David wrote:

.... snip ...

This all started with a discussion of the Kill-A-Watt meter which
measures RMS voltage, RMS current, and Watts. Maybe the following
will clear some of the confusion.
The computation of RMS was described in an earlier post. The
product of RMS voltage and RMS current is Volt-Amps. Power, and
therefore power consumption (Watts=power/second), is computed by
the integration of the product of instantaneous volts and amps
over time. The power factor then becomes Watts/Volt-Amps. The
accuracy of the wattage and RMS calculations with voltage or
current waveforms that change rapidly is related to the sampling
rate used in the integration. Any wave shape for either voltage
or current will produce mathematically meaningful RMS and power
measurements. I am sure someone will point out any mistakes I have
made here.

You omitted that a periodicity is required. An infinite wavelength
is also allowable. :-)

BTW, please do not remove attributions for material you quote.

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
http://cbfalconer.home.att.net



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