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Input power factor:
An incandescent light bulb or a resistive heating element draws power from the power line in a nice sign wave. A personal computer draws no power for most of the 60hz cycle; only at the top of the 60hz wave it draws a very large pulse of current. A motor draws power slightly delayed or behind the voltage. The power company likes ‘resistive’ loads and dislikes PCs and TV sets that pull power only at the peak, causing the sign wave on the power line to flat top. If your UPS has a good power factor it will look more like a resistor and less like a PC, from the power company’s point of view.
Output power factor:????
It could indicate the UPS can work with loads that have bad PF.
OR
Many UPSs produce a modified sign wave. That is to say their output is not sign wave. A good clean sign wave will have little harmonics and thus have a good PF. It might indicate a merit of how clean the harmonics are. How close the output is to a sign wave.
If you want to know that your PC pulls twice as much power as your TV then you have a good meter. If you want to measure very accurately then you have a bad meter.
A watt meter is not simple.
Most low cost “watt meters” are actually current meters with watts written on the display. They assume the voltage is 115 volts. If you line voltage is high or low then the meter will be off.
Most meters do not account for poor power factor. With resistive loads the read good but with a PC they will read 25% off.
There is the old average verses RMS problem.
Some meters read (average voltage) X (average current). It is more accurate to measure (instantaneous voltage) X (instantaneous current) then average over time.
Your meter is far better than no meter but not as good as a $500 meter.
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