1、毕业设计（论文）外文翻译原文题目DIGITALVOLTMETERDIGITALVOLTMETERBACKGROUNDOFTHEINVENTIONTHISINVENTIONGENERALLYRELATESTOVOLTAGEMEASUREMENTDEVICES,ANDMOREPARTICULARLYTODIGITALVOLTMETERSCAPABLEOFMEASURINGACANDDCVOLTAGESWITHAUTOMATICSELECTIONOFTHEPROPERMEASUREMENTFUNCTIONSOASTOPROVIDEASAFEMEASURINGINSTRUMENTTHEDIGITALV
2、OLTMETEROFTHEINVENTIONMAYALSOPROVIDEAMEASURINGINSTRUMENTWHICHISSUBSTANTIALLYINSENSITIVETOTHEEFFECTSOFDISTRIBUTEDCAPACITANCE,FORACCURATEANDRELIABLEVOLTAGEMEASUREMENTMANYSITUATIONS,FROMCHECKINGANDTESTINGOFELECTRICALSERVICEINSTALLATIONSTOCHECKINGTHEINTEGRITYOFRESIDENTIALWIRING,REQUIRETHEUSEOFVOLTAGEMEA
3、SURINGEQUIPMENTCAPABLEOFMEASURINGTHEMAGNITUDEOFANACLINEVOLTAGE,DCVOLTAGEORCOMBINATIONTHEREOFITSHOULDBEEVIDENTTHATINTHEVERIFICATIONOFELECTRICALSERVICEVOLTAGE,VERYHIGHVOLTAGESMAYBEENCOUNTERED,MAKINGROUTINEPOWERMEASUREMENTAPOSSIBLYDANGEROUSACTIVITYFORPROVIDINGSUCHMEASUREMENTCAPABILITIES,THEREHAVEBEENDE
4、VELOPEDANUMBEROFAC/DCVOLTAGEREADINGVOLTMETERSORMUFTIFUNCTIONMETERSADAPTEDTOMEASUREVOLTAGEINCONJUNCTIONWITHOTHERELECTRICALPARAMETERSINTHISRESPECT,VARIOUSACANDDCANALOGVOLTMETERSHAVEBEENDEVELOPEDWHICHOPERATEWITHAGALVANOMETERTYPEMETERSTOINDICATETHEMAGNITUDEOFTHEVOLTAGEBEINGMEASUREDMANYOFTHESEANALOGTYPEI
5、NSTRUMENTSAREDEFICIENTINTHATTHEYHAVELOWINPUTIMPEDANCEANDTHEREFOREREQUIREASUBSTANTIALAMOUNTOFELECTRICALCURRENTTODEFLECTTHEMETER,WHICHWILLDISTORTTHEVOLTAGEMEASUREMENTINMANYCASESDIGITALVOLTMETERSHAVEALSOBEENDEVELOPEDWHICHMAYAVOIDTHEINACCURACYOFSOMEANALOGMETERS,BUTINTURNHAVEOTHERRECOGNIZEDDEFICIENCIESBO
6、THANALOGANDDIGITALVOLTMETERSARESUBJECTTOINACCURACY,AREBULKY,FRAGILEANDTHEUSERTHEREOFISPOSSIBLYDANGEROUSMANYSUCHMETERSINCLUDERANGEANDFUNCTIONSELECTIONSWITCHESWHICHAREMANIPULATEDBYTHEUSERTHEVOLTMETERMUSTBECAPABLEOFMEASURINGVOLTAGESOVERAWIDERANGEOFMAGNITUDES,WHICHWILLREQUIRETHEUSERTOHAVEKNOWLEDGEOFWHAT
7、VOLTAGESARETOBEEXPECTEDIFTHEWRONGFUNCTIONORRANGEISSELECTEDONAVOLTMETER,THEREISTHEPOSSIBILITYTHATANOVERVOLTAGECOULDCAUSETHEMEASURINGINSTRUMENTTOEXPLODEUPONAPPLICATIONTOAVOLTAGESOURCEADDITIONALPROBLEMSCANBEENCOUNTEREDWHENANELECTRICIANOROTHERUSERATTEMPTSTOUSEANACVOLTMETERTOCLEARADCLINEUNDERAMISCONCEPTI
