More food for thought.....
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This is typical for measurements according to IEC 61000-3-2, IEC 61000-3-12, IEC 61000-4-7, EN 61000-3-2, EN 61000-3-12 and EN 61000-4-7 where
a 200 ms window is required for a 50 Hz fundamental frequency.
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I am some how lost here, GW Instek for example presents compliant power meter to EN 61000-4-7, when their top tier
GPM-8330/8320 it has different data update timing per situation.
Copy / Paste from their documentation. 1) When the data update interval is 100 ms the numeric display 10 items display update interval is 200 ms.
2) When the data update interval is 100 ms or 250ms and the numeric value display is set to
Matrix or ALL Items display update interval is 500 ms.
3) The waveform display update intervals are approximately 1s
4) Accuracy changes caused by data update interval:
When the data update interval is 100 ms, and Auto, add 0.05% of reading to the 0.1 Hz to 1kHz accuracy.
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No there is no love sentiment between me and GPM-8330/8320, I do dislike the steeping of current ranges
0.5 A/1 A/2 A/5 A/10 A/20 A.
500mA as smaller range this is too large for my taste.
From the other hand,
GPM-8310 while it seems as a complete solution, fastest data update interval this is
250ms, and this makes it slow and not compatible to EN 61000-4-7.
At the end of the day, if you care to select an instrument at 1500 Euro price point, every little detail counts.