecurrentrelevantstandardsofChina.

2 Terms2.0.1 incominglinethelineleadingfrommaintransformertohighvoltageswitchgear.2.0.2 outgoinglinethelineleadingfromhighvoltageswitchgeartohighvoltageoutgoingequipment.2.0.3 connectinglinethelineinhydropowerplantforswitchgearsofdifferentvoltagelevelsleadtoaninterconnectingtransformer,oramongswitchgearsofthesamevoltagelevelbutatdifferentlocations.2.0.4 assemblytransformerthepowertransformerneededtobedisassembled,transported,andassembledattheinstallationsiteaftervariousfactorytestsduetothelimitationoftransportation.2.0.5 take-overcurrentthecurrentattheintersectionofthetime-currentcharacteristiccurvesoftwokindsofovercurrentprotectiondevices.

3 BasicRequirements3.1 GeneralRequirements3.1.1 Theselectionandarrangementofhighvoltageelectricalequipmentshallchoosesafeandreliable,technologicallyadvancedandeconomicalreasonableproducts，Accordingtothespecificconditionsoftheprojectandlong-termdevelopment.Meanwhilethelayoutschemeshouldbeformulatedaccordingtotherequirementsofclimate,environment,geology,topography,layout,incomingandoutgoinglinemodeandequipmentmanufacturing,operation,maintenance,installationandtransportation.Theprincipleofsavinglandandenergy-savingshouldbefollowedtomeettherequirementsofenvironmentalprotection.Soastoachievereasonabledesign,reliableoperation,convenientinstallationandmaintenance.3.1.2 Highvoltageswitchgearof72.5kVandaboveshouldusegasinsulatedmetal-enclosedswitchgear(GIS).Alsocanusetheairinsulatedswitchgear(AIS)orhybridgasinsulatedmetal-enclosedswitchgear(H-GIS)accordingtospecificengineeringconditions.3.1.3 Intheselectionofincomingline,outgoinglineandconnectinglinetype,themainelectricalwiring,maintransformerlayout,switchstationtypeandlayoutshallbecomprehensivelyconsidered.3.2 Electricalrequirements3.2.1 Themaximumvoltageofthehighvoltageelectricalequipmentshouldnotbelowerthanthemaximumvoltageofthesysteminitssystem.3.2.2 Thelong-termallowablecurrentofhighvoltageelectricalequipmentshouldnotbelessthanthemaximumcontinuousworkingcurrentofthecircuitundervariouspossibleoperationmodes;Theoutdoorlayouthighvoltageelectricalequipmentshouldconsidertheinfluenceofsunlightonitscurrentcarryingcapacity.3.2.3 Thecheckofshort-circuitcurrentshallmeetthefollowingrequirements:1 Theshort-circuitcurrentvalueusedtoverifythepeakwithstandandshort-timewithstandofhighvoltageelectricalequipmentandthebreakingcurrentofcircuit-breakershouldbecalculatedaccordingtotheshort-circuitcurrentofthepowersystemdesignlevelyear；Themainelectricalwiringandoperationmodeusedinthecalculationshallbethenormalwiringandoperationmodethatthemaximumshort-circuitcurrentmayoccur.2 Theshort-circuitmode,short-circuitpointselectionandshort-circuitcurrentcalculationofthemaximumshort-circuitcurrentshallcomplywithrelevantprovisionsofthecurrentindustrystandardNB/T35043GuidelinesforShort-circuitCurrentCalculationofThree-phaseACSysteminHydropowerProjects.3 Theshort-timewithstandcurrentofhighvoltageelectricalequipmentprotectedbyfusemaynotbechecked,butthepeaktolerancecurrentshouldbechecked;Theshort-timewithstandandthepeakwithstandcurrentofthecircuitofvoltagetransformerprotectedbyfusemaynotchecked.4 Thecalculationtimeofthermaleffectofshort-circuitcurrentshallmeetthefollowingrequirements:1) Exceptcable,thecalculationtimeofthermaleffectofshort-circuitcurrentofconductorsshouldadoptthesumofthemainprotectionactiontimeandthecorrespondingcircuit-breakerbreaktime；Whenthemainprotectionhasdeadzone,whenthemainprotectionhasdeadzone,thebackupprotectionactiontimethatcanworkondeadzoneshouldbeadopted;2) Thecalculationtimeofthermaleffectofcableshort-circuitcurrentshouldadoptthesumofbackupprotectionactiontimeandcorrespondingcircuitbreakerbreaktime;forfeedercableconnectedtomotor,thecalculationtimeofthermaleffectofshort-circuitcurrentcanadoptthesumofthemainprotectionactiontimeandthecorrespondingbreakerbreaktime;3) Thecalculationtimeofthermaleffectofshort-circuitcurrentofotherelectricalequipmentsshouldadoptthesumofbackupprotectionactiontimeandcorrespondingcircuitbreakerbreaktime.3.2.4 