From: John Tserkezis 
Reply-To: Fidonet AVtech Echo 

Bob Lawrence wrote:

>  Have a look some time... the pulse straddles the peak. As the
> current-pulse charges the capacitor, the output voltage rises to meet
> it, which crosses the peak unless there is *zero* source resistance
> in the circuit.

  Well, yeah, but it's only a little bit.

>  But in any case, I was speaking about the pulse itself, not its
> precise placement. A pulse *anywhere* in the sinewave cannot be PF
> corrected. The point of PF is that the generator ougth to be loaded by
> the same in-phase waveform it produces, or it makes the generator
> "cog" and run unevenly.

>  The only solution for a pulse load is to shift the phase of the
> *supply* to each house (or street, whatever), so that the loads
> average out.

  I'm not even sure how they do this passively.

> JT> Kinda, there are "passive" designs around that effectively
> JT> shift the pulse later, it isn't perfect, but plenty good enough
> JT> to keep the power authorities happy.

>  So far... because the main drain is resistive hot water and motors,
> but when SMPS rules okay, they're going to have to get serious. The PF
> spec is just silly.

> JT> Just repeating what I've heard, though, since then, there are
> JT> still plenty of (current model) 500+W PC power supplies that
> JT> aren't power factor corrected. 

>  The reality is that *none* of them are... is terms of what they
> call power factor correction actually reducing norty loads on the
> generators. It's a joke that we go along with because it makes someone
> who writes the stupid specs, happy.

  A guy at work who's seriously into overclocking (I call them tight arses, but 
they insist it's not because of that).  They pay stupid amounts of money on 
tightly specced power supplies, and they say those are PF corrected.

  I haven't had the chance to take one apart and see how they do it though. 
Would be interesting.

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