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Jeff Liebermann Jeff Liebermann is offline
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Default Kill-o-watt meter used on computer UPS - bad readings?

On Mon, 19 Sep 2011 17:41:18 -0700, "Bob F"
wrote:

I just unplugged the Belkin 1200 VA UPS powering my computer, and plugged it
into my Kill-o-watt meter.


What model Belkin UPS?
http://www.belkin.com/IWCatSectionView.process?Section_Id=206698
What model kill-o-watt meter?
http://www.p3international.com/products/

After the UPS quit beeping after power was restored,


Some UPS power supplies will stop beeping BEFORE they switch from
internally generated power back to wall plug power. It's not clear
from your description if the attached computah is running on UPS
power, or wall plug power.

the meter shows 7-11 watts being consumed by the UPS feeding the computer, which
is way less than the computer (quad core core-duo processor) uses.


Make and model of the computer? Anything else plugged into the UPS
such as a monitor, printer, modem, etc?

Does the killowatt have a problem reading accurately with UPS units?


Yes, sorta. If it's an old UPS, that doesn't have PF (power factor)
correction, the kill-a-watt will show a difference between VA
(volt-amps) and the real part of the power (watts). You can measure
the PF with the kill-a-watt (depending on model) and see if this is a
problem. However, the error is usually not very large and does not
account for a ridiculously low reading of 7-11 watts. The computah
should draw about 100 watts. The LCD monitor about the same
(depending on size). Add whatever for unspecified accessories. Take
the UPS out of the circuit and measure just the active loads plugged
into the UPS.

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