8、ONOFWHETHERAPARTICULARLINECARRIESACORDCLINEVOLTAGE,ORADCVOLTAGEWITHANACRIPPLEINOTHERSITUATIONS,SUCHASCHECKINGTHEINTEGRITYOFRESIDENTIALWIRING,THEMEASUREMENTOFTHEVOLTAGEBETWEENTHELINEANDLOADCONNECTIONSOFAMETERBASEWITHTHERESIDENTIALSWITCHINTHEOPENPOSITIONISPERFORMEDINTHESEANDOTHERSITUATIONS,DISTRIBUTED
9、CAPACITANCEPRESENTONTHELINEMAYINHIBITACCURATEMEASUREMENTSWITHAVOLTMETERMOSTDIGITALVOLTMETERSASWELLASAFEWANALOGVOLTMETERSCANNOTBEUSEDWHERESIGNIFICANTCAPACITIVEEFFECTSAREPRESENTA“PARASITIC“CURRENTFLOWSTHROUGHTHEMETERWHICHRETURNSTOGROUNDTHEDISTRIBUTEDFREESPACEANDINTERCONDUCTORCAPACITANCEOFTHELOADWIRING
10、ALTHOUGHSENSITIVEVOLTMETERSAREABLETOMEASURETHIS“PARASITIC“CURRENT,THEPRESENCEOFTHISCURRENTWILLRESULTINAMBIGUOUSREADINGSASTOTHECONDITIONOFTHELOADWIRINGALOWIMPEDANCEVOLTMETERMAYAVOIDTHEEFFECTSOFDISTRIBUTEDCAPACITANCETOSOMEDEGREE,BUTHAVETHEDEFICIENCIESASMENTIONEDPREVIOUSLYWITHRESPECTTOACCURACYOFVOLTAGE
11、MEASUREMENTSINYETOTHERSITUATIONS,ELECTRICALCONTINUITYMEASUREMENTSAREDESIREDTOBEMADEWITHAVOLTMETER,BUTSUCHMEASUREMENTSMAYCOMPROMISETHEVOLTAGEMEASUREMENTCAPABILITIESOFTHEMETERFOREXAMPLE,CONTINUITYMEASUREMENTSMAYBEMADEWITHASOLENOIDTYPEMETER,BUTACCURACYOFTHEVOLTAGEMEASUREMENTSISCOMPROMISEDTHEPRIORARTVOL
12、TAGEMEASURINGEQUIPMENTHASGENERALLYBEENFOUNDTONOTBEASRELIABLEORASSAFEASDESIRED,ANDHASLACKEDTHEFLEXIBILITYTOPERFORMVARIABLEMEASUREMENTOPERATIONSINANEASYANDACCURATEMANNERSUMMARYOFTHEINVENTIONBASEDUPONTHEFOREGOING,THEREHASBEENFOUNDANEEDTOPROVIDEAVOLTAGEMEASURINGAPPARATUSWHICHOVERCOMESTHEDEFICIENCIESOFTH
13、EPRIORARTANDPROVIDESASAFEANDEASYTOUSEMETERFORMEASURINGTHEMAGNITUDESOFVOLTAGESINAVARIETYOFAPPLICATIONSITISTHEREFOREAMAINOBJECTOFTHEINVENTIONTOPROVIDEAVOLTAGEMEASURINGINSTRUMENTWHICHAUTOMATICALLYSELECTSACORDCOPERATIONTOELIMINATETHEPOSSIBILITYOFUSERSELECTIONERRORS,TOMAKEUSEOFTHEVOLTMETERSAFEANDCONVENIE
14、NTITISANOTHEROBJECTOFTHEINVENTIONTOPROVIDEAVOLTAGEMEASURINGINSTRUMENTWHICHWILLAUTOMATICALLYMEASUREEITHERACORDCVOLTAGES,ANDDISPLAYTHEMAGNITUDEOFTHEVOLTAGEMEASURED,THECURRENTTYPEANDPOLARITYOFTHESIGNALBEINGTESTEDANOTHEROBJECTOFTHEINVENTIONISTOPROVIDEAVOLTAGEMEASURINGINSTRUMENTWHICHISSUBSTANTIALLYINSENS
