XITRON XT2640 - Watts, Var And Va Measurement Specifications

XT2640OperatingManual 13July2016 Page174of187
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TotalHarmonicAmplitudeErrors=±0.0006%ofreading
Example3
ForanADtypechannelthemaximumerrorofameasurementofa10%THDofa5Armscurrentat50Hzwhen50harmonicsare
configuredisaworstcaseof±0.13%ascalculatedby:
(0.005+0.000025*N)*%THD=(0.005+(0.000025*50))*10=0.0625%THD
0.00005*N*√N=0.00005*50*√50=0.0177%THD
0.015+0.15/A
AC
=0.015+0.15/5=0.045%THD
Example4
ForanAtypechannelthemaximumerrorofthecurrent:voltagefundamentalphaseat50Hzisaworstcaseof0.005°+0.015°*0.05=
±0.006°
Example5
ForanADtypechannelthemaximumerrorofthecrestfactorofa5A/50Hzvoltageisaworstcaseof5mA/5A=0to+0.001(i.e.
biasedtoahigherreading)
28.4 WATTS, VARANDVAMEASUREMENTSPECIFICATIONS
ThechartsbelowshowguaranteedmaximumWattserrorsforDC,MAINS,AVIONICS,and50kHzfrom100µWuptothehighest
availableusingaDoptioncurrentmeasurement(HandXoptioncurrentaccuraciesaresimilarwithintheirrespectiverangeof
currentsandarenotshownforclarity),expressedas%ofWattsreadingandarevalidwithin±5Cofthecalibrationtemperature
(add0.005%perCbeyondthis)andwherenosignificantcommon‐modeispresent.Followingthechartsisatablewhichcanbe
usedtocalculatetheguaranteedaccuraciesforapplicationsotherthanshowninthechartsandalsoforthecomputationof
numericalerrors.
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0.01%
0.10%
1.00%
10.00%
0.0001 0.001 0.01 0.1 1 10 100 1000Watts
WattsErrorvsWattsat3.3Vand200VDC
AD@200V
SD@200V
WD@200V
LD@3.3V
AD@3.3V
SD@3.3V
WD@3.3V
0.01%
0.10%
1.00%
10.00%
0.0001 0.001 0.01 0.1 1 10 100 1000Watts
WattsErrorvsWattsat115Vand240VMAINSorAVIONICS(PF=1)
AD@240V
SD@240V
WD@240V
AD@115V
SD@115V
WD@115V
0.01%
0.10%
1.00%
10.00%
0.0001 0.001 0.01 0.1 1 10 100 1000Watts
WattsErrorvsWattsat115Vand240V50kHz(PF=1)
AD@240V
SD@240V
WD@240V
AD@115V
SD@115V
WD@115V
SDandWDplotsareindistinguishable
Add0.005%toAD
p
lotsforAVIONICS