电气工程及其自动化 外文翻译 外文文献 英文文献 短路电流

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1、Short-circuitcurrent1TermsandDefinitionsThefollowingtermsanddefinitionscorrespondlargelytothosedefinedinIEC60909.Refertothisstandardforalltermsnotusedinthisbook.Thetermsshortcircuitandgroundfaultdescribefaultsintheisolationofoperationalequipmentwhichoccurwhenliv

2、epartsareshuntedoutasaresult.lCauses:1.Overtemperaturesduetoexcessivelyhighovercurrents.2.Disruptivedischargesduetoovervoltages.3.Arcingduetomoisturetogetherwithimpureair,especiallyoninsulators.lEffects:1.Interruptionofpowersupply.2.Destructionofsystemcomponents

3、.3.Developmentofunacceptablemechanicalandthermalstressesinelectricaloperationalequipment.lShortcircuit:AccordingtoIEC60909,ashortcircuitistheaccidentalorintentionalconductiveconnectionthrougharelativelylowresistanceorimpedancebetweentwoormorepointsofacircuitwhic

4、harenormallyatdifferentpotentials.lShortcircuitcurrent:AccordingtoIEC60909,ashortcircuitcurrentresultsfromashortcircuitinanelectricalnetwork.Itisnecessarytodifferentiateherebetweentheshortcircuitcurrentatthepositionoftheshortcircuitandthetransferredshortcircuitc

5、urrentsinthenetworkbranches.lInitialsymmetricalshortcircuitcurrent:Thisistheeffectivevalueofthesymmetricalshortcircuitcurrentatthemomentatwhichtheshortcircuitarises,whentheshortcircuitimpedancehasitsvaluefromthetimezero.lInitialsymmetricalshortcircuitapparentpow

6、er:Theshortcircuitpowerrepresentsafictitiousparameter.Duringtheplanningofnetworks,theshortcircuitpowerisasuitablecharacteristicnumber.lPeakshortcircuitcurrent:Thelargestpossiblemomentaryvalueoftheshortcircuitoccurring.lSteadystateshortcircuitcurrent:Effectiveval

7、ueoftheinitialsymmetricalshortcircuitcurrentremainingafterthedecayofalltransientphenomena.lDCaperiodiccomponent:Averagevalueoftheupperandlowerenvelopecurveoftheshortcircuitcurrent,whichslowlydecaystozero.lSymmetricalbreakingcurrent:Effectivevalueoftheshortcircui

8、tcurrentwhichflowsthroughthecontactswitchatthetimeofthefirstcontactseparation.lEquivalentvoltagesource:Thevoltageatthepositionoftheshortcircuit,whichistransferredtoth