15、ITIVETOTHEEFFECTSOFDISTRIBUTIVECAPACITANCEINALINEBEINGTESTEDSTILLANOTHEROBJECTOFTHEINVENTIONISTOPROVIDEAVOLTAGEMEASURINGAPPARATUSWHICHALLOWSCONTINUITYMEASUREMENTSTOBEAUTOMATICALLYMADEWITHOUTSACRIFICINGTHEVOLTAGEMEASUREMENTCAPABILITIESOFTHEAPPARATUSANOTHEROBJECTOFTHEINVENTIONISTOPROVIDEAVOLTAGEMEASUR
16、INGINSTRUMENTWHICHINCLUDESAVARIETYOFSAFETYFEATURESDESIGNEDTOELIMINATEPOSSIBLESHOCKOREXPLOSIONDUETOVOLTAGETRANSIENTSOROVERVOLTAGESFOREXAMPLETOACCOMPLISHTHESEOBJECTSASWELLASOTHERS,THEVOLTAGEMEASURINGINSTRUMENTOFTHEINVENTIONGENERALLYCOMPRISESSIGNALCONDITIONINGCIRCUITRYCOUPLEDTOINPUTPROBES,WHICHMAYTHEMS
17、ELVESINCLUDEINTEGRALFUSESFORADDEDPROTECTIONAGAINSTOVERVOLTAGESTHESIGNALCONDITIONINGCIRCUITRYINCLUDESANAMPLIFICATIONSTAGEADAPTEDTOFILTERANDATTENUATESIGNALSINTRODUCEDTHROUGHTHEINPUTPROBESTHESESIGNALSARETHENCONNECTEDTOCIRCUITRYDESIGNEDTOTESTFORBOTHACANDDCVOLTAGESSOASTOPOSITIVELYINDICATEWHENNOVOLTAGEISP
18、RESENTINATESTCIRCUITTHISCIRCUITWILLALSODETERMINEIFBOTHACANDDCVOLTAGESAREPRESENT,ANDWILLDISPLAYTHELARGESTVOLTAGEPRESENTUPONACOMPARISONOFTHEDCMAGNITUDEAGAINSTPEAKACVOLTAGESOASTOIDENTIFYANDDISPLAYTHESTRONGESTVOLTAGEPRESENTINTHETESTEDCIRCUITTHECIRCUITRYFORALTERNATINGOPERATIONOFTHEVOLTAGEMEASURINGDEVICEB
19、ETWEENACANDDCMODESINCLUDESLOGICCIRCUITRYADAPTEDTOMONITORTHEINPUTSIGNALTODETERMINEWHETHERTHEREISATRANSITIONTHROUGHZEROVOLTSINAREPEATEDFASHIONINDICATINGANACCOMPONENTLOGICCIRCUITRYISALSOPROVIDEDFORANAPPROPRIATEINDICATIONOFWHETHERANACORDCVOLTAGEHASBEENMEASURED,THESTATUSOFTHEBATTERYPOWERASWELLASOTHEROPER
20、ATIONALCHARACTERISTICSOFTHEVOLTMETERAPOWERSUPERVISIONCIRCUITISUSEDTOAUTOMATICALLYTURNOFFTHEVOLTMETERAFTERAPREDETERMINEDAMOUNTOFTIMEORIFBATTERYPOWERFALLSBELOWAPREDETERMINEDLEVELWHICHWOULDCOMPROMISETHEINTEGRITYOFVOLTAGEMEASUREMENTSTAKENWITHTHEINSTRUMENTALTERNATIVELY,THEVOLTAGEMEASURINGAPPARATUSMAYINCL
21、UDESIGNALCONDITIONINGCIRCUITRYWHICHALLOWSTHEVOLTMETERTOSIMULATEALOWIMPEDANCETYPEMETERWHILEMAINTAININGOVERVOLTAGEPROTECTIONTOPREVENTTHEPOSSIBILITYOFEXPLOSION,VIBRATIONORMELTDOWNOFTHECIRCUITRYDURINGROUTINEPOWERMEASUREMENTSTHEABILITYTOSIMULATEALOWIMPEDANCEVOLTAGEMEASURINGDEVICEENABLESTHEEFFECTSOFDISTRI