Thefrequencyofhighvoltageelectricalequipmentsshallbedeterminedaccordingtotheratedfrequencyofthesystemandshalladapttotherangeofsystemfrequencyvariation.3.2.5 TheinsulationleveloftheelectricalequipmentsshallcomplywithrelevantprovisionsofthecurrentnationalstandardGB/T311.1InsulationCoordinationPart1:Definitions,PrinciplesandRules.3.2.6 ThetemperaturerisetestofhighvoltageswitchgearshallcomplywithrelevantprovisionsofthecurrentindustrystandardDL/T593CommonspecificationforHighvoltageSwitchgearandControlgearStandards.3.2.7 At1.1timesofthemaximumoperatingphasevoltage,electricalequipmentandfittingsshouldnothavevisiblecoronaatnightsofthesunnydays.Theradiointerferencevoltageofelectricalequipmentwithvoltageof110kVandaboveshouldnotbegreaterthan500μVinsunnydaysoutdoor;ThetestrequirementsshallcomplywithrelevantprovisionsofthecurrentnationalstandardGB/T11604Testingprocedureofradiointerferencegeneratedbyhighvoltageequipment.3.3 Mechanicalrequirements3.3.1 Theequipment,thesupportingstructureanditsfoundationshallwithstandtheexpectedmechanicalstress,normalloadandtheabnormalloadshallbeconsidered,andthemechanicalstrengthofthestructureshouldbedeterminedbythemostunfavorableloadcombination.Thecombinationofvariousloadsshallmeetthefollowingrequirements.1 Incaseofnormalloadconditions,staticload,tensionload,installationload,iceload,windload,andshort-termstressandloadduringconstructionandmaintenanceshallbeconsideredforequipment,supportstructureanditsfoundation.2 Incaseofabnormalload,switchoperatingforce,short-circuitforce,unbalancedtension,thesimultaneousactionofthemaximumaccidentalload,staticloadandtensionloadintheseismicloadshallbeconsideredfortheequipment,supportstructureanditsfoundation.3.3.2 Themaximumforceoftheelectricalequipment’sleadduringnormaloperationandshortcircuitshouldnotbegreaterthantheallowableloadoftheelectricalequipmentterminal.3.3.3 Theconductor,bushing,insulatorandfittingsofoutdoorswitchgearshallbecalculatedaccordingtothemeteorologicalconditionsofthepowerstationanddifferentstressstates.Theminimumsafetycoefficientoftheconductorandinsulatorshallnotbelessthantheprovisionsintable3.3.3.Table3.3.3 TheminimumsafetycoefficientforconductorsandinsulatorscategoryUnderlong-termLoadsUndershort-termLoadsBushing,supportinsulatoranditsfittings2.51.67Suspensioninsulatoranditsfittings42.5FlexiblewireIncomingline,outgoinglineandconnectingline.3.52.5Otherflexiblewire42.5Rigidconductor2.01.67Note:1 Thesafetycoefficientofthesuspensioninsulatorcorrespondstothe1helectromechanicaltestload.Ifcorrespondingtothefailureload,thesafetycoefficientshouldbe5.3and3.3respectively.2 Thesafetycoefficientofhardconductorcorrespondstothefailurestress.Ifthestresscorrespondstotheyieldpoint,thesafetycoefficientshouldbe1.6and1.4,respectively.3.4 Climaticandenvironmentalrequirements3.4.1 Theselectionofhighvoltageelectricalequipmentshallmeettherequirementsofairtemperature,windspeed,humidity,pollution,altitude,earthquake,icingandotheroperatingconditions.3.4.2 Theselectionofambienttemperatureforhighvoltageelectricalequipmentshouldcomplywiththeprovisionsoftable3.4.2.Table3.4.2Theselectionofambienttemperatureforhighvoltageelectricalequipment(℃)categoryLocationAmbienttemperaturemaximumtemperatureminimumtemperatureBareconductorsoutdoorMeanmaximumtemperatureofthehottestmonth—indoordesigntemperaturewithventilation—electricalequipmentSF6InsulationequipmentAnnualmaximumtemperatureTheextrememinimumtemperatureotheroutdoorequipmentthemaximumtemperatureinoneyearAnnualminimumtemperatureindoorreactorthemaximumexhausttemperatureforventilationdesigning—otherindoorlocationdesigntemperaturewithventilation—Notes:1 