1automation measurement tehconolg.docx
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1automation measurement tehconolg.docx
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1automationmeasurementtehconolg
Introduction
1、Thestatusandroleofmodernmeasuringtechnology
Thetestistoknowtheworldandtransformtheworldhumanindispensableimportantmeans.Measurementscienceandtechnologyisasignificantfieldofengineeringinterestinitsownright,ratherthanadjuncttospecialtyareas.
Measurementisanimportantwaytorecognizetheworldforpeople,itsimprovementimpelsthedevelopmentofscienceandengineer,inturn,thelatterbringsimpetustotheformer.
Anationalmodernizationlevelistousetomeasurethelevelofautomation,intheautomationtechnology,modernmeasurementtechnologyalsohasanextremelyimportantpositionandrole.
AutomaticdetectionsystemblockdiagramAutomaticcontrolsystemsimplifiedblockdiagram
Throughtheabovetwodiagramscanbefound,Modernmeasuringtechnologyisalsotheimportantpillaroftheautomationtechnology.
2、sensor
sensoristhedevicewhichisusedtoconvertingnon-electricitydeterminetoelectricitydetermine.Innon-electricquantitymeasurement,thesensoristheessentialelement.
3、Thecompositionprincipleofmeasuringinstrumentandsystem
Measurementsarepeoplewithspecialtechnologyandequipment,throughtheexperimentmethodtoachieveacertainnumberofobjectivethingsinformationprocess.Speciallyusedformeasuringinstrumentorsystemknownasmeasuringinstrumentormeasuringsystem,itsbasictaskfromthemeasuredobjectismeasured,andthemeasurementresultsshowmeasurer.Soitshouldincludeatleastthreebasiccomponents:
feelthemeasuredsensor,themeasurementresultsshowadisplayandcontactwiththemeasurementcircuit.
Microcomputer,rapidlyappliedinthefieldoftesting,formedanewgenerationautomatedtestsystem-microcomputertestingsystem.
4、Theresearchcontentofthiscourseandthenature
①Tomastertheuseofvarioussensors
②Familiarwiththecharacteristicsofvarioussensorsandapplicationenvironment
③Graspthetypicalmeasurementcircuit
④Accordingtoacertainphysicalquantities,toconstructasystemofmeasurement
Chapter1Current,voltageandpowermeasurement
1.1Themeasurementofcurrent
1.1.1Directmeasurementmethodbyammeter
Directcurrentmeasurementusingammeter,needtopayattentiontodistinguishbetweendirectcurrentoralternatingcurrent.Dcammeterisusedtotestthedccurrent,accurrentmetertomeasureaccurrent.
Nowlaboratorytousemultimeterforcurrentmeasurements.Ifyouwanttomeasurethecurrentbymultimeter,thefirstyoumustknowthecurrentisACorDA;thesecondyoumustchoicethegeartomeasure.Ifyoudon'tsuitableranges,thefusewillburnout.Sothebestrangefrombigtosmall.
1.1.2Current,voltagetransformationmethod
①Samplingresistancemethod
ThesmallstandardresistaristhestringinthemeasuredcurrentloopcalledtheSamplingresistancemethod.riscalledthesamplingresistance.Forexample,
Eisthesystempowersupply,IXisthemeasuredcurrent.accordingtotheprincipleofVirtualshortandbroked,
so
so
Throughtheaboveformula,wecanobtaintheloadcurrent.
②Currentfrequencyconversionmethod
Thecurrentisconvertedintofrequencymeasurement,thismethodiscalledCurrentfrequencyconversionmethod.Use555timerofcurrent,frequencyconverter,isarelativelysimplesolution.
InputcurrenttothevoltagechargingcapacitanceCrise,whenthresholdisreached,theoutputisbacktozero,atthesametimethedischargeendofshortcircuit,capacitordischargequickly.Oncethecapacitorvoltageislowerthanthetriggervalue,theoutputtobecomeahighlevel,thedischargeendopencircuit,capacitorrecharge,repeattheaboveprocess.
Current,frequencyconversioncoefficientK,
canbecalculatedaccordingtothetype.