22、BUTIVECAPACITANCETOBEMINIMIZEDWHILENOTSIGNIFICANTLYIMPACTINGONTHEACCURACYOFVOLTAGEREADINGSTAKENWITHTHEINSTRUMENTINTHISEMBODIMENT,ASHUNTINGIMPEDANCEISPOSITIONEDACROSSTHEINPUTTERMINALSOFTHEVOLTAGEMEASURINGAPPARATUSSOASTODIVERTMOSTPARASITICCURRENTRESULTINGFROMDISTRIBUTIVECAPACITANCEINSUCHACASE,OVERVOLT
23、AGEPROTECTIONISPROVIDEDBYOTHERCIRCUITCOMPONENTSINADESIREDMANNERADDITIONALLY,ACONTINUITYMEASURINGCIRCUITMAYBEPROVIDED,TOYIELDANINDICATIONOFWHETHERCONTINUITYEXISTSINATESTEDCIRCUITTHEINPUTVOLTAGEISDIRECTEDTOAWINDOWCOMPARATOR,WHEREINTHECONTINUITYFUNCTIONWILLBEACTIVATEDIFTHEMEASUREDVOLTAGELIESBETWEENAPRE
24、DETERMINEDLOWVOLTAGERANGETHECONTINUITYFUNCTIONANDCIRCUITISADAPTEDTOINTRODUCEACURRENTINTOTHETESTCIRCUITTODETERMINEIFTHEREISAVOLTAGEDROPWHICHOCCURSINTHETESTCIRCUITINDICATINGACONDITIONOFNOCONTINUITYSUCHACONTINUITYMEASUREMENTMAYBEPERFORMEDASADISTINCTPROCEDUREFROMVOLTAGEMEASUREMENTANDMAYBEAUTOMATICALLYPE
25、RFORMEDIFTHEMEASUREDVOLTAGELIESWITHINAPREDETERMINEDLOWVOLTAGERANGEASYETANOTHERALTERNATIVE,THEVOLTAGEMEASURINGAPPARATUSMAYBEPROVIDEDWITHATRUERMSMEASURINGCIRCUITTOMEASURETHEROOTMEANSSQUARERMSVALUEOFACOMPLEXACVOLTAGEWAVEFORMASPARTBFTHESIGNALCONDITIONINGCIRCUITRY,ACSIGNALSWILLBECONVERTEDTOATRUERMSSIGNAL
26、SUITABLEFORDIGITALDISPLAYTHESIGNALPROCESSINGCIRCUITRYWILLPROCESSACINPUTSIGNALSSOASTOCONVERTTHETRUERMSVALUEOFTHECOMPLEXACWAVEFORMTOADCVALUEWHICHMAYTHENBEPROCESSEDTO如ELDTHERMSVALUEOFTHEWAVEFORMTRUERMSMEASUREMENTUSINGTHEVOLTAGEMEASURINGAPPARATUSALLOWSCOMPENSATIONFORHARMONICDISTORTIONSWHICHMAYOCCURWHENN
27、ONLINEARLOADSFORMAPORTIONOFTHETESTCIRCUITTHEVOLTAGEMEASURINGAPPARATUSOFTHEINVENTIONISSAFEANDEASYTOUSEWHILEBEINGACCURATEANDPROVIDINGAVARIETYOFMEASURINGCAPABILITIESBRIEFDESCRIPTIONOFTHEDRAWINGSTHEOBJECTSANDADVANTAGESOFTHEVOLTAGEMEASURINGAPPARATUSWILLBECOMEAPPARENTUPONAFURTHERREADINGOFTHEDETAILEDDESCRI
28、PTIONOFPREFERREDEMBODIMENTS,INCONJUNCTIONWITHTHEDRAWINGS,WHEREINFIG1ISAPERSPECTIVEVIEWOFTHEVOLTAGEMEASURINGINSTRUMENTOFTHEINVENTIONFIG2ISABLOCKDIAGRAMOFAFIRSTEMBODIMENTOFTHEVOLTAGEMEASURINGINSTRUMENTINACCORDANCEWITHTHEPRESENTINVENTIONFIGS3AAND3BFORMACIRCUITDIAGRAMFORTHEEMBODIMENTASSHOWNINFIG2FIG4SHO
29、WSABLOCKDIAGRAMOFANALTERNATEEMBODIMENTOFTHEVOLTAGEMEASURINGAPPARATUSOFTHEINVENTIONANDFIGS5AAND5BANDFORMACIRCUITDIAGRAMFORTHEEMBODIMENTOFTHEINVENTIONASSHOWNINFDETAILEDDESCRIPTIONOFTHEINVENTIONTURNINGNOWTOFIG1,THEVOLTAGEMEASURINGAPPARATUS10OFTHEINVENTIONISSHOWNTOBEAHANDHELDINSTRUMENTINCLUDINGAHOUSING1