Theannualmaximumorminimumtemperatureshouldbetheaveragevalueoveryearsofmeasuredannualmaximumorminimumtemperature.2 Themeanmaximumtemperatureofthehottestmonthreferstotheaveragevalueofthemonthlyaveragevalueofthehottestmonthoveryears.3 Ifthereisnoventilationdesigntemperaturedatafortheselectionoftheambienttemperatureofbareconductorsandotherelectricalequipmentintheroom,theaveragemaximumtemperatureinthehottestmonthplus5℃canbeselected.3.4.3 Whentheambienttemperatureislowerthantheminimumallowabletemperatureofthehighvoltageelectricalequipment,thehighvoltageelectricalequipmentshouldbeequippedwithheatingdeviceorthermalinsulationmeasures.3.4.4 Inareaswithserioussnowingandicing,thehighvoltageelectricalequipmentshouldbetakenmeasurestopreventaccidentscausedbysnowandice.3.4.5 Forthehighvoltageelectricalequipmentwithambientairtemperaturehigherthan40℃,thetestvoltageofitsexternalinsulationinthedrystateshouldbemultipliedbythetemperaturecorrectioncoefficient,whichcanbecalculatedbythefollowingformulas: (3.4.5)whereKt isthetemperaturecorrectioncoefficientT istheambientairtemperature(℃)3.4.6 Themaximumwindspeedusedintheselectionoftheelectricalequipmentfortheoutdoorswitchgearshallmeetwiththefollowingprovisions:1 For500kVand750kVvoltagelevelofswitchgear,the10minaveragemaximumwindspeed,10mheightabovethegroundandoncein50years,shallbeadopted.2 Forthevoltagelevelof330kVandbelow,the10minaveragemaximumwindspeed,10mheightabovethegroundandoncein30years,canbeadopted.3 Whentheheightofconductorsandelectricalequipmentismorethan10mabovetheground,themaximumwindspeedshouldbecorrectedaccordingtotheinstallationheightoftheconductorandelectricalequipment.whichcanbemadeaccordingtotherelevantformulasofthecurrentindustrystandardDL/T5158Technicalcodeformeteorologicalsurveyinelectricpowerengineering.4 Whenthemaximumwindspeedexceeds34m/s,correspondingmeasuresshallbetakenforoutdoorswitchgearlayout.3.4.7 Therelativehumidityofthehighvoltageelectricalequipmentshouldmeetthefollowingrequirements:1 Whensettinguptheventilationfacilities,therelativehumidityshouldbeselectedaccordingtothedesignforventilation.2 Whennoventilationfacilitiesaresetup,therelativehumidityoftheworkingenvironmentforhighvoltageelectricalequipmentshouldbetheaveragerelativehumidityofthelocalmonthwiththehighesthumidityinthepowerplant.3 Incaves,undergroundandhumidplaceswithhighhumidity,therelativehumidityofthehighvoltageelectricalequipmentshouldbetheactualrelativehumidity.4 Withnorelevantinformation,therelativehumidityofthehighvoltageelectricalequipmentenvironmentcanbe95%.3.4.8 TheseismicdesignofhighvoltageelectricalequipmentshouldcomplywithrelevantprovisionsofthecurrentnationalstandardGB50260Codesforseismicdesignofelectricalinstallations.3.4.9 Forelectricalequipmentinstalledatanaltitudehigherthan1000m,whenthetestofexternalinsulationwithstandvoltageisconducted,theactualwithstandvoltageappliedtotheexternalinsulationoftheequipmentshouldbemultipliedbytheelevationcorrectionfactorKa,Kashouldbecalculatedbythefollowingformulas : （3.4.9）whereKa istheelevationcorrectioncoefficientH istheelevationofequipmentinstallationsite（m）q isthevalueoftheindexshouldconformtorelevantprovisionsofthecurrentnationalstandardGB/T311.1Insulationco-ordinationPart1:Principles,definitionsandrules.3.4.10 Theclassificationofon-sitepollutiongradeandtheuniformcreepagedistanceshouldcomplywithrelevantprovisionsofthecurrentnationalstandardGB/T26218.1Selectionanddimensioningofhighvoltageinsulatorsintendedforuseinpollutedconditions--Part1:Definitions,informationandgeneralprinciples.

