XITRON XT2640 - Page 81

XT2640OperatingManual 13July2016 Page81of187
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 TheFUNDsettingoftheDCVPAshouldbesettotheVPAmeasuringthePWMGenerator.
 TheHARMONICSsettingfortheDCVPAshouldbesetto0(itcanalsobesettoanon‐zerovalue,inwhichcasethe
ripplecontentoftheDCsupplywillbeavailableasharmonics).
 UsethesameLF/PERIODandRESPONSEsettingsinbothVPAs.
InthismannerthetwoVPAmeasurementswillbecloselysynchronizedbyalwaysstartingthematthesametimeso
efficiencywilltrackfastchangestosignals.Bothmeasurementperiodswillbealmostthesame,sosynchronizationwillbe
verycloseandmeasurementswillbealmostcontinuousasanypausesbetweenmeasurementswillbeveryshort(typically
afewtensofµsec).
3.
Iftherewillbesignificantchangestothelevelsorsignalswhichrequiretrackingforefficiencyresultsandthesupplyis
eitherDCcontainingrippleatsomefrequencyotherthanthemodulationfrequency,oritisanACsupply(e.g.mains).
 TheMEASMODEshouldbesettoSYNCVPA.
 BothsetsofmeasurementsshouldbeconfiguredinseparateVPAs.AnyVPAcanbeusedforeithermeasurementand
bothareindependentlyconfigured.Itisrecommendedthat,ifpossible,bothLF/PERIODsettingsbethesamevalue.
 UsethesameRESPONSEsettinginbothVPAs.
InthismannerthetwoVPAmeasurementswillbecloselysynchronizedbyalwaysstartingthematthesametime,even
thoughtheymightnotactuallyendatexactlythesametime,soefficiencywilltrackfastchangestosignalsasmuchas
possiblebuttheremaybeaslightdifferencebetweenthetwomeasurementperiodsandneithermeasurementwillbe
continuousaseachmustwaitfortheothertofinishbeforeitcanrestart.
4.
Ifnoneoftheabovesituationsaretrue,orifyouareuncertainifanyoftheabovesituationsaretrue.
 TheMEASMODEshouldbesettoMULTIVPA.
 BothsetsofmeasurementsshouldbeconfiguredinseparateVPAs.AnyVPAcanbeusedforeithermeasurementand
botharecompletelyindependentlyconfigured.
 Althoughthetwomeasurementperiodswillbeasynchronousyoucanreduceanyabnormalefficiencyresultsduring
fastchangesasfollows–
o UsethesameLF/PERIODsettinginbothVPAsifpossible.
o UsetheshortestpossiblemeasurementperiodintheLF/PERIODsettingsofbothVPAs.
o UsethesameRESPONSEsettinginbothVPAs.
InthismannerthetwoVPAmeasurementswillbenotbesynchronizedinanymanner,soefficiencymaynotcorrectlytrack
fastchangestosignalsbutwillbeaccuratewhilebothmeasurementsarestable.Inthisoptionbothmeasurementsare
alwayscontinuous.Notethatyoucanreadilychangetooption#3abovebysimplychangingtheMEASMODEtoSYNCVPA.
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