[geeks] UPSs

Joshua D Boyd jdboyd at cs.millersville.edu
Tue May 7 22:13:57 CDT 2002


On Tue, May 07, 2002 at 09:12:26PM -0400, Tim H. wrote:
> VA (voltamps) is a power rating, no time vector involved.  It says how 
> much power it can dish out without letting out the magic smoke.  The size 
> of the batteries determines how long it will put out that power before the 
> batteries die.  You spec the UPS by the amount of power you need to supply, 
> then buy the biggest one at that rating you can afford.  

I see.  So how is the "biggest" one measured?  Ie, what to look for in specs?

BTW, VA as in Volts times Amps is the same as Joules per Coulomb times 
Coulombs per Second, so the Coulombs cancel leaving Joules per Second.
So, VA has a time vector.  It is a measure of power per second.  Usually
Volts time Amps is just Watts though.  Not sure why they don't just advertise
that way.

-- 
Joshua D. Boyd



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