美国电压等级

NeutralHIGHLEGDELTAThreePhaseNeutralWYEThreePhaseTNeutralTHREE-WIRESinglePhase()TechnicalPaperDipl.-Ing.WolfgangEsserExportrelevantvoltageinformationandmainsformsinNorthAmerica2AnearliercompilationofthenormalmainsformsandconventionalvoltagesinNorthAmericashowamultitudeoflocalvariations.Thisisduetothehistoricalstructure,butalsowiththehugedimensionsofthecontinent,thedistancesbetweenenergyresourcelocationsandloadcentresandthehighcurrentdemandsandtheindividualneedsofpowersuppliers.Withsuchamultiplicityitisimpossibletodealeconomicallyaswellastechnically.ThestandardANSI1C84.1hasbroughtalargereductioninconventionalvoltagesandisaclearexampleoftherevisingeffectsofstandards.Thestandardhadthetaskofcoordinatingthedifferinginterestsoftheenergyproducersanddistributorsontheonesideandtheelectricityconsumerontheotherside,e.g.bythedeterminationoftolerances.Whereastheenergyproduction,energytradinganddistributionwasinthepastinonehand,todaytheyaremostlytheresponsibilityofvariouscompanygroupseachwiththeirownbusinessinterests.TherearestilltodayinAmericaregionaldifferencesofenergyproduction.Theexportingsupplierofmachinesorsystems(OEM2)withassociatedelectricalequipmentshouldquicklyandbindinglydiscussthenetworkconditionswiththefinalsystemuser.Themainssystemvoltageaswellasthemainssystemformhaveaninfluenceontheselectionanduseoftheswitchingandprotectiondevices.Deltamainssystemsorunearthedstar-deltamainssystemsexcludesomemodern,Europeansolutions.Specialistaswellasnon-expertsaredependantuponthecorrectvoltagedetails.SelectionofthecorrectvoltageinNorthAmericaisnotonlytoomuchformanyholidaymakers,butalsowithspecialiststhereisoftendoubtswiththeexportingofmachinesandsystems.Thisisduetothefactthatdifferentvoltagedetailsareoftengiven(ServiceVoltageorUtilizationVoltage,NominalSystemVoltageorRatedVoltageandfinallytheMotorNameplateVoltage),thatwedonotdifferentiateintheIECworld.IntheIECworld,fromproductionto1ANSI=AmericanNationalStandardsInstitute,Inc,=OriginalEquipmentManufactureruse,wetalkaboutopertingvoltageandassumethecompliancewiththetoleranceforvoltagedrop.InGermanythevoltageisanelectricalparameterthatwedonotneedtothinktoomuchabout.Thisessayisconcernedexclusivelywithlowvoltagesinpublicandindustrialmainssystemsandtheirsuppliedcommercialandindustrialequipment.ItdetailsextractsofimportantinformationfortheprojectengineersofcompaniesexportingtoAmerica.Bindinginformationisdetailedin„AmericanNationalStandardforElectricPowerSystemsandEquipment–VoltageRatings(60Hertz),ANSIC84.1-2006“orforCanadatheCSA3Standard„CAN-3-C235-83“.ServiceVoltageandUtilizationVoltageInthisessayonlythelowvoltagerangeisconsidered.InNorthAmericathatincludesallvoltageswithavalueofupto1000V(Increasedto1200VbyANSIC84.1-2006).Above1000V(1200V)iscalledmediumvoltageandhighvoltage.OnlyACvoltagesareconsideredthatcanalsoappearasACsystems.Theratedfrequencyforallvoltagesisuniformly60Hz.Alldescribedvoltagesandtolerancesareforcontinuousoperationwithoutconsiderationofshort-timealterationsduetoswitchingprocessesorthestart-upoflargemotors.Heavyorlongstart-updrivescanleadinindividualcasestothenecessityforspecialstartingtypesandconductordimensionstomaintainthespecifiedtolerances.WhereasintheIECworldweworkwiththeuniformdescriptionoperatingvoltage(comparableinAmerica:NominalSystemVoltageorRatedVoltage),inNorthAmericaitisdifferentiatedbetweendifferentlynamedvoltagesinthedistribution/supplynetworkandintheconsumersystem.TheServiceVoltageisthevoltageinthesupplynetwork.Theirtolerancesmustbeespecially3CSA=CanadianStandardsAssociation,´sconductorsandtheconductorsoftheenduser.Thatis,houseconnectionboxes(pointofconnection,pointofcommoncoupling).Theelectricitysupplycompanyisresponsibleforthequalityofthisvoltage.TheactualServiceVoltageisnormallybetween95...105%ofit´snominalvoltage.Whenconsideringthevoltagetoleranceitmustbetakenintoaccountthatinlargeamericanstatestherearemorespurconductorsysteminsteadofcompactnetworkmainssystemsthatallowahighersupplysafetyandahighervoltagestability.TheUtilizationVoltageisthevoltageintheconsumer´smainssystem,especiallytheeffectivevoltageattheconnectionpointoftheequipment.TheUtilizationVoltagecanfluctuateintheworstcasebetween87...106%oftheratedvoltage.ThedifferencebetweentheminimumServiceVoltageandtheminimumUtilizationVoltageisthepermittedvalueoftheVoltagedropinsidetheconsumersystem.Thesystemoperatorandtheelectricalinstallerareresponsibleforthequalityofthisvoltagebyhiscorrectdimensioningoftheconductors.Thepermissable5%maximumvoltagedropaccordingtoNEC4(FeederCircuit+BranchCircuit)isnormallydividedbetweenavoltagedropof3%uptotheincomer(FeederCircuit)and2%fortheconsumerinstallation(BranchCircuit).Withthetoleranceofbothvoltageswedecidebetweenanideallevel(RangeA)andastilltolerablelevel(RangeB).VoltagesintheRangeBshouldbelimitedinthefrequencyaswellasthedurationoftheiroccurrance.Thereishowevernobindingspecificationforthislimitationaswellasfortheoccurrenceofvoltage