Paragraph 9 Margins of errorI1

Northern Ireland

(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)

Imax

100%

100%-200% (Note 1)

100%-125% (Note 1)

Single and polyphase

Balanced

2 (intermediate)

Ib or 125% Ib

Any load between 25%-75% of the value specified for Test Number 1

Single and polyphase

Balanced

3 (low)

5% Ib

1,67% (Note 2)

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)

100%

The same value selected for Test Number 1

Polyphase

One phase loaded in turn

6 (inductive) (element)

0.5 (Note 3)

100%

The same value selected for Test Number 1

Polyphase

One phase loaded in turn

Annotations

Commencement

I1: Sch. 3 para. 9 in operation at 1.2.1999, see reg. 1