Hi,

maybe a simpler approach:

- do a lowpass filtering of current and voltage (it changes phase angle,
but do not mind as both change in the same way)
- detect the zero-crossing point for both, regarding only voltage increase
- measure the time between them (lag)

power_factor = cos(tlag / tper * 2 * pi)

(there is a divisor of 4 in both side but disappears).

I hope this helps.

Regards,

Imre


On Tue, 7 May 2002, Barry Gershenfeld wrote:

> I suspect that if that "stuff" is on the power line, then it is
> going into your load, so measure it and report it.
>
> Take many samples of volts and amps.
> For each sample, calculate rms volts, rms amps, and rms watts.
> After you have enough samples, multiply rms volts times rms amps.
> It (rms VA) will be larger then rms watts.  That's your power
> factor, which I think (anyone?) is just (rms watts)/(rms VA)
>
> Barry
>
>
>
>
> At 02:40 PM 5/7/02 -0300, you wrote:
> >Hello piclist,
> >
> >  Anyone can suggest a method to measure power factor in AC lines.
> >  Specially considering noisy enviroments and poli-harmonics
> >  conditions.
> >            Thanks in advance.
> >
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