XITRON XT2640 - Calibration Adjustment; Equipment Required

XT2640OperatingManual 13July2016 Page183of187
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31 CALIBRATIONADJUSTMENT
Typicallycalibrationadjustmentshouldberarelyneeded;howeveryoumaywishtoperformitatperiodicintervalstoensure
optimalperformance.
 TheXT2640employsinternalsoftwarecalibrationadjustments,therearenophysicaladjustmentsrequired.Theseadjustments
areneededtocorrectformanufacturingtolerancesinthecomponentsusedintheXT2640.
 Itisimportanttonotethatthereisnocalibrationofelectro‐mechanicalperformance(e.g.highfrequencyresponse)ordesign
defects,givingyouahighdegreeofcertaintythattheXT2640maintainsits’specifications.
 CalibrationadjustmentcanonlybeperformedviaaninterfaceusinganapplicationprovidedontheCDwiththeXT2640.This
applicationdoesnotcontrolthesourceofthevoltageorcurrentbeingusedforadjustment,itonlycontrolstheXT2640.You
shouldensure‐
o Thecomputerbeingusedhasasuitableinterfaceinstalled.
o ThecomputerbeingusedhasthesuppliedXT2640calibrationadjustmentapplicationinstalled.
o TheXT2640hasbeenproperlyconfiguredfortheinterfacechosen.
 CalibrationadjustmentshouldonlybeperformedaftertheXT2640hasbeencontinuouslypoweredinastableenvironmentfor
atleast1hour.IftheXT2640hasbeenmovedbetweendifferingenvironments,thenatleast3hoursshouldbeallowed.
 Intheprocedurebelow,eachinstalledchanneliscalibratedseparatelyandtheprocedurevariesautomaticallydependingonthe
channeltype(the1
st
letterofthechannelcode)andthechannelcurrentoption(the2
nd
letterofthechannelcode).
 ThesuppliedapplicationautomaticallysavesthemeasurementconfigurationoftheXT2640priortoreconfiguringitfor
calibrationadjustmentsandrestoresthesavedconfigurationaftercalibrationadjustmenthasbeencompleted.
 TheXT2640maybeadjustedatanyfrequencybetween45and450Hz.Itnormallyproducestheoptimumresultstocalibrate
theXT2640at50,55or60Hz.Atthesefrequenciesthespecificationsofthesourcearetypicallythemostaccurate.When
calibratingatverylowsignallevelsyoumayexperienceinterferencefromthelocalmainssupply,inthesecasesitis
recommendedtoadjusttheXT2640atafrequencyofotherthanthelocalmainssupply.TheaccuracydifferenceintheXT2640
between50,55or60Hzisextremelysmallandmaybeignored,andthedifferencebetweenperformingtheadjustmentsatnear
mainsfrequencyvs.400HzforaerospaceapplicationsmayalsobedisregardedasthedifferenceintheXT2640accuracyis
negligibleattheadjustmentlevels.
31.1 EQUIPMENTREQUIRED
Thefollowingequipmentwillberequiredduringcalibrationadjustment‐
1.
AshortcircuitcapableofbeingattachedbetweentheVorAterminalsoftheXT2640channels(standard4mmbananaterminals
using¾inchspacing)andamethodofgroundingtheshortcircuit.Thisshortcircuitshouldbeconstructedtominimize
thermallyinducedEMFs.
2.
(OnlyrequiredforW,SandAchanneltypes)AsourceofACvoltagesintoa1.2Mohmload(SorAchanneltypes)or400Kohm
load(Wchanneltypes)of10V,20V,and200Vrmsatafrequencyofbetween45and450Hz(theuseof50Hzor60Hzis
recommended)withsufficientamplitudeaccuracytoensurethedesiredratiobetweenthespecifiedXT2640accuracyandthat
oftheappliedvoltage.Fora4:1TUR(typicallyused)thevoltagesourceshouldhaveanaccuracyof<0.025%+0.75mV(SorW
channeltypes)or<0.0075%+0.5mV(Achanneltypes)attheselevels.
3.
(OnlyrequiredforLchanneltypes)AsourceofACvoltagesintoa120kohmloadof1V,2V,and20Vrmsatafrequencyof
between45and450Hz(theuseof50Hzor60Hzisrecommended)withsufficientamplitudeaccuracytoensurethedesired
ratiobetweenthespecifiedXT2640accuracyandthatoftheappliedvoltage.Fora4:1TUR(typicallyused)thevoltagesource
shouldhaveanaccuracyof<0.0075%+50uVattheselevels.
4.
(OnlyrequiredforchannelshavingtheHcurrentoption)AsourceofACcurrentintoa0.01ohmload(plustheimpedanceofthe
wiringbetweentheXT2640andthesource)at1A,2Aand10Armsatafrequencyofbetween45and450Hz(theuseof50Hzor
60Hzisrecommended)withsufficientamplitudeaccuracytoensurethedesiredratiobetweenthespecifiedXT2640accuracy
andthatoftheappliedcurrent.Fora4:1TUR(typicallyused)thecurrentsourceshouldhaveanaccuracyof<0.025%+200uA
(SorWchanneltypes)or<0.0075%+125uA(Achanneltypes)attheselevels.
5.
(OnlyrequiredforchannelshavingtheDcurrentoption)AsourceofACcurrentintoa0.02ohmload(plustheimpedanceofthe
wiringbetweentheXT2640andthesource)at1A,2Aand10Armsatafrequencyofbetween45and450Hz(theuseof50Hzor
60Hzisrecommended)withsufficientamplitudeaccuracytoensurethedesiredratiobetweenthespecifiedXT2640accuracy
andthatoftheappliedcurrent.Fora4:1TUR(typicallyused)thecurrentsourceshouldhaveanaccuracyof<0.025%+125uA
(SorWchanneltypes)or<0.0075%+75uA(Achanneltypes)attheselevels.
6.
(OnlyrequiredforchannelshavingtheDcurrentoption)AsourceofACcurrentintoa0.57ohmload(plustheimpedanceofthe
wiringbetweentheXT2640andthesource)at100mArmsatafrequencyofbetween45and450Hz(theuseof50Hzor60Hzis
recommended)withsufficientamplitudeaccuracytoensurethedesiredratiobetweenthespecifiedXT2640accuracyandthat
oftheappliedcurrent.Fora4:1TUR(typicallyused)thecurrentsourceshouldhaveanaccuracyof<0.02575%(SorWchannel
types)or<0.007875%(Achanneltypes)attheselevels.
7.
(OnlyrequiredforchannelshavingtheXcurrentoption)AsourceofACvoltageintoa20.5Kohmloadat0.1V,0.5V,2Vand
10Vrmsatafrequencyofbetween45and450Hz(theuseof50Hzor60Hzisrecommended)withsufficientamplitudeaccuracy
toensurethedesiredratiobetweenthespecifiedXT2640accuracyandthatoftheappliedvoltage.Fora4:1TUR(typically
used)thevoltagesourceshouldhaveanaccuracyof<0.025%+12.5uV(SorWchanneltypes)or<0.0075%+7.5uV(Achannel
types)attheselevels.Notethatsomesourcesmayrequirethatyouadjustthevoltagesettingtoachievethecorrectvoltageinto
a20.5Kohmload.