【英文标准名称】:Short-circuitcurrentsinthree-phasea.csystems-Currentsduringtwoseparatesimultaneousline-to-earthshort-circuitsandpartialshort-circuitcurrentsflowingthroughearth
【原文标准名称】:三相交流系统中的短路电流.两条独立线路同时对地短路和部分短路电流流入大地时的电流
【标准号】:BSEN60909-3-2010
【标准状态】:现行
【国别】:英国
【发布日期】:2010-04-30
【实施或试行日期】:2010-04-30
【发布单位】:英国标准学会(GB-BSI)
【起草单位】:BSI
【标准类型】:()
【标准水平】:()
【中文主题词】:定义(术语);双线接地短路;电网;电气工程;电气设备;电学;故障电流;高电压;线路接地短路;低电压;数学计算;架空线;还原比率;短路阻抗;短路;短路电流;单相电路;符号;三相电流;三相电力网
【英文主题词】:Definitions;Doubleline-to-earthshort-circuits;Electricpowernetworks;Electricalengineering;Electricalequipment;Electricity;Faultcurrents;Highvoltage;Line-to-earthshort-circuits;Lowvoltage;Mathematicalcalculations;Overheadpowerlines;Reductionratio;Shortcircuitimpedance;Shortcircuits;Short-circuitcurrents;Single-phasecircuits;Symbols;Three-phasecurrent;Three-phasenetworks
【摘要】:ThispartofIEC60909specifiesproceduresforcalculationoftheprospectiveshort-circuitcurrentswithanunbalancedshortcircuitinhigh-voltagethree-phasea.c.systemsoperatingatnominalfrequency50Hzor60Hz,i.e.:a)currentsduringtwoseparatesimultaneousline-to-earthshortcircuitsinisolatedneutralorresonantearthedneutralsystems;b)partialshort-circuitcurrentsflowingthroughearthincaseofsingleline-to-earthshortcircuitinsolidlyearthedorlow-impedanceearthedneutralsystems.Thecurrentscalculatedbytheseproceduresareusedwhendetermininginducedvoltagesortouchorstepvoltagesandriseofearthpotentialatastation(powerstationorsubstation)andthetowersofoverheadlines.Proceduresaregivenforthecalculationofreductionfactorsofoverheadlineswithoneortwoearthwires.Thestandarddoesnotcover:a)short-circuitcurrentsdeliberatelycreatedundercontrolledconditionsasinshortcircuittestingstations,orb)short-circuitcurrentsintheelectricalinstallationsonboardshipsoraeroplanes,orc)singleline-to-earthfaultcurrentsinisolatedorresonantearthedsystems.Theobjectofthisstandardistoestablishpracticalandconciseproceduresforthecalculationofline-to-earthshort-circuitcurrentsduringtwoseparatesimultaneousline-to-earthshortcircuitsandpartialshort-circuitcurrentsthroughearth,earthwiresofoverheadlinesandsheathsorshieldsofcablesleadingtoconservativeresultswithsufficientaccuracy.Forthispurpose,theshort-circuitcurrentsaredeterminedbyconsideringanequivalentvoltagesourceattheshort-circuitlocationwithallothervoltagesourcessettozero.Resistancesofearthgridsinstationsorfootingresistancesofoverheadlinetowersareneglected,whencalculatingtheshort-circuitcurrentsattheshort-circuitlocation.ThisstandardisanadditiontoIEC60909-0.Generaldefinitions,symbolsandcalculationassumptionsrefertothatpublication.Specialitemsonlyaredefinedorspecifiedinthisstandard.Thecalculationoftheshort-circuitcurrentsbasedontherateddataoftheelectricalequipmentandthetopologicalarrangementofthesystemhastheadvantageofbeingpossiblebothforexistingsystemsandforsystemsattheplanningstage.Theprocedureissuitablefordeterminationbymanualmethodsordigitalcomputation.Thisdoesnotexcludetheuseofspecialmethods,forexamplethesuper-positionmethod,adjustedtoparticularcircumstances,iftheygiveatleastthesameprecision.AsstatedinIEC60909-0,short-circuitcurrentsandtheirparametersmayalsobedeterminedbysystemtests.
【中国标准分类号】:K04
【国际标准分类号】:17_220_01;29_020;29_240_20
【页数】:60P.;A4
【正文语种】:英语


【英文标准名称】:ISOgeneralpurposemetricscrewthreads.Tolerances.Part3:deviationsforconstructionalscrewthreads.
【原文标准名称】:ISO一般用途米制螺纹.公差.第3部分:结构螺纹的偏差
【标准号】:NFE03-054-1999
【标准状态】:现行
【国别】:法国
【发布日期】:1999-03-01
【实施或试行日期】:1999-03-20
【发布单位】:法国标准化协会(FR-AFNOR)
【起草单位】:
【标准类型】:()
【标准水平】:()
【中文主题词】:
【英文主题词】:Bolts;CGSsystem;Design;Designations;Diameter;Dimensionaldeviations;Dimensionaltolerances;Dimensions;Externalthreads;Formtolerances;Internalthreads;ISOscrewthreads;Limitdimensions;Nuts;Screwthreads;Screws(bolts);Threads;Tolerances(measurement)
【摘要】:
【中国标准分类号】:J04
【国际标准分类号】:21_040_10
【页数】:20P.;A4
【正文语种】:其他