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
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
What model Belkin UPS?
What model kill-o-watt meter?
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.
Make and model of the computer? Anything else plugged into the UPS such as a monitor, printer, modem, etc?
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.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.