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.Thetermsshortcircuitandgroundfaultdescribefaultsintheisolationofoperationalequipmentwhichoccurwhenlivepartsareshunte

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

3、chanicalandthermalstressesinelectricaloperationalequipment.lShortcircuit:AccordingtoIEC60909,ashortcircuitistheaccidentalorintentionalconductiveconnectionthrougharelativelylowresistanceorimpedancebetweentwoormorepointsofacircuitwhicharenormallyatdifferentpotentials.lShortcircu

4、itcurrent:AccordingtoIEC60909,ashortcircuitcurrentresultsfromashortcircuitinanelectricalnetwork.Itisnecessarytodifferentiateherebetweentheshortcircuitcurrentatthepositionoftheshortcircuitandthetransferredshortcircuitcurrentsinthenetworkbranches.lInitialsymmetricalshortcircuitc

5、urrent:Thisistheeffectivevalueofthesymmetricalshortcircuitcurrentatthemomentatwhichtheshortcircuitarises,whentheshortcircuitimpedancehasitsvaluefromthetimezero.lInitialsymmetricalshortcircuitapparentpower:Theshortcircuitpowerrepresentsafictitiousparameter.Duringtheplanningofne

6、tworks,theshortcircuitpowerisasuitablecharacteristicnumber.lPeakshortcircuitcurrent:Thelargestpossiblemomentaryvalueoftheshortcircuitoccurring.lSteadystateshortcircuitcurrent:Effectivevalueoftheinitialsymmetricalshortcircuitcurrentremainingafterthedecayofalltransientphenomena.

7、lDCaperiodiccomponent:Averagevalueoftheupperandlowerenvelopecurveoftheshortcircuitcurrent,whichslowlydecaystozero.lSymmetricalbreakingcurrent:Effectivevalueoftheshortcircuitcurrentwhichflowsthroughthecontactswitchatthetimeofthefirstcontactseparation.lEquivalentvoltagesource:Th

8、evoltageatthepositionoftheshortcircuit,whichistransferredtoth