3 of 5 people found the following review helpful
Works just fine...but didn't work for long.,
This review is from: P3 P4400 Kill A Watt Electricity Usage Monitor (Tools & Hardware)
Upon testing a new appliance, this gadget produced the following numbers:
Amps : 3.08
The standard calculation is Amps X Volts = Watts. Using the standard calculation, the numbers returned are:
3.08 amps X 115.2 Volts = 354.81 watts
So which is the correct number, 268 watts or 354.81 watts?
Update: As noted in the comments section, power factor has to be taken into consideration with 120 volt electrical sources. Review updated - this gadget works just fine.
Update: Died a horrible death today while testing a window air conditioner rated at 1110 watts (120 volts). This is no where near the 15 amps / 1800 watt rating of the gadget.
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Initial post: Apr 22, 2011 6:42:53 PM PDT
Last edited by the author on May 4, 2011 2:15:54 PM PDT
Watts = volts X amps is only true for DC devices, and AC devices that have a power factor of 1, such as purely resistive loads ( for instance, a conventional light bulb). Otherwise, the calculation is Watts = Volts X amps x power factor. When the Kill a Watt device shows a wattage number, the power factor is already included in their calculation. The Kill A Watt also tells you the power factor of the device if you want a separate figure. What was that power factor number , and if you include it in the calculation of volts x amps x power factor, does the wattage work out more closely ?
In reply to an earlier post on Jun 25, 2011 11:18:15 AM PDT
H.F. Mudd says:
My mistake - Thank you for the correction.
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