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

Extent: N.I.

(1) The maximum 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% for test numbers 1, 2, 3 and 4 in Table 2.
(2) The maximum error permitted for both single phase and polyphase transformer operated meters, when tested without transformers connected, shall not exceed plus or minus 1.4% for test numbers 1, 2, 3 and 4 given in Table 2.
(3) The maximum error permitted for polyphase whole current meters and transformer operated meters, when tested with transformers connected, shall not exceed plus 2% or minus 3% for test numbers 5 and 6 given in Table 2.
(4) The maximum error permitted for polyphase transformer operated meters, when tested without transformers connected, shall not exceed plus 1.5% or minus 2.5% for test numbers 5 and 6 given in Table 2.
(5) Where current and voltage transformers, which are intended to be used with meters, are not tested connected to a meter then the total error of the transformers at any load point throughout the rated range shall not exceed 0.5%.
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 50Hz
± 0.5%
Voltage and current waveform
Sinusoidal form
Distortion factor <5%
External magnetic induction at the reference frequency
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
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.
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
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

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Source: https://www.legislation.gov.uk/nisr/1998/444/schedule/3/paragraph/9 (the official version)
Page: https://openlegislation.uk/meters-certification-regulations-northern-ireland-1998/schedule-3/paragraph-9
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.