4 TheSelectionofHighvoltageElectricalEquipment4.1 Conductor4.1.1 Thetypeofconductorshouldbeselectedaccordingtotherequirementsofvoltagegrade,loopcurrent,environmentalconditionsofpowerstation,sitelayout,installationandmaintenance,projectinvestment,etc.4.1.2 Thegeneratorvoltagecircuitbuscanadoptisolatedphaseenclosedbus,commonenclosurebus,solidinsulatedtubularbus-bar,cableandopenbus.Thetypeselectionshouldmeetthefollowingrequirements:1 Forthegeneratorvoltagebus,whentheratedcurrentofthecircuitisnomorethan4000A,commonenclosurebusshouldbeselected,andsolidinsulatedtubularbus-barcanbeusedwhenthelayoutsiteisnarrow.Whentheratedcurrentofthecircuitismorethan4000A,thecontinuousenclosuretypeisolated-phasebusshouldbeselected.Whentheratedcurrentofthecircuitisnomorethan6300A,andthelayoutisnarrow,solidinsulatedtubularbus-barcanalsobeused.2 Themaingeneratorvoltagebusoflightbulbtubularturbineunitscanbecable,commonenclosurebusorsolidinsulatedtubularbus-bar.3 Thetypeselectionofgeneratorvoltagecircuitbusshouldbeconsideringconvenientlyconnectedwithothergeneratorvoltageequipment.4 Whenthemainbusofthegeneratorvoltagecircuitadoptscable,itisappropriatetochoosethesingle-core,copper-coreXLPEcable.Thevoltagebetweencablecoreandinsulationshieldormetalsheathshouldbe173%oftheworkingphasevoltageofthecircuit.OthertechnicalrequirementsshouldcomplywithrelevantprovisionsofthecurrentnationalstandardGB50217Standardfordesignofcablesofelectricalengineering.5 Whenthegeneratorvoltagecircuitadoptsopenbus,openbuscanbeusedfor4000Aandbelow,andtroughbuscanbeusedfrom4000Ato8000A.6 Thegeneratorvoltagebranchcircuitbusshouldbeofthesametypeasthemaincircuitbus.4.1.3 Theconductorsof110kVandaboveHighvoltageswitchgearcanbehighvoltagecable,gasinsulatedmetal-enclosedtransmissionline(GIL),tubularbus-bar,Flexiblewire,etc.Inplaceswherethelines,outgoinglines,connectinglinesinoverheadlinesaredifficulttoberealized,highvoltagecablesandGILcanbeusedthroughtechnicalandeconomiccomparison.Thetechnologicalandeconomiccomparisonshouldconsidertheconductorcapacity,civilstructure,operationandmaintenance,investmentandsoon.4.1.4 Theselectionofisolated-phasebusshouldmeetthefollowingrequirements:1 Theselectionoftechnicalparametersofisolated-phasebusshouldbeselectedcomplywithrelevantprovisionsofthecurrentnationalstandardGB/T8349Metal-enclosedBus.2 Isolated-phasebusmaybeprovidedwithtemperaturemeasuringdevicesformonitoringthetemperatureofconductors,jointsandenclosuresatjointsorotherlocationspronetooverheating.3 Theconnectionbetweentheisolated-phasebusandthelightningarrestercabinet,thevoltagetransformercabinetandtheneutralequipmentcabinetshouldbethroughtheinsulatingbushortheseparatortopreventthefaultinthecabinetfromaffectingthebus.4 Detachableconnectionsshouldbeusedbetweentheenclosureofisolated-phasebusandtheenclosureofequipmentsexceptthegeneratorcircuitbreakerandthephase-changingswitch.Theenclosureofisolated-phasebusshouldbeinsulatedandvibrationisolatedfromtheenclosureofequipments.5 Atthelong-straightline,differentfoundation,connectionsectionandequipmentjointofisolated-phasebus,compensationdevicesforthermal-expansion-cold-contraction,orforfoundationsettlementshouldbeset,itsconductorusescopperbraided,thinaluminum,copperlaminatedexpansionjointsorotherequivalentconnectionmodes,theenclosureadoptsrubberexpansionsleeve,aluminumcorrugatedpipeorotherequivalentconnectionmodes.6 