Paragraph 9 Margins of errorI1
England, Wales and Scotland
The error permitted for—
single phase and polyphase whole current meters and
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.
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.
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.
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.
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.
Annotations
Commencement
- I1
Sch. 3 para. 9 in force at 1.8.1998, see reg. 1