仪表与量测ppt课件_4

《仪表与量测ppt课件_4》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、MeasurementofPowerandEnergyGy.KoranyiMeasuredQuantitiesInstrumentsofPowerMeasurementMeasurementofElectricalPowerMeasurementofElectricalEnergyIntroductionThemeasurementofElectricalpowerandenergyisimportantinthefollowingaspects.energydistribution,accounting,regulationofpo

2、werconsumption,supervisionofelectricalmachineinvestigationofeffectivenessThediscussedmethodsfocusontheapplicationinthelinefrequencyrange(50-60Hz)But,methodsarealsoapplicabletohigherfrequency.MeasuredQuantities-DefinitionofpowerInstantaneousPower:AveragePower:DCPower:Pow

3、erofR:SinusoidalVoltageandCurrent:InstantaneousPoweroflinearnetwork:ActivePower:ReactivePower:ApparentPower:MeasuredQuantities-DefinitionofpowerNonSinusoidalActivePower:NonsinusoidalReactivePower:NonsinusoidaApparentPower:AnotherConcept-ReactivePowerPowerFactor:Dthedist

4、ortedpowerfromtheinnerproductofdifferentharmonicsMeasuredQuantities-DefinitionofpowerMultiplePhaseNetwork:ThreePhaseSystem:ComplexPower:ApparentPower(EulerFormula)DefinitionofEnergy:PowerInstrument-ElectromechanicalElectromechanicalpowermeterrealizethemultiplicationbyma

5、gneticfieldandcurrentinthemovingcoil.Therearetwocoils:Excitationcoil(currentcoil)formagneticfiled(B)Movingcoil(voltagecoil)forneedlemovement.RiandRvaretheinternalresistanceofthecoils.DeflectionangleisthemultiplicationnofthemagneticfieldBandcurrentinthemovingcoil(Iv).Tap

6、A:TapB:BA12PowerMeter-Electronic-AnalogMultiplierElectronicpowermeterrealizethemulitplicationandaveragingofvoltageandcurrentbyelectronicdevices.Thereareanalog,digital,orhybridconstructionformultiplication.UxandUyarethevoltageandcurrentmeasurement.UxandUyaremultiplied(K)

7、andintegratedbytheLPF.YXKVPowerMeter-Electronic-AnalogMultiplierAYXKVRZVoltagetransformerCurrentTransformerPowerMeter-TimeDivisionMultiplierUxandUyrepresentthevoltageandcurrentmeasured.UsisthepulsewidthmodulationofUy.ItisusedtoswitchbetweenUxand-Ux.Tgismuchsmallerthanth

8、eperiodofUxandUysuchthat,UxandUycanberegardedasconstant.AftertheintegrationbytheLPF,theoutputispropotionaltoth