仪表与量测ppt课件

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1、Chapter2MeasurementofCurrentandVoltageI.ZoltanBasicConsiderationsMeasureingNetworksSignalConvertersTypesofMeterMeasuringInstrumentsBasicConsiderationsDirectVoltageDirectCurrentMeanValueMeanAbsoluteValueRoot-mean-square(rms)vaulePeanValueInstantaneousValueVectorComponentsFrequencySpectrumBasics-Rang

2、esofCurrentMeasurementsACDMMDCDMMElectromechanicalammeters1fA1pA1nA1µA1mA1A1kA1MA1aADCelectrometersExtendersBasics-RangesofVoltageMeasurements1nV1µV1mV1V1kV1MVDCnanovoltmetersDCDMMACElectromechanicalvoltmetersExtendersBasics-Voltage/CurrentMeasurementModelDUTESC-1ESC-nMLSC-1SC-mV/AMeasuringinstrume

3、ntInterferencesourcesDUT-DeviceundertestESC-ExternalSignalConvertersML-MeasuringLeadsSC-InternalSignalConvertersV/A-metersMeasuringNetworks-SourceSourceMeasuringLeadsMeasuringInstrumentUIVoltageSourceCurrentSourceINOUTINOUTIdealNonidealMeasuringNetworks-MeasuringLeadsSourceMeasuringLeadsMeasuringIn

4、strumentMeasuringNetworks-MetersSourceMeasuringLeadsMeasuringInstrumentVVoltmeterHLAHLAmmeterMeasuringNetworks-LoadingError-VMeterUVMeasuringNetworks-LoadingError-IMeterIAMeasuringNetworks-AsymmetricNetworkUVINGroundVoltageDifferencescauseextraerrorGround(earth)isaconductingconnectionbywhichanelect

5、ricalcircuitorelectricalequipmentisconnectedtotheearthortosomeconductingbodyofrelativelylargeextentthatservesinplaceofearth.MeasuringNetworks-Symmetric-multiplegroundedUVHLdistrubingcurrentcausedbydifferentgroundingpotentialMeasuringNetworks-Symmetric-SinglegroundedUVHLMeasuringNetworks-CommonModeV

6、oltageUa)b)IACommonmodevoltage(voltage/currentsourcearealwaysfloatingontopofit)MeasuringNetworks-EffectofCommonModeVoltageUVINHLCommonmodevoltagehasnoeffectonlywhenZgiszero.MeasuringNetwork-CommonModeVoltagePreventionUVHLGGuardshieldGuardShieldMeasuringNetwork-CommonModeVoltagePreventionDoubleGuard

7、ShieldVHLGGuardshieldINGroundshieldMeasuringNetwork-InterferenceSourcesSignalsourceMeasuringleadCGMeasuringinstrumentHLUInterferencesourceILoadMG:StrayCapacitanceC:StrayResistanceM:MutualInductanceMeasuring