1.1.3Currenttransformer
Currenttransformerisgenerallyusedinthemeasurementofalternatingcurrent.Currenttransformerissimilartothetransformerisalsoaccordingtotheprincipleofelectromagneticinductiontowork,isthevoltageandcurrenttransformeroftransformertransformationtransformiscurrent.Currenttransformerbywindingofthemeasuredcurrent(N1)numberofturnsandiscalledtheprimarywinding(ortheoriginalwinding,primarywinding);Bymeasuringthewinding(numberofturnsforN2)iscalledthesecondarywinding(orvicewinding,thesecondarywinding).
PrimarysidecurrentI1,TheoriginaledgenumberofturnsisN1,ViceedgenumberofturnstoN2,soViceedgecurrentI2,
IfyouwanttomeasuretheI2bycontroller,Signalconditioningisneeded.Usingpeakdetectioncircuit,acsignalintodcsignal.
U2onbehalfofthecurrenttransformeroutputsignal,passamplitudedetectioncircuit,Cangetalternatingcurrentamplitude.
1.2Voltagemeasurement
1.2.1Dcvoltagemeasurement
①Multimetermeasurement
IfyouwanttomeasuretheDCvoltagebymultimeter,thefirstyoushouldchoicetherightgear,thesecondyoumustknowtheprobeparallelintwosidetobetested.
②Digitalcontrollermeasurement
IfyouwanttomeasurethedcvoltagebyMCU,thefirstyoushouldknowthescopeofvoltage,becausetheadconvertionhavebigscopeofvoltageistheirreferencevoltage.thesecondyoushouldknowthemeasurementaccuracy,thisgivesyoutheselectedAD.
Instrumentationamplifierisusedinthismethod.Instrumentationamplifierisusedtoenlargethedifferentialmodesignal,eliminatethecommonmodesignal.
Theimplementationofspecificblockdiagramisasfollows:
Dcvoltageacquisitionsimulationdiagram
1.2.2Acvoltagemeasurement
Potentialtransformer isveryvitaldeviceforAcvoltagemeasurement.now,Iwilltellyoutheworkingprincipleofpotentialtransformer.
Iftheacvoltageisbig,youmustusethepotentialtransformertobuckthevoltage.
LCTV31CEisaCurrentvoltagetransformer,sothesecondaryisn’tallowopentouse.Thetypicalcircuitdiagramisasfollows:
Outputvoltageissmall,somustusingamplificationcircuit,thelaterputthesignalintoAmplitudedetectioncircuit.
Wavedisplay:
Whyprimarysignalcannotdisplaycomplete?
Throughthesimulation,wemustknowwhatisAmplitude,peaktopeakvalues,thevalidvalues.Therelationsbetweenthreeshouldbeclear.
1.3Powermeasurement
①Powermetermeasurepower
Firstly,weshouldknowwhatisthepowermeter.Powermetercanonlybeusedtomeasureacpower.PowermetercanonlybeusedtomeasureActivepower.Powermeterhastwocoilsinside,oneisavoltagecoil,otheriscurrentcoil.Notewith"*"(asterisk)shouldconnectthepowersupplyside.
Weneedtoclearseveralconcepts.ApparentpowerisProductofRMSvoltageandcurrenteffectivevalueoftheport.Activepower,instantaneouspowerreferstoacycleofintegralmeanvalue.Reactivepowerisbyreactor(inductororcapacitor)inaccircuits,duetoitsattheendsofthevoltageandthecurrenthasanAngleof90degreesoutofphasetoflowthrough,socan'twork,alsonotactivepowerconsumption,butitinvolvedwiththepowerofenergyexchange,thusproducingreactivepower,reducestheefficiencyofgeneratorsandpowergridpowersupply.
Apparentpower:
Activepower:
Reactivepower:
Accordingtothesimulationdiagram;
YoumustknowthePowermetermeasuretheRSMofvoltageandcurrent.
②usetheadconverttomeasurethepower
Accordingtotheprincipleofpowermeasurement,firstlyyoumustmeasuretheRSMofvoltage,
SecondlyyouneedtomeasuretheRSMofcurrent.MCUgettheparameterandthencalculate,
AndMCUcontroldisplay.
ThepictureaboveR2isaSamplingresistor,byMonitoringitssecondterminalvoltagethenyouwillhavethecurrentpasstheload(R1).
Canalsouseadedicatedpowerchipismeasured,justasCS5460A.
Summary:
1.Thedifferencebetweendcandac
2.Acvoltageandaccurrentmeasurement
3.Dcvoltageanddccurrentmeasurement
4.Powermeasurement
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