30、2WITHADISPLAY14ANDANON/OFFSWITCH16THEREONTESTLEADS18ARECOUPLEDWITHTHEINTERNALCIRCUITRYOFTHEVOLTMETER,ANDPOSITIVEANDGROUNDPROBES20AREPROVIDEDFOREASYACCESSTOATESTCIRCUITTHEHOUSING12MAYINCLUDEAPROBEHOLDER22TOPERMITTWOHANDOPERATION,ANDTHETESTLEADS18AREPREFERABLYPERMANENTLYSECUREDWITHINTHECASE12INASTRAIN
31、RELIEVEDASSEMBLYTHEPERMANENTLYSECUREDTESTLEADSFACILITATEPREVENTINGSHOCKANDELECTRICALFLASHESCAUSEDBYBANANAPLUGCONNECTORSASSOCIATEDWITHTHEPROBESOFAVOLTMETERADDITIONALLY,THEPROBETIPSMAYBESHIELDEDBYSPRINGLOADEDRETRACTINGSLEEVESTOINSURESAFEOPERATIONOFTHEAPPARATUSASWILLBEHEREINAFTERDESCRIBED,THEPROBESMAYA
32、LSOBEPROVIDEDWITHINTEGRALFUSESTOPROTECTTHEMEASURINGCIRCUITOFTHEINSTRUMENTANDFACILITATESAFEUSEOFTHEVOLTMETERADDITIONALLY,THEPROBESCOULDALSOINCLUDEINTEGRALHIGHVOLTAGERESISTORSWHICHWILLPREVENTELECTRICALOVERLOADORABUSEOFTHEVOLTMETERDUETOVOLTAGETRANSIENTSTHEFUNCTIONOFTHEVOLTAGEMEASURINGAPPARATUSISBROADLY
33、ILLUSTRATEDINTHEBLOCKDIAGRAMOFFIG2,WHEREINANINPUTVOLTAGEWILLBECONNECTEDTHROUGHTERMINAL30TOASIGNALCONDITIONINGCIRCUIT32THESIGNALCONDITIONINGCIRCUIT32PROVIDESADDITIONALPROTECTIONAGAINSTACCIDENTALOVERLOADSANDFILTERSANDATTENUATESTHEINPUTSIGNALWHILEPERFORMINGPROCESSINGTHEREOFTHEOUTPUTOFTHESIGNALCONDITION
34、INGCIRCUIT32ISCOUPLEDTOANVAC/VDCCONTROLCIRCUIT34DESIGNEDTOTESTTHEINPUTSIGNALTODETERMINEWHETHERTHESIGNALISANACORDCSIGNALORACOMBINATIONTHEREOFTHECONTROLCIRCUIT34WILLAUTOMATICALLYSELECTTHEPROPERTYPEOFVOLTAGESIGNALTOACCURATELYMEASURETHEMAGNITUDETHEREOFWHENBOTHACANDDCINPUTVOLTAGESAREPRESENT,THEVACFUNCTIO
35、NISAUTOMATICALLYSELECTEDIFPEAKACVOLTAGEISGREATERTHANTHEMAGNITUDEOFDCVOLTAGEPRESENTIFTHEPEAKACVOLTAGEISLESSTHANTHEMAGNITUDEOFDCVOLTAGE,THEVDCFUNCTIONWILLBEAUTOMATICALLYSELECTED,SUCHTHATTHEUSERWILLALWAYSBEPROVIDEDWITHANINDICATIONOFTHEHIGHESTVOLTAGEPRESENTONTHETESTCIRCUITONCETHEDETERMINATIONOFWHETHERAN
36、ACORDCINPUTVOLTAGEHASBEENMADE,APROPERREFERENCEVOLTAGEWILLBEAUTOMATICALLYSELECTEDFORTHECURRENTTYPEOFVOLTAGEBEINGMEASUREDWITHREFERENCETOFIGS3AAND3B,THEMEASURINGCIRCUITOFTHISEMBODIMENTWILLBEDESCRIBEDINMOREDETAILASSEENINFIG3A,THEMEASURINGINSTRUMENTISPROVIDEDWITHEXTERNALPOSITIVEANDNEGATIVEPROBESWHICHINCL
