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Compatibility of ADE7880 RMS Calculation with IEC-61000-4-30

Question asked by MHossein on Jul 20, 2017
Latest reply on Aug 21, 2017 by aheredia

Hello,

According to IEC-61000-4-30, for class A energy meters :

The measurement shall be the r.m.s. value of the voltage magnitude over a 10-cycle time
interval for 50 Hz power systems or 12-cycle time interval for 60 Hz power system. Every
10/12-cycle interval shall be contiguous, and not overlapping with adjacent 10/12-cycle
intervals...

The 10/12-cycle values are then aggregated over 3 additional intervals:
– 150/180-cycle interval (150 cycles for 50 Hz nominal or 180 cycles for 60 Hz nominal),
– 10 min interval,
– 2 h interval.

As we know, the first method ADE7880 uses to calculate rms voltage and current  is to low-pass filter the square of the input signal (LPF) and take the square root of the result and this calculation takes place continuously (although the update rate of rms registers is 8 kHz) without any specific time interval for restart the calculation.

How can we use ADE7880 rms results for satisfying the standard? Is it enough only to read rms registers every 10-cycle (for 50 Hz system) and use them as a base for aggregation (over 3 s, 10 min or 2h time intervals according to the standard)?

Thanks.

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