XITRON XT2640 - Page 177

XT2640OperatingManual 13July2016 Page177of187

28.4.1.2 HARMONICWATTSMEASUREMENTACCURACYTABLE
Specification
Channel
Type
OptionH OptionDHIRange OptionDLORange OptionXHIRange OptionXLORange
Harmonicor
SpectrumWatts
Error

 All
ACWattsErrors otherthanPhaseFloorError fromprecedin
g
table a
t
levelsandFoftheharmonicorspectrumpoint
+(H/N)
2
*0.5%ofreading
+frombelowusingthefrequencyoftheharmonicorspectrumpoint
<10kHz
AorL
0.006%+(0.004%+0.028%*F)/PF
10k‐115kHz 0.05% +
(
0.004%+0.028%*F
)/
PF
<10kHz
S
0.01%+(0.004%+0.028%*F)/PF
10k‐115kHz 0.05% +
(
0.004%+0.028%*F
)/
PF
<10kHz
W
0.015%+(0.004%+0.013%*F)/PF
10k‐115kHz 0.03%+(0.004%+0.013%*F)/PF
115k‐435kHz 0.08%+(0.004%+0.013%*F)/PF
28.4.1.3 EXAMPLES
Example1
ForanADchannel(HIrange)themaximumerrorofameasurementoftheAC+DCWattsat240Vrms,3Arms,PF=1,50Hzisaworst
caseof±0.051%ofreadingascalculatedby:
ScalingErrors:
BaseScaling=±0.045%
FrequencyDependentScaling=NoneatMAINS
Self‐heatingScaling=±0.05%*(240V/1000)
2
±0.0002%*3
2
=±0.0029%±0.0018%=±0.0047%
TemperatureScaling=nonewithin5Cofthecalibrationtemperature
BandwidthLimitScaling=nonewhenusingAUTO‐TRACK
TotalScalingerrors=±0.0497%ofreading
FloorErrors:
BaseFloor=(240*38µA)+(3*45µV)=9255µW=±9.255mW
DCfloor=0(signalshaveinsignificantDCcontent)
240*3*(1‐cos(cos
‐1
(1)+0.015°*0.05))=720*(1‐cos(0+0.015°*0.05))=720*86pW=62nW(negligible)
TotalFloorErrors=±9.255mW=0.0013%ofreading
Example2
ForanADchannel(HIrange)themaximumerrorofameasurementoftheAC+DCWattsat240Vrms,3Arms,PF=0.5causedbyload
distortion,50Hzisaworstcaseof±0.052%ofreadingascalculatedby:
ScalingErrors:
BaseScaling=±0.045%
FrequencyDependentScaling=NoneatMAINS
Self‐heatingScaling=±0.05%*(240V/1000)
2
±0.0002%*3
2
=±0.0029%±0.0018%=±0.0047%
TemperatureScaling=nonewithin5Cofthecalibrationtemperature
BandwidthLimitScaling=nonewhenusingAUTO‐TRACK
TotalScalingerrors=±0.0497%
FloorErrors:
BaseFloor=(240*38µA)+(3*45µV)=9255µW=±9.255mW
DCfloor=0(signalshaveinsignificantDCcontent)
Note–VA
FUND
is360andPF
FUND
is1becauseofdistortion
360*(1‐cos(cos
‐1
(1)+0.015°*0.05))=360*(1‐cos(0+0.015°*0.05))=360*86pW=31nW(negligible)
TotalFloorErrors=±9.255mW=0.0026%ofreading
Example3
ForanADchannel(HIrange)themaximumerrorofameasurementoftheAC+DCWattsat240Vrms,3Arms,PF=0.5causedbyload
phaseshift,50Hzisaworstcaseof±0.055%ofreadingascalculatedby:
ScalingErrors:
BaseScaling=±0.045%
FrequencyDependentScaling=NoneatMAINS
Self‐heatingScaling=±0.05%*(240V/1000)
2
±0.0002%*3
2
=±0.0029%±0.0018%=±0.0047%
TemperatureScaling=nonewithin5Cofthecalibrationtemperature
BandwidthLimitScaling=nonewhenusingAUTO‐TRACK
TotalScalingerrors=±0.0497%
FloorErrors:
BaseFloor=(240*38µA)+(3*45µV)=9255µW=±9.255mW
DCfloor=0(signalshaveinsignificantDCcontent)
720*(0.5‐cos(cos
‐1
(0.5)+0.015°*0.05))=720*(0.5‐cos(60+0.015°*0.05))=720*11.3µW=8.16mW
TotalFloorErrors=±17.415mW=0.0048%ofreading
