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Re: UPS VA ratings (was: Re: [PLUG] equipment give-away on Wed evening)
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The model numbers on APC products usually correspond to the Volt-Amp rating of
the UPS. Volt-Amps = Volts (i.e. 120 VAC) * Amps (i.e. current draw). On AC
sources you have to multiply by the power factor because of the fact that
it's an AC sine wave source. Voltage and current aren't always in sync in an
AC load. That's why multiplying VA by square root of 2 (0.707) is a good
approximation of how much power you can draw from an UPS.
HTH,
Tom
On Tuesday 07 January 2003 17:50, Fred K Ollinger wrote:
> > On Tue, Jan 07, 2003 at 03:54:07PM -0500, Jeff Abrahamson wrote:
> > > I have two UPS'es (uninterruptible power supplies). They are 420 and
> > > 450 VA respectively. Remembering freshman calculus and root mean
> > > squares, this means they are rated 300 and 320 W respectively.
> >
> > Care to elaborate on that? I'm glad to admit my complete lack of
> > knowledge; I'd presumed those were model numbers. (I've got a pair
> > of 1100s, and it sounds like it was a good idea to go that large,
> > being as I've got a 450 W power supply in my IA32 machine...)
>
> Actually, IMHO, the model numbers (at least for apc products) are the
> voltages.
>
> Fred
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