Mailinglist Archive: opensuse (3572 mails)

[Dave Plater <davejplater@xxxxxxxxx>]

Carlos E. R. wrote:
> The Sunday 2008-02-17 at 15:09 -0800, Randall R Schulz wrote:
>
> > So the RMS voltage and the resistance allow you to compute the average
> > power over a full cycle. (Note that power is voltage squared divided by
> > resistance and that this is the real reason that RMS is the way to
> > compute the average power dissipation in a resistive circuit.)
>
> For power you have to consider the power factor, the cosine of the 
> phase angle - which for a resistor is 1, of course.
>
> > But if you have an instantaneous power function and apply the RMS
> > calculation to that, you'll get a value with no physical meaning.
>
> which is why I said the first day that I don't know how good are those 
> measurement gadgets when applied to a swith mode power supply.
>
>
> Here:
>
>   http://www.analog.com/en/
>
> Search for the ADE7756AN  (Active Energy Metering IC with Serial 
> Interface)
>
>
> -- Cheers,
>        Carlos E. R.
It looks as good as the designer that uses it, besides a switch mode 
supply still converts the mains to DC, and smoothed before switching it 
through a ferrite core transformer. There are rules about sending high 
frequencies back up the mains supply. Both the power going in and out to 
MB is buffered so to speak.
Dave
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