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Comments on Standardized way of measuring AC line frequency

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Standardized way of measuring AC line frequency

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In a general sinewave as below, is there a "right" way/"standardized" way to measure line frequency - and how do energy meters calculate that?

  • measuring pulse width of half-period, ie. time elapsed and then doing f=2/T
  • measuring pulse width of full-period, then f=1/T

Is there a need to average and filter assuming the reading is being taken with a microcontroller?

sinewave period

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1 comment thread

How Energy Meters Do It? is going to vary. The cheap ones assume a sine wave (results on a MSW in... (1 comment)
How Energy Meters Do It? is going to vary. The cheap ones assume a sine wave (results on a MSW in...
Spamalot‭ wrote 7 months ago

How Energy Meters Do It? is going to vary.

The cheap ones assume a sine wave (results on a MSW inverter may be surprising) and (likely) count frequency (or rather period, and derive frequency from that) on zero crossings. The expensive ones tend to look at the actual waveform and compute the actual RMS of that, but they likely still look at zero crossings.