XITRON XT2640 - Obtaining a Numerical Inrush Current Measurement

XT2640OperatingManual 13July2016 Page73of187

ThebuttonintheOFFSETcolumnallowsyoutosetthesignallevelwhichwillcorrespondtothecenterlineofthechart.
Thisonlyaffectshowthetracewillsubsequentlybedisplayedandsocanbechangedafterwards.Forthistypeof
measurementthisistypicallysettozero.
4. PresstheSINGLEbuttontoinitiateaninrushcapture.TheXT2640willnowwaituntilaninrusheventisdetectedbythecurrent
exceedingthetriggerlevelsetabove,asshownbytheSINGLEbuttonlabelchangingtoWAITING.
5. Applypowertothedevice.
6. TheXT2640screenwilldetectthecurrentinrushandcapturethesignalsasshownonthescreen.
Thescreenwillhaveacursorwhichisautomaticallysettothepositionofthemaximuminrushcurrent,andthenumerical
datatotheleftofthechartwillshowthesignalsatthecursorpositionsothetrace1datashowsthemaximuminrush
current.
Youmayre‐scalethetracesverticallytoproperlyshowthemonthescreenifyouwish.Thisisbestaccomplishedby
pressingtheAUTOSCALEbuttonwhichwillautomaticallyadjustthedisplayscalingsothatthetracesoptimallyfitonthe
chart.
YoumayzoomintoshowmoredetailhorizontallysurroundingtheinrusheventbypressingtheZOOMbuttonand
selectingazoomtimebasewhichisfasterthatthetimebaseusedforthecapture.
Youmaymovethecursorbydraggingitacrosschart.PressingtheCURSORbuttonrepositionsthecursoratthemaximum
inrusheventposition.
7. TheabovemayberepeatedasmanytimesasyouwishwithoutrequiringanyactionbyyouotherthanpressingtheSINGLE
buttonandthenre‐applyingpowertothedevice.
8. Anyotherscreenmaybeviewedaftertheinrushcaptureiscompleted,theMEASCONFIGsettingswerere‐activatedandsoall
powermeasurementsareastheyareconfigured.Thisscreenisstillavailablethoughandcanbereturnedtolater.
14.2 OBTAININGANUMERICALINRUSHCURRENTMEASUREMENT
Beforeperformingtheinrushmeasurementinthismanner,youmustensurethatthepresentMEASCONFIGscreensettingsare
compatiblewithperformingsuchameasurement,andthenreplacethe‘normal’powermeasurementconfigurationsettings
afterwards.
TheXT2640mustbeconfiguredtypicallywithaUNFILTEREDsettingforBANDWIDTH,oralternativelywithaspecific
frequencybandwidthlimit.
AllDcurrentoptionchannelswhichwillbeusedforthisinrushcurrentmeasurementshouldbeconfiguredfortheHIA
RANGEselection.
HavingcheckedthattheXT2640iscorrectlyconfigured,youshouldnowpreparetomaketheinrushmeasurement.Theexample
screenbelowshowstheXT2640POWERDATAscreenwhichwillbeusedforthispurpose.

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XT2640+device(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. SelectthePOWERDATAscreenontheXT2640andconfigureittoshowthedesiredchannelorVPA(theleftbuttonacrossthe
topofthescreen)andselecttoshowtheINRUSHdata(themiddlebuttonacrossthetopofthescreen).Thescreenwilllook
similartothatshownintheexampleabove.
3. PresstheCLEARbuttononthisscreen.Thiswillclearanypreviouslymadeinrushmeasurementsandthescreenwillshowthe
highestmeasurementswiththedevicebeingtestedunpowered(soshouldbeverysmallcurrentandpower).Ifaninrush
measurementisbeingrepeatedlymadetoensurethattheworstcasemeasurementismadethenyoucanskipclearingthe
previousresults,inthatcasetheresultsshownwillonlybeupdatedifaninrushmeasurementexceedsthosepreviouslymade.
4. Applypowertothedevice.
a. TheXT2640screenwillbeupdatedtoshowthehighestdatarecordedsinceitwaslastcleared.
b. TheApkandAdataarethemostimportantresultsshownforthistypeoftesting,showingthehighestpeakcurrent
andhighestsinglemeasurementperiodRMScurrentrespectively.Theseprovideyouwiththemeasurementofthe