Theisolated-phasebuscanbeequippedwithanti-condensationdevicesatappropriatepositions.,naturallycoolingmetal-enclosedbus,shouldbeequippedwithofthesealinginsulationsleeveorothermeasures,inthesiteofinsideandoutsidethroughthewall,topreventinternalandexternalairconvectionintheenclosureandproducecondensation.7 Theisolated-phasebusshouldbeequippedwithathree-phaseshort-circuittestdevice,anditsarrangementshallbeconvenientforgeneratorshort-circuittest.8 Thecontinuousenclosuretypeisolated-phasebusshouldbeequippedwithashort-circuitboardattheenclosurewheretheconnectionpointwithotherequipmentotherthanthegeneratorcircuitbreaker,andthethree-phaseshort-circuittestconnector.9 Theenclosureofisolated-phasebusandthemetalpartsofthesupportingstructureshouldbereliablygrounded.10 Theenclosureofthecontinuousisolated-phasebuscanbegroundedatmultiplepointsoratonepoint.Thegroundingconductorshouldmeettherequirementsofpeakwithstandcurrentandshort-timewithstandcurrent11 Whentheshort-circuitcurrentpassesthroughthebus,theinductivevoltageofitsenclosureshouldnotexceed24V.4.1.5 Theselectionofthecommonenclosurebusshallmeetthefollowingrequirements:1 TheselectionoftechnicalparametersofthecommonenclosurebusshouldcomplywithrelevantprovisionsofthecurrentnationalstandardGB/T8349Metal-enclosedBus.2 thecommonenclosurebusshouldbenaturallycooled.3 Thecommonenclosurebusshouldadoptaluminumenclosure,ofwhichtheratedcurrentisgreaterthan2500A.4 Theoutdoorinstalledcommonenclosurebusshouldbeabletowithstandthewind,rainandsunshinewithoutaffectingthecontinuousoperationofthebus;Anypartoftheenclosureshouldnotaccumulatewater,andtheenclosureshouldbeprovidedwiththenecessaryfilterscreendrainagedevice.5 Thethicknessofthecommonenclosurebusenclosureshouldnotbelessthan4mm,andtheenclosureshouldbestrongenoughtoavoiddeformationduetothestresscausedbytheinstallationerror.6 Thecommonenclosurebusshouldbeabletocompensatetheconductorandtheenclosureforthedifferentsettlementanddisplacementwithin50mmduetothetemperaturechangeandthedifferentialsettlementofthefoundation.Thestraightsectionofnon-segregatedphasebusshouldbeequippedwithexpansionjointsinabout20m-bayandatdifferentfoundationstructures.7 Theremovablepart,coverandinspectionholeofthecommonenclosurebusenclosureshouldbeprovidedwitharubbersealwasherinitsoutdoorpart.Whentheenclosureoritssupportingstructureisdisplacedbyvibration,temperaturechangeorshort-circuitelectricalforce,thegasketshouldnotbemovedordamaged,andthesealgasketshouldbeabletobeusedforalongtimewithoutreplacementoradjustment.8 Theenclosureofcommonenclosurebusandtheequipmentshouldbeinsulatedfromeachotherandadoptdetachableconnection.4.1.6 Theselectionofsolidinsulatedtubularbus-barshouldmeetthefollowingrequirements:1 Thetechnicalparametersofsolidinsulatedtubularbus-barshouldbeselectedcomplywithrelevantprovisionsofthecurrentindustrystandardDL/T1658Solidinsulatedtubularbus-barofvoltageuptoandincluding35kV.2 Themetalshieldofsolidinsulatedtubularbus-barsystemshouldbeinsulatedinsections,andeachsectionshouldbesinglygrounded.3 Thesupportsandhangersofthesolidinsulatedtubularbus-barandthefixedfittingsshouldbemadeofnon-magneticmaterials.4 Foreachphaseexpansionjointsofsolidinsulatedtubularbus,flexibleconnectionshallbeprovidedattheconnectionpointwithotherequipments.4.1.7 Theselectionofopenbusshouldmeetthefollowingrequirements:1 TheopenbusshouldbeselectedcomplywithrelevantprovisionsofthecurrentindustrystandardDL/T5222Designtechnicalruleforselectingconductorandelectricalequipment.2 non-electrifiedmetalcomponentssuchasthesupportinsulatorbaseoftheopenbus,theflangeofthebushing,theprotectivenet(cover)andothershouldbegroundedreliably.3 