IEC61000-3-2:2018/AMD1:2020/ISH1:2021–1–©IEC2021ICS33.100.10INTERNATIONALELECTROTECHNICALCOMMISSION____________IEC61000-3-2Edition5.02018-01Amendment12020-07ELECTROMAGNETICCOMPATIBILITY(EMC)–Part3-2:Limits–Limitsforharmoniccurrentemissions(equipmentinputcurrent≤16Aperphase)INTERPRETATIONSHEET1Thisinterpretationsheethasbeenpreparedbysubcommittee77A:EMC–Lowfrequencyphenomena,ofIECtechnicalcommittee77:Electromagneticcompatibility.Thetextofthisinterpretationsheetisbasedonthefollowingdocuments:DISHReportonvoting77A/1106/DISH77A/1114/RVDISHFullinformationonthevotingfortheapprovalofthisinterpretationsheetcanbefoundinthereportonvotingindicatedintheabovetable.IMPORTANT–The"colourinside"logoonthecoverpageofthisdocumentindicatesthatitcontainscolourswhichareconsideredtobeusefulforthecorrectunderstandingofitscontents.Usersshouldthereforeprintthisdocumentusingacolourprinter.___________IEC61000-3-2:2018-01/AMD1:2020-07/ISH1:2021-08(en-fr)–2–IEC61000-3-2:2018/AMD1:2020/ISH1:2021©IEC2021InterpretationofthesecondsetofrequirementsapplicabletoClassCequipmentwitharatedpower≥5Wand≤25Waccordingto7.4.3ofIEC61000-3-2:2018andIEC61000-3-2:2018/AMD1:2020.IntroductionThesecondsetofrequirementsof7.4.3ofIEC61000-3-2:2018andIEC61000-3-2:2018/AMD1:2020requiresthat“thewaveformoftheinputcurrentshallbesuchthatitreachesthe5%currentthresholdbeforeorat60°,hasitspeakvaluebeforeorat65°anddoesnotfallbelowthe5%currentthresholdbefore90°,referencedtoanyzerocrossingofthefundamentalsupplyvoltage”andthat“Componentsofcurrentwithfrequenciesabove9kHzshallnotinfluencethisevaluation(afiltersimilartotheonedescribedin5.3ofIEC61000-4-7:2002andIEC61000-4-7:2002/AMD1:2008maybeused);”TestinglaboratoriesandClassCequipmentmanufacturersconcludedthatseveralharmonicstestsystemswithIEC61000-4-7compliantmeasurementequipmentdonotcompletelyfilteroutthecomponentsofcurrentwithfrequenciesabove9kHz,thusresultinginanon-accurateevaluationofthephaseangles(seeFigure1).Oneofthereasonswhyfiltersarenotusedisthattheycanalterthephaseangleitselfbyintroducingaphasedelay.QuestionWhenapplyingthesecondsetofrequirementsin7.4.3,whatmethodshallbeusedtomeasurethephaseangleinordertoavoidtheinfluenceofcomponentsofcurrentwithfrequenciesabove9kHz?InterpretationGiventheissuesreportedbytestlaboratories,ifthephaseangleismeasuredwithanIEC61000-4-7testsystemthatdoesn’tremovethecomponentsabove9kHzcorrectly,themeasurementswithadigitaloscilloscopeshallprevail,wherethecomponentsabove9kHzhavebeenremovedwithoutaffectingthephaseangleatwhichthepeakcurrentoccurs.NOTEThiscanbeachievedforexamplebyusingasynchronousaveragingmodeoftheoscilloscope(seeFigure2).IEC61000-3-2:2018/AMD1:2020/ISH1:2021–3–©IEC2021AnnexFigure1andFigure2showanincorrectandthecorrectevaluationofthephaseangle.Figure1–IncorrectmeasurementFigure2–Correctmeasurementwithaveragedwaveform