37、UDEINTERNALHIGHVOLTAGERESISTANCESRLANDR2THEHIGHVOLTAGERESISTANCESR1ANDR2ACTTOPROTECTTHEINTERNALCIRCUITSOFTHEVOLTMETERFROMVOLTAGETRANSIENTSANINPUTVOLTAGEISCONNECTEDTOTERMINALS50FORMEASUREMENT,ANDTHEINPUTVOLTAGEISPASSEDONTOASIGNALCONDITIONINGCIRCUITWHICHMAYINCLUDEANOTHERHIGHVOLTAGERESISTANCER3FORADDIT
38、IONALPROTECTIONTURNINGNOWTOFIG4,THEREISGENERALLYILLUSTRATEINBLOCKFORM,ACIRCUITDIAGRAMOFANALTERNATEEMBODIMENTOFTHEMEASURINGCIRCUITASSOCIATEDWITHTHEVOLTAGEMEASURINGAPPARATUSOFTHEINVENTIONANINPUTVOLTAGEWILLBECONNECTEDTHROUGHTERMINAL2，BEINGTHEINPUTPROBESOFTHEVOLTMETERASIGNALCONDITIONINGCIRCUIT202WHICHIS
39、SIMILARTOTHATPREVIOUSLYDESCRIBED,BUTWHICHALSOINCLUDESADDITIONALCIRCUITRYISINCLUDEDTHISSIGNALCONDITIONINGCIRCUIT202AGAINISADAPTEDTOPROVIDEPROTECTIONAGAINSTACCIDENTALOVERLOADSANDPROCESSESTHEINPUTSIGNALTOPROVIDEASCALEDANDATTENUATEDSIGNALWHICHCANBEPASSEDONFORFURTHERPROCESSINGWITHINTHEINSTRUMENTTHESIGNAL
40、CONDITIONINGCIRCUIT202SIMULATESALOWIMPEDANCEMETERANDALLOWSTHEEFFECTSOFDISTRIBUTEDCAPACITANCEWITHINATESTCIRCUITTOBESUBSTANTIALLYELIMINATEDTURNINGNOWTOFIGS5AAND5B,THEMEASURINGCIRCUITOFTHISEMBODIMENTOFTHEINVENTIONWILLBEDESCRIBEDINMOREDETAILASSEENINFIG5A,THEMEASURINGINSTRUMENTISPROVIDEDWITHEXTERNALPOSIT
41、IVEANDNEGATIVEPROBES220,WHICHMAYINCLUDEINTERNALFUSES222ASSOCIATEDTHEREWITHTHEINTERNALFUSES222WILLPROVIDE“BACKUP“PROTECTIONFORTHEINTERNALCIRCUITSOFTHEMEASURINGDEVICEINTHISEMBODIMENT,THEHIGHVOLTAGERESISTORSUSEDINTHETESTPROBESTOPROTECTAGAINSTHIGHVOLTAGETRANSIENTSHAVEBEENELIMINATEDANDPROTECTIONAGAINSTHI
42、GHVOLTAGETRANSIENTSISNOWPERFORMEDBYPOWERRESISTORSR30ANDR31PRIMARILY,WHICHARESTRAPPEDACROSSTHEINPUTPROBES222ANUMBEROFPOSITIVETEMPERATURECOEFFICIENTPTCTHERMISTORS224AREALSOPROVIDEDINASSOCIATIONWITHPOWERRESISTORSR30ANDR31ASSHOWNINFIG5A,TWOPTCTHERMISTORSARECONNECTEDINSERIESANDAREPLACEDINPARALLELWITHANOT
43、HERTWOSERIESCONNECTEDPTCTHERMISTORSINTHEPRESENTINVENTION,THEDIGITALVOLTMETERSIMULATORALOWIMPEDANCETYPEMETER,ANDTHEPOWERRESISTORR30ANDPTCTHERMISTORS224PROVIDEASHUNTINGIMPEDANCEACROSSTHEINPUTTERMINALSOFTHEMETERWHICHDIVERTSMOSTOFTHEPARASITICCURRENTINDUCEDBYDISTRIBUTEDCAPACITANCEINTHESYSTEMINTHISWAY,WHE
