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21January2021/Version 0
LEM International SA
Chemin des Aulx 8
1228 PLAN-LES-OUATES Switzerland
www.lem.com
Figures hereunder depict an example of graph to compare system accuracy (standard offset and
gain errors has been applied):
•
Left hand figure displays a simulated accuracy graph with the 4-wire measurement technique (or
perfect compensation of cable losses)
•
Right hand figure displays the same results when cable losses are not compensated, and no 4-wire
measurement is available.
-5
-4
-3
-2
-1
0
1
2
3
4
5
1
10
100
Er
ro
r (
%
)
Current (A)
Class B +
Class B -
1000V
150V
-5
-4
-3
-2
-1
0
1
2
3
4
5
1
10
100
Er
ro
r (
%
)
Current (A)
Class B +
Class B -
1000V
150V
Without compensation
With perfect cable loss compensation
Figure 25: Current accuracy graphs with and without cable loss compensation
When no compensation is implemented, the metering system does not subtract the losses of
electrical circuit; therefore the measurement energy is too high.
