Performanceindicatorsofdetectioninstruments檢測儀表的性能指標落版在此檢測儀表的性能指標Performanceindicatorsofdetectioninstruments謝聰XieCong主講教師Teacher生產(chǎn)的方向Productiondirection精準的數(shù)據(jù)Accuratedata檢測儀表的性能指標Performanceindicatorsofdetectioninstruments檢測儀表就是獲得參數(shù)量化數(shù)據(jù)并進行顯示、標準化轉(zhuǎn)換和遠距離傳輸?shù)墓ぞ?。Detectioninstrumentisatooltoobtainquantifiedparameterdataanddisplay,standardizeconversionandlong-distancetransmission.檢測儀表Detectioninstruments實現(xiàn)這些精準數(shù)據(jù)獲取的關(guān)鍵：Thekeytoachievingtheseaccuratedataacquisition：檢測儀表的性能指標Performanceindicatorsofdetectioninstruments測量指示儀表Measurementindicatinginstruments測量變送器MeasurementtransmitterCaseimport案例導入在某化工企業(yè)的生產(chǎn)車間，原本用于監(jiān)測反應釜溫度的檢測儀表頻頻出現(xiàn)偏差。起初只是小小的數(shù)值波動，沒引起足夠重視，可后來偏差越來越大，導致反應溫度失控，最終引發(fā)了一場生產(chǎn)事故。Intheproductionworkshopofachemicalcompany,thedetectioninstrumentoriginallyusedtomonitorthetemperatureofthereactorfrequentlydeviated,atfirstitwasjustasmallnumericalfluctuation,sufficientattentionwasnotpaid.Butthenthedeviationbecamebiggerandbigger,causingthereactiontemperaturetogetoutofcontrol,eventuallytriggeredaproductionaccident.Caseimport案例導入Caseimport案例導入檢測儀表的性能指標PerformanceindicatorsofdetectioninstrumentsPerformanceindicatorsofdetectioninstruments檢測儀表的性能指標Performanceindicatorsofdetectioninstruments檢測儀表的性能指標檢測儀表的指示值X與被測量真值Xz之間的差值：Δ=X?Xz

ThedifferenceΔ=X?XzbetweentheindicatedvalueXofthedetectioninstrumentandthemeasuredtruevalueXz.絕對誤差Absoluteerror由于真值無法獲取，實際計算時用精確度高的標準表測得的標準值

X?代替真值

Xz，此時絕對誤差Δ=X?X?.Sincethetruevaluecannotbeobtained,useastandardinstrumentwithhighaccuracyinactualcalculationthemeasuredstandardvalueX?

replacesthetruevalueXz,atthistime,theabsoluteerrorΔ=X?X?.儀表在其標尺范圍內(nèi)各點讀數(shù)的絕對誤差中絕對值最大的絕對誤差稱為最大絕對誤差Δmax。TheabsoluteerrorwiththelargestabsolutevalueamongtheabsoluteerrorsofeachpointreadingoftheinstrumentwithinitsscalerangeiscalledthemaximumabsoluteerrorΔmax.

Performanceindicatorsofdetectioninstruments檢測儀表的性能指標基本誤差又稱引用誤差或相對百分誤差，是一種簡化的相對誤差。Basicerror,alsoknownascitationerrororrelativepercentageerror,isasimplifiedrelativeerror.基本誤差Basicerror基本誤差表示儀表在規(guī)定工作條件下測量時，允許出現(xiàn)的最大誤差限。Thebasicerrorrepresentsthemaximumerrorlimitallowedbytheinstrumentwhenmeasuringunderspecifiedoperatingconditions.若儀表使用條件超出規(guī)定范圍，如溫濕度超限或電源質(zhì)量不滿足要求等引起的額外誤差則稱為附加誤差。Iftheinstrumentoperatingconditionsexceedthespecifiedrange,suchasadditionalerrorscausedbytemperatureandhumidityexceedingthelimitorpowerqualitynotmeetingtherequirements,itiscalledadditionalerrors.Basicerror??Performanceindicatorsofdetectioninstruments檢測儀表的性能指標模擬儀表的精確度用基本誤差來表示。儀表工業(yè)規(guī)定將基本誤差去掉“±”號及“%”號后稱為儀表精度，它體現(xiàn)了在規(guī)定工作條件下測量結(jié)果與實際值的接近程度。Theaccuracyofanaloginstrumentsisexpressedbybasicerror.Theinstrumentindustrystipulatesthatthebasicerroriscalledinstrumentaccuracyafterremovingthe"±"and"%"signs,whichreflectstheproximitybetweenthemeasurementresultsandtheactualvaluesunderspecifiedworkingconditions.精度Accuracy國家規(guī)定了儀表的精確度（精度）級系列，如0.05、0.1、0.2