44、REACONVENTIONALDIGITALVOLTMETERORDIGITALMULITIMETERWILLREADBETWEEN5090VOLTSDUETODISTRIBUTEDCAPACITANCE,THEMEASURINGINSTRUMENTOFTHEINVENTIONWOULDINDICATEONEVOLTORLESS,SUCHTHATACCURATEVOLTAGEREADINGSCANSTILLBEMADEWITHTHEINSTRUMENTINTHEMETERINGCIRCUIT,THEINPUTVOLTAGEISCONNECTEDTOTHEINVERTINGINPUTOFSIGN
45、ALCONDITIONINGOPAMP226THROUGHAVOLTAGEDIVIDERCOMPRISINGRESISTANCESR31ANDR32,WHICHPROVIDEVOLTAGESONLINES228AND230TOYIELDVOLTAGESIGNALSINDICATIVEOFADCINPUTVOLTAGETOTHEINSTRUMENTTHEVOLTAGESIGNALFROMTHEVOLTAGEDIVIDERNODEDIRECTLYFOLLOWINGRESISTANCER31ALONGLINE228ISCOUPLEDTOASWITCH240AFTERADDITIONALCONDITI
46、ONINGANDFILTERINGPROVIDEDBYRESISTORR56ANDCAPACITORC16ANOTHERVOLTAGESIGNALISEXTRACTEDFROMTHEVOLTAGEDIVIDERAFTERRESISTANCER32,WHICHISCONNECTEDTOSWITCH240ALONGLINE2THESEINPUTSTOSWITCH240WILLPRODUCEOUTPUTSONLINES310AND312TOTHEINHIANDINLOOFTHEADCONVERTER275BOTHOFTHEDCSELECTIONSIGNALSONLINES228AND230WHICH
47、ARECONDITIONEDBYTHEVOLTAGEDIVIDERCOMPRISINGRESISTANCESR31ANDR32WILLINCLUDEINPUTOFFSETVOLTAGESFROMTHEDIVIDERNODESUPONDIFFERENTIALMEASUREMENTINTHEADCONVERTER275,THEDCINHIANDINLOVOLTAGESWILLCANCELTHEOFFSETVOLTAGESASSOCIATEDTHEREWITHSOASTOBESELFCORRECTINGFORANACCURATEINDICATIONOFTHEVOLTAGEAMPLITUDE译文题目数
48、字电压表发明背景本发明一般涉及到电压测量设备，尤其是能提供一个安全的能自动选择正确测量交流电压和测量直流电压功能的测量仪器。本发明的数字电压表受电容分布的影响较少，其准确性和可信性能够得到保证。很多情况下，从检查和测试用电服务设施，到检查住宅供电线路的完整性，就要求电压测量设备能够测量交流电压，直流电压或两者兼而有之的大小。明显的是在验证电压电器服务的时候，可能会遇到非常高的电压，这样使一些常规的功率测量也变成了危险的活动。为了提供这种测量能力，已经制定了AC/DC电压读取电压表或一些复合功能的仪表以适应联系其它电压参数去测量电压的方式。在这方面，各种交流和直流模拟电压表已经开发出来并配合使用
49、一种电磁表以此指示被测量的电压幅度。因为它们具有较低的输入电阻，所以这些模拟式仪器需要大量的电流才能使指标偏转，这就是它们的不足之处，这将在许多情况下误报电压测量的数据。数字电压表被开发用于避免一些模拟仪表的不准确性，但相反也有一些其它被公认的不足之处。模拟和数字电压表都受到不准确，太笨重，易碎等有可能的危险性。许多这样的仪器的范围和功能的选择是由用户决定的。而电压表必须是在一个数量级的测量范围内使用，这就要求用户具有预期判断电压大概值的能力。如果在一个电压表上选定一个错误的功能或范围，有可能出现测量仪器的爆炸。电工或其它用户当遇到其它问题时，都会试图使用一个交流电压表有明确规定的，是否有一个
50、特定的交流或直流电压波纹的测量，或带有交流纹波直流电压的测量。在其它情况下，如检查住宅供电线路的完整性，这个测量电压的路线之间的连接和复合开关都在开口位置被执行。在这些和其它情况下，分布电容的存在可能影响电压表的准确测量。大多数数字电压表以及一些模拟电压表不能在电容效应中明显的存在。一个“寄生电容”它具有通过它返回到地面的分布式自由空间和内部导线布线电容的负载电流。虽然敏感的电压表可以测量这种“寄生”电流，但该电流的存在将得到由于负载的接线状态而模棱两可的读数。低阻抗电压表可避免分布电容的影响。在一定程度上，这些先前提及关于的电压测量精度还有不足之处。在另一些情况下，电气连续性测量期望被制成一
