XT2640 Operating Manual
13 July 2016
Page 173 of 187
28.3.2.2
SECONDARY
CURRENT
MEASUREMENT
ACCURACY
TABLE
Specification
Channel
Type
Option
H
Option
D
HI
Range
Option
D
LO
Range
Option
X
HI
Range
Option
X
LO
Range
Crest
Factor
Error
All
(Total Current Floor Error from preceding table for PK results) / A
AC
Form
Factor
Error
All
(Total Current Floor Error from preceding table for AC+DC results) / A
RECTIFIED
Multi
‐
Channel
Error
For similar
current level and
phase in each
phase.
A
N
(2ø3w)
All
Relevant Current Errors from preceding table for A
øA
+ Relevant Current Errors from preceding table for A
øB
+ 0.0005% of (A
øA
+ A
øB
)*F
A
øC
(3ø3w 2ch)
All
Relevant Current Errors from preceding table for A
øA
+ Relevant Current Errors from preceding table for A
øB
+ 0.0015% of (A
øA
+ A
øB
)*F
A
N
(3ø4w)
All
Relevant Current Errors from preceding table for A
øA
+ Relevant Current Errors from preceding table for A
øB
+ Relevant Current Errors from preceding table for A
øC
+ 0.0015% of (A
øA
+ A
øB
+ A
øC
)*F
Harmonic
or
Spectrum
Error
All
AC Current Errors from preceding table at A and F of the harmonic or spectrum point
+ (H/N)
2
*0.3% of reading
+ (if not fundamental) from below using the frequency of the harmonic or spectrum point
<10kHz
A or L
0.006% of A
AC+DC
10k‐115kHz
0.05% of A
AC+DC
<10kHz
S
0.01% of A
AC+DC
10k‐115kHz
0.05% of A
AC+DC
<10kHz
W
0.015% of A
AC+DC
10k‐115kHz
0.03% of A
AC+DC
115k‐435kHz
0.08% of A
AC+DC
Current
‐
Voltage
Fundamental
Phase
Error
S, A or L
0.005° + 0.015°*F
W
0.005° + 0.007°*F
Harmonic
‐
Fundamental
Phase
Error
(typical,
BANDWIDTH
configured
as
UNFILTERED)
S, A or L
0.02°+0.1°*F+0.001°*H
W
0.02°+0.03°*F+0.001°*H
%THD
Error
Errors shown are
all expressed in
%THD units.
All
(0.005+0.000025*N)*%THD+0.00005*N*√N
+ from below using the frequency of highest included harmonic
<10kHz
A or L
0.015+0.2/A
AC
0.015+0.15/A
AC
0.015+0.001/A
AC
0.015+0.025/A
AC
0.015+0.0006/A
AC
10k‐115kHz
0.15+2/A
AC
0.15+1.5/A
AC
0.15+0.01/A
AC
0.15+0.25/A
AC
0.15+0.006/A
AC
<10kHz
S
0.025+0.2/A
AC
0.025+0.15/A
AC
0.025+0.001/A
AC
0.025+0.025/A
AC
0.025+0.0006/A
AC
10k‐115kHz
0.15+2/A
AC
0.15+1.5/A
AC
0.15+0.01/A
AC
0.15+0.25/A
AC
0.15+0.006/A
AC
<10kHz
W
0.03+0.25/A
AC
0.03+0.18/A
AC
0.03+0.0012/A
AC
0.03+0.03/A
AC
0.03+0.001/A
AC
10k‐115kHz
0.06+2.5/A
AC
0.06+1.8/A
AC
0.06+0.012/A
AC
0.06+0.3/A
AC
0.06+0.01/A
AC
115k‐435kHz
0.15+2.5/A
AC
0.15+1.8/A
AC
0.15+0.012/A
AC
0.15+0.3/A
AC
0.15+0.01/A
AC
28.3.2.3
EXAMPLES
Example
1
For an AD channel (HI range) the maximum error of a measurement of the AC+DC current of a 5Arms signal at 50Hz is a worst case
of ±0.037% of reading as calculated by:
Scaling Errors:
Base Scaling = ±0.03%
Frequency Dependent Scaling = None at MAINS
Self‐heating Scaling = ±0.0002%*5
2
= ±0.005%
Temperature Scaling = none within 5C of the calibration temperature
Bandwidth Limit Scaling = none when using AUTO‐TRACK
Total Scaling errors = ±0.035% of reading
Floor Errors:
AC+DC floor = ±110µA±(1.5µA/5A) at MAINS = ±110.3µA
Common‐Mode = assume connected to 230V mains = 4.6µA at 90° to voltage (so 0 to ±4.6µA depending on current phase)
Total Floor Errors = ±0.1149mA = 0.0023% of reading
Example
2
For an AD channel (HI range) the maximum error of a measurement of the fundamental current of a 5Arms signal at 50Hz when 50
harmonics are configured is a worst case of ±0.038% of reading as calculated by:
Scaling Errors:
Base Scaling = ±0.03%
Frequency Dependent Scaling = None at MAINS
Self‐heating Scaling = ±0.0002%*5
2
= ±0.005%
Temperature Scaling = none within 5C of the calibration temperature
Bandwidth Limit Scaling = none when using AUTO‐TRACK
Total Scaling errors = ±0.035% of reading
Floor Errors:
AC floor = ±37µA±(1.5µA/5A) at MAINS = ±37.3µA
Common‐Mode = assume connected to 230V mains = 4.6µA at 90° to voltage (so 0 to ±4.6µA depending on current phase)
Total Floor Errors = ±0.1149mA = 0.0023% of reading
Harmonic Amplitude Errors:
(H/N)
2
*0.3% of reading = (1/50)*0.03% = ±0.0006%
Is fundamental, so no further harmonic amplitude error
