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Kill-o-watt meter used on computer UPS - bad readings?

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Bob F

Jan 1, 1970
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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?
 
S

Sylvia Else

Jan 1, 1970
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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?

The reading seems strange (typically one would expect it to show a
higher than true figure), but cheap power meters often have difficulty
with anything other than appliances that behave like resistive loads.
Neither the UPS itself nor the PC is likely to do so.

Sylvia.
 
B

Bob F

Jan 1, 1970
0
Dave said:
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...

I'll try bypassing the UPS when my computer is not busy and report the results
later.
 
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Bob F

Jan 1, 1970
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Bob said:
I'll try bypassing the UPS when my computer is not busy and report
the results later.

I just tried plugging the computer directly into the Killowatt meter, and get
the same results. It shows 6 watts with the computer connected, and 9 with it
on. The killowatt just doesn't see the computer.
 
M

mike

Jan 1, 1970
0
Bob said:
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?
I tried a Killawatt P4400 on my old dell.
Reads 100W/140VA.

Do you know if your Killawatt is working?
Try it on an incandescent light bulb.

It's possible to exceed the crest factor capability
of the meter, but your computer shouldn't do it.

You can work around that problem by measuring
a light bulb then adding the computer and subtract
the light bulb watts.
 
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