AS 62053.24:2018 Electricity metering equipment (ac)— Particular requirements
The test shall be carried out as follows: After the voltage circuits have been energized at reference voltage for at least 1 h, without any current in the current circuits, the maximum current shall be applied to the current circuits. The meter error shall be measured at sin ϕ = 1 immediately after the current is applied and then at intervals short enough to allow a correct drawing to be made of the curve of error variation as a function of time. The test shall be carried out for at least 1 h, and in any event until the variation of error during 20 min does not exceed 0,1 % for class 1 S and class 1 meters and 0,05 % for a class 0,5 S meter.
The difference between the percentage error when the meter is carrying a single-phase load and a balanced polyphase load at basic current I b and sin ϕ = 1 for direct connected meters, shall not exceed 1 ,5 % for meters of class 1 . At rated current I n and sin ϕ = 1 for transformer operated meters, the difference shall not exceed 0,7 % and 1 ,5 % for meters of classes 0,5 S and 1 S respectively.
When testing for compliance with Table 7, the test current should be applied to each measuring element in sequence.
8.3.1 The additional percentage error due to the change of influence quantities with respect to reference conditions, as given in 8.6, shall not exceed the limits for the relevant accuracy class given in Table 8.
1 ) For the voltage ranges from –20 % to –1 0 % and +1 0 % to +1 5 %, the limits of variation in percentage errors are three times the values given in this Table. Below 0,8 U n the error of the meter may vary between +1 0 % and –1 00 %.
2) The recommended test point for voltage variation and frequency variation is I b for direct connected meters and I n for transformer operated meters.
3) The purpose of this test is to check for current sensor saturation only. The test conditions are specified in 8.3.2 and in Annex A. The distortion factor of the voltage shall be less than 1 %. This test is not applicable for transformer operated meters.
4) The test conditions are specified in 8.3.3.
5) A magnetic induction of external origin of 0,5 mT produced by a current of the same frequency as that of the voltage applied to the meter and under the most unfavourable conditions of phase and direction shall not cause a variation in the percentage error of the meter exceeding the values shown in this Table. The magnetic induction shall be obtained by placing the meter in the centre of a circular coil, 1 m in mean diameter, of square section and of small radial thickness relative to the diameter, and having 400 At.