ups units

Glen Kaukola glen at
Thu Jun 5 15:39:18 EDT 2003

Hi everyone,

I've got a question about UPS units.  If they're rated at 1500VA, then 
how many computers with 400 watt power supplies should they be able to 
handle?  And how many computers with 550 watt power supplies?  If 
someone could let me know how you calculate the answer I'd really 
appricate it.

The reason I ask is because we have a number of Cyberpower and APC UPS 
units rated at 1500VA.  They each have 2 computers plugged into them, 
and seemed to be working fine, as me and my boss tested them by 
unplugging each while the computers plugged into them were running.  But 
recently we had a power spike or whatever you'd call it, that lasted 
less than a second, and afterwards I noticed that many of the computers 
plugged into the Cyberpower units had rebooted.

I contacted the company we purchased the Cyberpower units from, and he 
in turn contacted Cyberpower.  Cyberpower informed him that there 
shouldn't be more than one computer plugged into each UPS unit, and said 
something which I didn't understand about 12 amps, 125 volts, and 400 X 
2 watts being more than 1500AV.  It all sounded rather fishy to me, so I 
was hoping that somebody on this list could clear things up for me.

Thanks in advance,

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