XITRON XT2640 - Page 42

XT2640OperatingManual 13July2016 Page42of187
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FortheLFsettingthemeasurementperiodiswidelyvariable;1secondforfrequenciesabove1Hzand1cyclefor
frequenciesbelow1Hz.
FortheVLFsettingthemeasurementperiodiswidelyvariable;5secondsforfrequenciesabove0.2Hzand1cyclefor
frequenciesbelow0.2Hz.
SettingthistoalowernumberedVPAforcesallmeasurementsinbothVPAstobeexactlysynchronous(thisisonly
availableforVPA2or3).ThisconfigurestheVPAbeingconfiguredtousethesameLF/PERIODsettingofthatVPAandalso
usethefundamentalfrequencyofthatVPA.NotethatiftheVPAbeingconfiguredcontainsWtypechannelsthenthelower
numberedVPAselectedheremustalsocontainWtypechannels,andsimilarlyiftheVPAbeingconfigureddoesnotcontain
WtypechannelsthenthelowernumberedVPAselectedheremustalsonotcontainWtypechannels.Ifconfiguredinthis
waytheneachVPAcanstillhaveindependentWIRING,BANDWIDTHandHARMONICSsettingsbutotherwisebehaveasif
configuredinasingleVPA.
Recommendations:
Fortypicalapplications,the10Hz/0.3sor20Hz/0.1ssettingisrecommended.
ForlowpowermeasurementstoEN50564andwitharapidlychangingloadthe45Hz/20mssettingshouldbeconsidered.
Seesection17forfulldetailsregardingEN50564measurements.
12.4.2.2.2 Settingth eSourceoftheFundamentalFrequency
TheFUNDbuttonallowsyoutoselectthesourceoffundamentalfrequencyfortheselectedVPAifMEASMODEisnotEN61000‐3‐2
orEN61000‐3‐12.
IfyouselectNONEthennofundamentalfrequencyisusedandharmonicanalysiswillnotbeavailable.
IfyouselectFIXEDthenafurtherscreenallowsyoutoenterthefrequencytouse.
IfyouselectVOLTAGEorCURRENTthenthefundamentalfrequencywillbemeasuredusingtheselectedsignalsinthis
VPA.Witheitheroftheseselectionsafurtherscreenallowsyoutoenterthemaximumfrequencytomeasure.
IfyouselectMAINSthenthefundamentalfrequencywillbemeasuredusingthevoltagesignalsinthisVPA.Themeasured
frequencymustbeintherange45to65Hz,ifthesignalfrequencycannotbemeasured(orisoutsideofthisrange)thenthe
XT2640mainssupplyfrequencyisused.
IfyouselectAVIONICSthenthefundamentalfrequencywillbemeasuredusingthevoltagesignalsinthisVPA.The
measuredfrequencymustbeintherange300to900Hz.
IfyouselectanotherVPAthenthefundamentalfrequencyusedforthisVPAisautomaticallyobtainedfromthatVPAinreal
time.
IfyouselectaGFUND(1,2or3)thenthefundamentalfrequencyusedforthisVPAisautomaticallyobtainedfromthe
XT2640VPAwhichhasbeenprogrammedtoprovidethatGFUNDmeasurementforthismulti‐unitgroup.
Recommendations:
For50/60HzapplicationstheMAINSsettingshouldbeused.
For400HzapplicationstheAVIONICSsettingshouldbeused.
Whenitisrequiredtomeasuresignalswithafundamentalfrequencyclosetoorabovethemaximummeasurable
frequencyofthechannelsinthisVPAthenselectNONE.
IfmainlytheDCamplitudeisneeded,ornosuitablefundamentalcanbeestablishedfromanysignalandtheACcontentis
primarilyoverafewkHz,theNONEsettingshouldbeused.
WhenitisrequiredtomeasurerippleonaDCsupplyataspecificfrequencyorharmonicsofittheneithertheFIXEDor
MAINSsettingshouldbeused.Forexample,ifmainsrippleistobemeasuredthensetthistoMAINSandsetthe
HARMONICSsettingtoatleast1(typically10ormore),harmonicanalysiswillthenshowthemagnitudeoftherippleat
eachharmonicofmains.
IftheVPAbeingconfiguredismakingDCmeasurementsbutthesignalshavesignificantrippleatafrequencyrelatedto
thatbeingmeasuredbyanotherVPA,thensettingthatotherVPAasthesourceofthefundamentalforthisVPAmaybe
usedtoreducetheeffectsofthatrippleandalsoenablesyoutouseharmonicanalysisintheVPAbeingconfiguredto
measuretheripplecontentoftheDCsignal.
InmostotherapplicationstheVOLTAGEsettingshouldbeselected,howeverifthesignalsareapulsewidthmodulated
waveform(e.g.amotordrive)thentheCURRENTsettingshouldbeselectedasthistypicallyhassignificantlylesscarrier
frequencycontent.Themaximumfrequencyshouldbesetaslowaspossiblebuthighenoughtoallowthefullrangeof
expectedsignalfrequencies.Seesection16forfulldetailsregardingconfiguringmeasurementsonPWMgeneratedsignals.
Note:
Lead/lagandallnon‐harmonicmeasurementsarestillavailablewhennofundamentalcanbemeasured;howeverthe
measurementperiodcannotbeautomaticallyadjustedtobeanintegernumberofcyclesofthesignalACcontent(thishas
minimaleffectifthesignalfrequencyisprimarilyoverafewkHz).
12.4.2.2.3 SettingaHigh FrequencyBandwidthLimit
TheBANDWIDTHbuttonallowsyoutoselectanybandwidthlimitingtousewithintheVPAbeingconfiguredifMEASMODEisnot
EN61000‐3‐2orEN61000‐3‐12.
IfyouselectAUTO‐TRACKthentheXT2640willautomaticallyprovidejustenoughbandwidthlimitationtohavean
insignificanteffectonthemeasurements,asdeterminedfromthefundamentalfrequencyandtheHARMONICSsettingsin
realtime.
IfyouselectUNFILTEREDthereisnobandwidthlimitationandthefullcapabilityofthechannelsisavailable.
IfyouselectUSERyouarealsopromptedtoenterthedesired‐3dBbandwidthlimitation.