Inadditiontomeetingtherequirementsofelectricalandmechanicalstrength,whentheworkingcurrentoftheconductorisgreaterthan1500A,thesupportingsteelmembersandconductorsupportingsplintofeachphaseconductorshallnotformaclosedmagneticcircuit;Whentheworkingcurrentoftheconductorisgreaterthan4000A,theadjacentsteelmembersoftheconductorshouldtakemeasurestoavoidformingaclosedmagneticcircuitorinstallingashortcircuitring.4.1.8 Theselectionofhighvoltagecableshouldmeetthefollowingrequirements:1 TheselectionoftechnicalparametersandlayingrequirementsofhighvoltagecablesshouldcomplywithrelevantprovisionsofthecurrentnationalstandardGB50217Standardfordesignofcablesofelectricalengineering,andcurrentindustrystandardsDL/T5222DesigntechnicalruleforselectingconductorandelectricalequipmentandDL/T5228CodeforthedesignofAC110kV~500kVpowercablesystemforhydro-powerstation.2 CabletypeshouldchooseXLPEinsulatedcable.3 ThemetalsheathofACsingle-corepowercableshallbedirectlygroundedatleastatoneend,andthemaximumnormalinductivepotentialofanynon-groundedendshouldmeetthefollowingrequirements:1) ThemaximumnormalinducedpotentialofACsinglecorepowercableshallnotbegreaterthan50Vwhennosafetymeasuresaretakentoeffectivelypreventpersonnelfromcontactingthemetalsheathatwill.2) ThemaximumnormalinducedpotentialofACsinglecorepowercableshallnotbegreaterthan300Vwhensafetymeasuresaretakentoeffectivelypreventpersonnelfromcontactingthemetalsheathatwill.4.1.9 Theselectionoftubularbusbarshouldmeetthefollowingrequirements:1 Thetubularbusbarshouldbeselectedaccordingtothecontinuousworkingcurrentandcheckedaccordingtotheshort-timetolerancecurrent.2 Thetubularbusbarshouldhavesufficientmechanicalstiffnessandstrengthtoavoidbreezevibrationandendeffects.3 Tubularbusbarshouldbeeasyformanufactureandinstall.4 Forthemechanicalcalculationofoutertubularbus,theconductorloadcombinationconditionscanbespecifiedintable4.1.9.Table4.1.9 ConductorloadcombinationconditionconditionwindspeeddeadloaddownleadweightIceweightShortcircuitelectromotiveforceseismicforceNormaltimeThewindspeedwhenthereisice√√√——Themaximumwindspeed√√———Short-circuittimeThe50%ofmaximumwindspeedandnotlessthan15m/s√√—√—EarthquaketimeThe25%ofmaximumwindspeed√√——TheforceofanearthquakeofthecorrespondingmagnitudeNote：√Istheloadconditiontobeusedinthecalculation.5 Inthedesignofoutertubularbus-bar,thefollowingformulashouldbeusedtocheckthebreezevibrationcausedbyKarmanvortexwind: （4.1.9）wherevjs isthecomputedwindspeedinwhichatubularbusproducesabreezeresonance(m/s);f isthenaturalfrequenciesofeachorderoftheconductor(Hz);D istheOuterdiameterofconductor(m);A istheFrequencycoefficient,canbetakenas0.214.6 Intheabsenceoficeandwind,thedeflectionwithythespanofthesupportedtypesinglealuminumtubularbus-barshouldnotexceed0.5%ofthebusspan,andthedeflectionofthesplit-structurealuminumtubularbus-barshouldnotexceed0.4%ofthebusspan,andalsoshouldnotbegreaterthan0.5to1.0conductordiameter.7 Thesettingoftubularbusgroundingpointshallensurethatthevoltageinducedbytheadjacentrunningbusontheinspectionbusshouldnotexceed50V8 Theexpansionjointshouldbesetupreasonablyincombinationwiththesupportandfixationmodeofthetubularbus.4.1.10 Theselectionofflexiblewireshouldmeetthefollowingrequirements:1 Thesectionandstructuretypeofflexiblewireshouldbeselectedaccordingtoenvironmentalconditions,circuitloadcurrent,corona,radiointerferenceetc.,andalsothepeakwithstandcurrentandshort-timewithstandcurrentshallbeverified.2 Inthecoastalareaswithhighsaltcontentintheairortheplaceswherethesurroundinggashasobviouscorrosiontotheconductor,theanticorrosion