[CentOS] wich apc ups?

Tue May 29 20:25:42 UTC 2007
Peter Kjellstrom <cap at nsc.liu.se>

On Tuesday 29 May 2007, Dan Halbert wrote:
...
> Watts = Volt-Amps IF the power factor is =1. Power factor is based on
> the reactance of the load.  A purely resistive load has a PF=1. Google
> << watts vs volt-amps >> for more info, e.g.
> http://www.vabiomed.org/documents/tech0003.htm.
>
> The power supplies I have measured in servers have a power factor close
> to 1. But I have measured consumer machines with a power factor
> considerably different than 1.

Worth knowing here is that even if you have something with pf=1 you wont get 
those 1500 watts out of a 1500VA UPS. UPSes are often, what they call, power 
factor 0.9 or 0.8. This means that you'll never get more than 1200W or 1350W 
out of a 1500VA UPS regardless of the pf of your load.

That said, modern powersupplies I've tested lately have all been better than 
0.9 and most even >0.97.

/Peter
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