Designation:A912/A912M−11StandardTestMethodforAlternating-CurrentMagneticPropertiesofAmorphousMaterialsatPowerFrequenciesUsingWattmeter-Ammeter-VoltmeterMethodwithToroidalSpecimens1ThisstandardisissuedunderthefixeddesignationA912/A912M;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoverstestsforvariousmagneticpropertiesofamorphousmaterialsatpowerfrequencies[25to400Hz]usingatoroidaltesttransformer.Theterm“toroidaltesttransformer”isusedtodescribethetestdevice,reservingtheterm“specimen”torefertothematerialusedinthetest.Thetestspecimenconsistsoftoroidallywoundflatstrip.1.2Thistestmethodcoversthedeterminationofcoreloss,excitingpower,rmsandpeakexcitingcurrent,severaltypesofacpermeability,andrelatedpropertiesunderacmagnetizationatmoderateandhighinductionsatpowerfrequencies[25to70Hz].1.3Withproperinstrumentationandspecimenpreparation,thistestmethodisacceptableformeasurementsatfrequenciesfrom5Hzto100kHz.Properinstrumentationimpliesthatalltestinstrumentshavetherequiredfrequencybandwidth.AlsoseeAnnexA2.1.4Thistestmethodalsoprovidesproceduresforcalculat-ingimpedancepermeabilityfrommeasuredvaluesofrmsexcitingcurrentandforcalculatingacpeakpermeabilityfrommeasuredpeakvaluesoftotalexcitingcurrentatmagneticfieldstrengthsuptoabout10Oe[796A/m].1.5Explanationsofsymbolsandbriefdefinitionsappearinthetextofthistestmethod.TheofficialsymbolsanddefinitionsarelistedinTerminologyA340.1.6ThistestmethodshallbeusedinconjunctionwithPracticeA34/A34M.1.7Thevaluesandequationsstatedincustomary(cgs-emuandinch-pound)unitsorSIunitsaretoberegardedseparatelyasstandard.Withinthisstandard,SIunitsareshowninbrackets.Thevaluesstatedineachsystemmaynotbeexactequivalents;therefore,eachsystemshallbeusedindependentlyoftheother.Combiningvaluesfromthetwosystemsmayresultinnonconfo...
