Comparison of End‐User Electric Power Meters for Accuracy

4. Results
4.1. Summary about accuracy
Each meter was tested against the six loads as described in 3. The error ranges
were derived from the relative deviations of the meter reading and the reading of
the reference device. The average errors in absolute figures were also calculated
for all devices, and their average was 9.2% (standard deviation = 6.3%). The
average errors associated with individual devices are displayed in Figure 2 below:
Verkkokauppa.com FHT-9999
Hong-Kong FHT-9999
19 %
18 %
Clas Ohlson PM300
15 %
Motonet PM300
LIDL PM333
12 %
12 %
Velleman NETBSEM2
BeAw are prototype
Christ-Elektronik CLM200
6 %
6 %
6 %
Clas Ohlson EMT707CTL
Technoline Cost control
Plogg Blu v2.0
2 %
3 %
3 %
Average error
0 % 5 % 10 % 15 % 20 % 25 %
Figure 2. The average errors in each meter in comparison to the reference value.
All errors are presented as absolute values deviating from the reference.
We found no relation between the accuracy of the device and its retail price (see
Figure 3). This was not surprising in the given price range, because the
manufacturing costs for the tested devices are likely very similar. Bit surprising
was that the two more expensive devices did not perform significantly better.
Weighted tolerance score
3.00
2.50
2.00
1.50
1.00
0.50
Price versus accuracy
Price in Euro
0.00
0 20 40
Figure 3. Relation of price and accuracy. The two most expensive meters excluded.
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