# The Meters (Certification) Regulations 1998, Paragraph 9: Margins of error

Extent: E+W+S

(1) The error permitted for—
(a) single phase and polyphase whole current meters and
(b) single phase and polyphase transformer operated meters when tested with transformers connected
shall not exceed plus or minus 1.9 per cent. for test numbers 1, 2, 3 and 4 in table 2.
(2) The error permitted for both single phase and polyphase transformer operated meters, when tested without transformers connected, shall not exceed plus or minus 1.4 per cent. for test numbers 1, 2, 3 and 4 given in table 2.
(3) The error permitted for polyphase whole current meters and transformer operated meters, when tested with transformers connected, shall not exceed plus 2 per cent. or minus 3 per cent. for test numbers 5 and 6 given in table 2.
(4) The error permitted for polyphase transformer operated meters, when tested without transformers connected, shall not exceed plus 1.5 per cent. or minus 2.5 per cent. for test numbers 5 and 6 given in table 2.
(5) Where current and voltage transformers are intended to be used with meters and are not tested connected to a meter then the error of the transformers at any load point throughout the rated range shall not exceed 0.5 per cent.
TABLE 1
Influence quantities
Reference value
Tolerance
Ambient temperature
Reference temperature or, if not indicated, 23°C.
±2°
Meter position
Vertical
±3°
Voltage
Reference voltage
±1.5%
Frequency
Reference frequency of 50Hz
±0.5%
Voltage and current waveform
Sinusoidal form
Distortion factor <5%
External magnetic induction at the reference frequency (paragraph 5(5))
Zero
Induction value that does not produce a relative error variation of more than ±0.3%
TABLE 2
Test load in terms of marked current
Test number and load
Power factor
Basic/maximum
Maximum continuous
Long range
Short range
Meter type
Polyphase meter load
1 (high)
1
Imax
100%
100%–200%(Note 1)
100%–125% (Note 1)
Single and polyphase
Balanced
2 (intermediate)
1
Ib or 125%Ib
Any load between 25%–75% of the value specified for test number 1 (Note 1)
Single and polyphase
Balanced
3 (low)
1
5%Ib
1.67% (Note 2)
5%
5%
Single and polyphase
Balanced
4 (inductive)
0.5 (Note 3)
Ib or Imax
100%
The same value selected for test number 1
Single and polyphase
Balanced
5 (element)
1
Ib
100%
The same value selected for test number 1
Polyphase
One phase loaded in turn
6 (inductive) (element)
0.5 (Note 3)
Ib
100%
The same value selected for test number 1
Polyphase
One phase loaded in turn
Note 1 Where a range is given, any value within that inclusive range may be selected.
Note 2 For maximum continuously rated prepayment meters, the low load test value may be twice the value shown.
Note 3 For test numbers 4 and 6, the inductive power factor shall be between 0.45 and 0.55 inclusive.

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Source: https://www.legislation.gov.uk/uksi/1998/1566/schedule/3/paragraph/9 (the official version)
Page: https://openlegislation.uk/meters-certification-regulations-1998/schedule-3/paragraph-9
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.