XITRON XT2640 - Performing Startup or Inrush Measurements; Obtaining a Graphical and Numerical Inrush Current Measurement

XT2640OperatingManual 13July2016 Page71of187
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14 PERFORMINGSTARTUPORINRUSHMEASUREMENTS
TheXT2640providesseveralmethodsforperformingmeasurementsofInrushorfordevicestartup.Whichmethodischosenisup
toyou,aseachhasitsmerits.
ItisassumedinthissectionthatyouareconversantwiththegeneraloperatingmethodsusedintheXT2640asdescribedinsection
12.
ThissectionisspecificallywrittentodescribetwosuchmethodsformeasuringInrushcurrents;howeveritmayequallybeapplied
forotherdevicestartupmeasurements.
Usuallythemeasurementconfigurationsuitableforinrushmeasurementisnotthesameasthatusedfor‘normal’power
measurements.Thisoftenresultsinerrorsbeingmadeineithertheinrushmeasurementorinnormalpowermeasurements
becausetheseconfigurationchangesareforgottenorimproperlymade.
Inrushmeasurementsareusuallyperformedwithnobandwidthrestrictionswhereasnormalpowermeasurementsmay
havearestrictedbandwidth.
InrushmeasurementstypicallyneedtobeperformedontheHIrangeofanyDcurrentoptionchannels,whereasnormal
powermeasurementsusethemostoptimalrangeofcurrentmeasurementforthenormalcurrentlevelsofadevice.
14.1 OBTAININGAGRAPHICALANDNUMERICALINRUSHCURRENT
MEASUREMENT
ThisfirstmethoddescribedrequiresnospecificconfigurationchangestotheMEASCONFIGscreentoperformaninrush
measurementasanychangesrequiredwillbeautomaticallyapplied.
Thishastheadvantageofbeinganeasilyrepeatablemeasurement;themeasurementisnotdependentonrememberingtore‐
configureforinrushmeasurements(andrememberingtoreversethatlater),andtheconfigurationoftheSCOPEcantypicallybeleft
atthesettingsfortheinrushmeasurementsotheydonotneedtobechangedandalsononeofthesesettingshaveanysignificant
impactontheinrushmeasurementitself,onlyhowitisdisplayed.
ForfulldetailsregardingusingtheSCOPEscreenseesection12.10.
TheexamplescreenbelowshowsanexampleSCOPEscreenusedforthispurpose,showinganinrushcurrentmeasurementhaving
beenperformed.InthiscasevoltagewascontinuouslyappliedtotheXT2640terminals;thepowerswitchofthedevicebeingtested
wasusedtoapplythepowerinrush.Thiscanalsobeachievedbyturningonandoffthesourceofthevoltage.
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1. Turnoffthedevicebeingtested.ItdoesnotmatterifthevoltageisswitchedoffbetweentheXT2640andthedevice(sothe
voltageisalwayspresentattheXT2640)oratthesupplytothedevice+XT2640(sothevoltageisnotinitiallypresentatthe
XT2640).Typicallyadeviceshouldhavepowerremovedforsomeperiodoftimebeforere‐applyingpowerforaninrush
measurement(oftenseveralminutes).
2. ConfiguretheXT2640Scopecapturefortheinrushmeasurementasshownintheexamplescreenbelow–