等，精度等級數(shù)值越小，儀表精確度越高。ItstipulatestheaccuracylevelseriesofinstrumentsinChina,suchas0.05,0.1,0.2,thesmallertheaccuracylevelvalue,thehighertheaccuracyoftheinstrument.符號標注在儀表面板SymbolsaremarkedoninstrumentpanelPerformanceindicatorsofdetectioninstruments檢測儀表的性能指標【例1】已知該測溫儀表測溫范圍為-100~500℃，全量程內(nèi)最大絕對誤差為+7.8℃，請試著確定該儀表的精度等級。[Example1]Itisknownthatthetemperaturemeasuringrangeofthetemperaturemeasuringinstrumentis-100-500℃,themaximumabsoluteerrorinthefullrangeis+7.8°C,pleasetrytodeterminetheaccuracyleveloftheinstrument.解：首先計算基本誤差：Solution:First,thebasicerroriscalculated:1.3儀表精度等級中沒有1.3級，且該儀表誤差超過1.0級儀表允許的最大絕對誤差，所以確定這臺測溫儀表精度等級為1.5級。Thereisnolevel1.3accuracylevelfortheinstrumentsandtheinstrumenterrorexceedsthemaximumabsoluteerrorallowedbylevel1.0instrument,therefore,itisdeterminedthattheaccuracylevelofthistemperaturemeasuringinstrumentis1.5.Performanceindicatorsofdetectioninstruments檢測儀表的性能指標【例2】已知測壓儀表測壓范圍為0~12MPa，工藝要求測壓示值誤差不超過±0.055MPa，應如何選擇儀表精度等級才能滿足以上要求？[Example2]Itisknownthatthepressuremeasuringrangeofthepressuremeasuringinstrumentis0~12MPa,theprocessrequiresthattheerrorofpressuremeasurementindicationvalueshouldnotexceed±0.055MPa.Howshouldtheinstrumentaccuracylevelbeselectedtomeettheaboverequirements?解：根據(jù)公式計算出儀表的允許基本誤差：Solution:accordingtotheformula,theallowablebasicerroroftheinstrumentiscalculated:0.458由于選擇0.5級儀表時，允許的最大絕對誤差±0.06MPa超過工藝允許數(shù)值，所以應選擇精度等級為0.4級的儀表。Becausewhenselecting0.5levelinstrument,themaximumallowableabsoluteerror±0.06MPaexceedstheallowablevalueoftheprocess,aninstrumentwithanaccuracylevelof0.4shouldbeselected.Performanceindicatorsofdetectioninstruments檢測儀表的性能指標靈敏度S表示儀表對被測參數(shù)變化的敏感程度，用儀表在x處輸出變化Δy與輸入激勵變化量Δx的比值表示，它是儀表輸入/輸出特性曲線在該檢測點的斜率。SensitivitySrepresentsthesensitivityoftheinstrumenttochangesinmeasuredparameters,whichisexpressedastheratiooftheoutputchangeΔyoftheinstrumentatxtotheinputexcitationchangeΔx,itistheslopeofthemeterinput/outputcharacteristiccurveatthisdetectionpoint.靈敏度與靈敏限Sensitivityandsensitivitylimit當特性曲線為線性時，靈敏度為常數(shù)；當儀表不完全線性時，k表示平均靈敏度。Whenthecharacteristiccurveislinear,thesensitivityisconstant;Whentheinstrumentisnotperfectlylinear,krepresentstheaveragesensitivity.Performanceindicatorsofdetectioninstruments檢測儀表的性能指標靈敏限指指針式儀表在量程起點處，能引起指針動作的最小被測參數(shù)值，小于此值指針不動作，也叫儀表死區(qū)。Theminimummeasuredparametervaluethatcancausethepointertomoveatthestartingpointofthemeasuringrangeof

thesensitivepointer-limitinginstrumentislessthanthisvalue,andthepointerdoesnotmove,whichisalsocalledtheinstrumentdeadzone.靈敏度與靈敏限Sensitivityandsensitivitylimit×10℃

