[CentOS] wich apc ups?

Brent L. Bates blbates at vigyan.com
Tue May 29 19:16:07 UTC 2007


     The do not say it because Watts =  Volts x Amps ONLY in DC or 100%
resistive AC loads.  If it is an inductive load, it isn't that simple, that is
why they have `VA', `Volts x Amps', ratings.  There can be a phase difference
between the voltage and current, thus the `Wattage' is less than the `VA'
rating.  A `1500VA' UPS is going to list less than `1500 Watts'.  Just check
out any UPS manufacturerer's specs. and the `VA' and wattage ratings will be
different.  To be safe, I take the voltage rating of the equipment and
multiply it by the current rating to come up with the `VA' rating.  I know APC
says to not go over 80% of the UPS rated load, so take your `VA' value and
divide by 0.80 to get the `VA' rating you want your UPS to be.  This will
probably give you an UPS a little bigger than you need, but it is better to be
a bit too large than too small.

-- 

  Brent L. Bates (UNIX Sys. Admin.)
  M.S. 912				Phone:(757) 865-1400, x204
  NASA Langley Research Center	  	  FAX:(757) 865-8177
  Hampton, Virginia  23681-0001
  Email: B.L.BATES at larc.nasa.gov	http://www.vigyan.com/~blbates/




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