实验指针万用表的使用-Experiment Using t

实验：指针万用表的使用

Experiment:UsingtheAnalogMultimeter实训目的TrainingObectives:学习认识万用表的结构Understandthestructureofananalogmultimeter.01掌握指针式是万用表的使用注意事项Learntheprecautionsforusingananalogmultimeter.0203掌握用万用表测量电阻的方法Masterthemethodofmeasuringresistancewithamultimeter.1、MF-47指针式万用表的结构I.StructureoftheMF-47AnalogMultimeter1-表笔插孔Probejacks2-晶体管插孔Transistorsocket3-读数装置（表头）Readingdevice(meterhead)4-机械调零旋钮Mechanicalzeroadjustmentknob

5-欧姆调零旋钮Ohmszeroadjustmentknob6-挡位旋钮Rangeselectorknob2.指针式万用表的使用方法UsingtheAnalogMultimeter（1）使用前的检查与调整InspectionandAdjustmentBeforeUse1.指针式万用表的外观应完好无损，在其轻轻摇晃时，指针应摆动自如。旋动挡位旋钮，应切换灵活无卡阻，且挡位准确。Theanalogmultimetershouldbeingoodcondition,andthepointershouldmovefreelywhengentlyshaken.Rotatingtherangeselectorknobshouldswitchsmoothlywithoutsticking,andtherangesshouldbeaccurate.2.在测量前，先检查红、黑表笔插接的位置是否正确。红表笔接红色接线柱或标有“＋”的插孔内，黑表笔接黑色接线柱或标有“－”的插孔内。Beforemeasurement,checkiftheredandblacktestprobesarecorrectlyinserted.Theredtestprobeshouldbeconnectedtotheredterminalorthesocketlabeledwitha"+"symbol,whiletheblacktestprobeshouldbeconnectedtotheblackterminalorthesocketlabeledwitha"−"symbol.3.在红、黑表笔接至被测电路前，务必查看所选挡位与测量对象是否相符，避免挡位和量程的误用造成无法获取测量结果，甚至损坏万用表。Beforeconnectingtheredandblacktestprobestothecircuitundertest,verifythattheselectedrangematchesthemeasurementobject.Thispreventsincorrectrangeselectionandmisuse,whichcouldleadtoinaccuratemeasurementsordamagetothemultimeter.4.水平放置指针式万用表，转动表头下方的机械调零旋钮，使指针对准弧线刻线左边的零位线，避免读数出现较大的误差。Placetheanalogmultimeterhorizontallyandrotatethemechanicalzeroadjustmentknoblocatedunderthemeterhead.Alignthepointerwiththezeroreferencelinetoavoidsignificantreadingerrors.2.指针式万用表的使用方法UsingtheAnalogMultimeter5.测量电阻前，需经由欧姆调零旋钮实施调零操作（每换挡1次均应进行调零操作）。调零操作时，先将挡位旋钮扳至欧姆挡适合位置，再使红、黑表笔短接，转动欧姆调零旋钮，使指针对准欧姆刻线右边的零位线。若指针始终不能指向零位线，则应更换万用表的后备电池。Whenmeasuringresistance,performazeroadjustmentusingtheohmszeroadjustmentknob(performthisadjustmenteverytimeyouchangetherange).Todothis,settherangeselectorknobtotheappropriateohmsrange,short-circuittheredandblacktestprobes,andthenrotatetheohmszeroadjustmentknobuntilthepointeralignswiththezeroreferencelineontherightsideoftheohmsscale.Ifthepointerconsistentlyfailstopointtothezeroreferenceline,replacethebackupbatteryofthemultimeter.2.指针式万用表的使用方法UsingtheAnalogMultimeter(2)万用表使用方法(2)OperatingProceduresfortheMultimeter1.先水平放置万用表，并机械调零。Placethemultimeterhorizontallyandperformthemechanicalzeroadjustment.2.根据测量参数要求，插入红、黑表笔，黑表笔接入COM公用端，红表笔接入＋、2500V、10A或mA插孔。Dependingonthemeasurementparameters,inserttheredandblacktestprobes.ConnecttheblacktestprobetotheCOMcommonterminalandtheredtestprobetothe+,2500V,10A,ormAsocket.3.选择挡位及量程（电压、电流或电阻等）。每选择1次欧姆挡时，均应进行欧姆调零操作。Selecttheappropriaterangeandscale(voltage,current,orresistance,etc.).Zeroadjustmentshouldbeperformedeachtimetheohmsrangeisselected.2.指针式万用表的使用方法UsingtheAnalogMultimeter4.将万用表红、黑表笔连接于被测电路中，注意串联或并联、直流参数的极性等。Connecttheredandblacktestprobestothecircuitundertest,payingattentiontotheseriesorparallelconnectionandthepolarityofDCparameters,ifapplicable.5.根据选择的挡位及量程读取数值。Readthevaluesbasedontheselectedrangeandscale.6.测量完毕，挡位旋钮扳至交流电压最大挡、空挡或OFF挡。若长时间不用，应取出内部电池。Aftermeasurement,turntherangeselectorknobtothemaximumACvoltagerange,theoffposition,orOFF.Ifnotinuseforanextendedperiod,removetheinternalbattery.2.指针式万用表的使用方法UsingtheAnalogMultimeter(3)电阻测量的关键步骤。(3)KeyStepsforResistanceMeasurement1.断开被测电路的电源及连接导线。被测电阻所处电路务必断电，并使之与其他元器件的连接导线断开——即被测电阻不能存在并联支路。Disconnectthepowersourceandconnectingwiresfromthecircuitundertest.Thecircuitcontainingtheresistortobemeasuredmustbede-energized,anditsconnectionswithothercomponentsshouldbedisconnected—meaningthattheresistortobemeasuredshouldnothaveanyparallelbranches.2.指针式万用表的使用方法UsingtheAnalogMultimeter2.挡位及量程的选择。先粗略估计所测电阻的阻值，再选择合适的量程。若被测电阻不能估计其值，一般是将挡位旋钮扳至R×100或R×1k的位置初测后，观察指针是否停在欧姆刻度线中心值附近：是表示挡位合适，指针太靠零表示挡位需要减小，指针太靠无穷大（∞）表示挡位需要增大。SelectingtheRangeandScale.Initially,estimatetheapproximateresistancevaluetobemeasured,andthenchoosetheappropriatescale.Iftheresistancevaluecannotbeestimated,startbysettingtherangeselectorknobtotheR×100orR×1kposition.Observewhetherthepointerstopsnearthecentervalueoftheohmsscale:ifitdoes,itindicatesthecorrectrange;ifthepointeristooclosetozero,therangeneedstobedecreased,andifthepointeristooclosetoinfinity(∞),therangeneedstobeincreased.2.指针式万用表的使用方法UsingtheAnalogMultimeter3.正确测量电阻。将量程选定且欧姆调零完毕的指针式万用表的红、黑表笔分别紧密接触被测电阻的两端，双手不可同时触至表笔的金属部分及电阻被测端，以免引入的人体电阻造成较大的测量误差。ProperResistanceMeasurement.Ensurethattherangeisselected,andtheohmszeroadjustmentiscomplete.Makesuretheredandblacktestprobesoftheanalogmultimetermakegoodcontactwiththetwoendsoftheresistorundertest.Avoidtouchingthemetalpartsofthetestprobesandthemeasuredterminalsoftheresistorsimultaneouslywithyourhandstopreventintroducingsignificantmeasurem