0

100

Performanceindicatorsofdetectioninstruments檢測儀表的性能指標對于數(shù)字顯示儀表，常用分辨率和分辨力表示靈敏度和靈敏限。Fordigitaldisplayinstruments,commonlyusedresolutionandresolutionpowerrepresentsensitivityandsensitivitylimit.靈敏度與靈敏限Sensitivityandsensitivitylimit分辨率體現(xiàn)數(shù)字儀表顯示值的精細程度，儀表顯示位數(shù)越多，分辨率越高，例如四位顯示儀表分辨率為千分之一。Theresolutionreflectsthefinenessofthedigitalinstrumentdisplayvalue,themoredigitstheinstrumentdisplays,thehighertheresolution,suchasonethousandthofafour-digitdisplayinstrumentresolution.Performanceindicatorsofdetectioninstruments檢測儀表的性能指標靈敏度與靈敏限Sensitivityandsensitivitylimit對于數(shù)字顯示儀表，常用分辨率和分辨力表示靈敏度和靈敏限。Fordigitaldisplayinstruments,commonlyusedresolutionandresolutionpowerrepresentsensitivityandsensitivitylimit.分辨力指數(shù)顯儀表能夠顯示的最小被測值，比如溫度指示儀最末一位數(shù)字表示的溫度值為0.1℃，則該表分辨力為0.1℃；某數(shù)字電壓表量程0~1.99999V，五位半顯示，最末一位數(shù)字表示電壓值為10μV，其分辨力即為10μV。Resolutionpoweristheminimummeasuredvaluethattheindexdisplayinstrumentcandisplay,forexample,thetemperaturevalueindicatedbythelastdigitofthetemperatureindicatoris0.1°C,thentheresolutionpoweroftheinstrumentis0.1℃;Adigitalvoltmeterhasarangeof0~1.99999V,fiveandahalfdigitsdisplay,thelastdigitindicatesthatthevoltagevalueis10μV,itsresolutionpoweris10μV.Performanceindicatorsofdetectioninstruments檢測儀表的性能指標變差是指在外界條件不變時，用同一儀表對被測量進行往返測量（正行程和反行程），產(chǎn)生的最大差值與測量范圍的比值（用百分比表示）。Variationreferstotheratio(expressedasapercentage)ofthemaximumdifferencetothemeasurementrangegeneratedbytheround-strokemeasurement(forwardstrokeandreversestroke)ofthemeasuredobjectwiththesameinstrumentwhentheexternalconditionsremainunchanged.變差VariationPerformanceindicatorsofdetectioninstruments檢測儀表的性能指標變差Variation造成變差的原因：

Reasonsforvariation:傳動機構(gòu)的間隙

Transmissionclearance運動部件的摩擦

Frictionofmovingparts彈性元件的彈性滯后影響

Elastichysteresiseffectofelasticelements儀表機械傳動部件越少，變差越小。Thefewermechanicaltransmissioncomponentsoftheinstrument,

thesmallerthevariation.變差是指在外界條件不變時，用同一儀表對被測量進行往返測量（正行程和反行程），產(chǎn)生的最大差值與測量范圍的比值（用百分比表示）。Variationreferstotheratio(expressedasapercentage)ofthemaximumdifferencetothemeasurementrangegeneratedbytheround-strokemeasurement(forwardstrokeandreversestroke)ofthemeasuredobjectwiththesameinstrumentwhentheexternalconditionsremainunchanged.Performanceindicatorsofdetectioninstruments檢測儀表的性能指標響應時間是指用儀表檢測被測量時，被測量突然變化后，儀表值經(jīng)過一段時間才能準確顯示被測量，這段時間即為響應時間。Responsetimemeansthatwhenthemeasurandisdetectedbyaninstrument,afterthemeasurandsuddenlychanges,ittakesaperiodoftimefortheinstrumentvaluetoaccuratelydisplaythemeasurand.Thisperiodoftimeistheresponsetime.響應時間Responsetime0

0

它是從被測量階躍變化到檢測儀表指示值穩(wěn)定在新穩(wěn)態(tài)值95%范圍內(nèi)所用的時間。若參數(shù)變化頻繁而儀表響應時間較長，測量結(jié)果會失真。Itisthetimetakenfromthemeasuredstepchangetothetimewhentheindicatedvalueofthedetectioninstrumentstabilizeswithin95%ofthenewsteady-statevalue.Iftheparameterschangefrequentlyandtheinstrumentresponsetimeislong,measurementswillbedistorted.檢測儀表的性能指標Performanceindicatorsofdetectioninstruments準確度高，那就要求其精度等級要滿足要求，不能誤差過大。Iftheaccuracyishigh,thenitsaccuracylevelisrequiredtomeettherequirements.Itserrorcannotbetoolarge.穩(wěn)定性好，數(shù)值不會輕易波動，就要求儀表變差要小。Withgoodstability,

thevaluewillnotfluctuateeasily;Itisrequiredthattheinstrumentshouldbesmallinvariation.響應速度快，能及時反饋溫度變化，就要求其靈敏度要滿足要求。fastinresponsespeed,andcanfeedbacktemperaturechangesintime,itssensitivityisrequiredtomeettherequirements.ResearchQuestions問題研究在食品加工行業(yè)的殺菌環(huán)節(jié)，溫度的精準控制直接關(guān)系到食品安全和產(chǎn)品品質(zhì)。Inthesterilizationprocessofthefoodprocessingindustry,precisetemperaturecontrolisdirectlyrelatedto