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From: "Phil Allison"
References: <email@example.com> <firstname.lastname@example.org> <email@example.com>
Subject: Re: PFC question
X-Newsreader: Microsoft Outlook Express 5.50.4522.1200
Date: Mon, 2 Sep 2002 22:54:12 +1000
NNTP-Posting-Date: Mon, 02 Sep 2002 22:44:03 EST
Organization: Telstra BigPond Internet Services (http://www.bigpond.com)
"John Woodgate" wrote in message
> I read in sci.electronics.design that Phil Allison
> wrote (in ) about 'PFC
> The I^2R loss in supply wiring due to one PC's harmonics appears
> negligible *in isolation*, but the cumulative effects of a million or so
> on one supply system is certainly not. And the customer pays for it,
> anyway. For an SMPS without harmonic mitigation, the r.m.s. harmonic
> current is roughly equal to the fundamental current, say 1.5 A at 230 V.
> The resistive component of the supply impedance is typically 0.4 ohms
> for a 230 V 50 Hz system, although it rises for high harmonic
> frequencies due to skin effect. So the power loss is roughly 0.9 W per
> computer. A million computers cause 0.9 MW of wasted power. It makes no
> difference whether this million is composed of one or two units per home
> or one or two hundreds of units per large commercial building.
** 0.9 watts per PC eh? What if every PC user puts on the jug at the
same time - my gawd that would be a 2KW per PC overload or 2 (US) billion
watts for a million PCs - the mind boggles.
> > Domestic power consumption is still mostly resistive or PF = 1
> >type loads.
> Not in summer.
** Not at night either - everything is switched off !!!
And take into account that there is a growing switch to
> 'energy-saving' Compact Fluorescent Lamps (CFLs), which are quite
> severely non-linear loads.
** Not here in Aussie - hardly see then stupid things.
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