In article , Bob F wrote:

I just unplugged the Belkin 1200 VA UPS powering my computer, and plugged it
into my Kill-o-watt meter. After the UPS quit beeping after power was restored,
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.

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

What does the meter read, if you connect the computer to it directly,
and entirely bypass the UPS?

Most of these consumer-grade "UPS" systems are *not*. That is, they
aren't "uninterruptable" - they are "standby power supply" devices.
During normal operation, when the AC mains are up normally, they
actually connect the load (PC) directly to the mains... their own
output circuitry is switched off. All they have running, internally,
is monitoring circuitry, and a trickle-charger for the battery. The
"UPS" only disconnects the load from the mains, turns on its inverter,
and begins generating AC power to feed to the load.

So, if the Belkin isn't beeping, it's probably just routing the AC
mains power through to the PC, and you'd find the meter reading almost
the same as if you plugged the PC directly into the meter...

.... and this might not be a terribly accurate figure. My recollection
is that some of these "power consumption meters" don't do a very
accurate job of measuring power usage being drawn in pulses (i.e. by
a non-resistive load). Your computer's power supply may be presenting
a load that the Kill-a-watt is having trouble analyzing.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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