From: muratlanne@gmail.com   
      
   "danny burstein"  wrote in message   
   news:j5a1b8$nv3$1@reader1.panix.com...   
   > In  "Jim Wilkins"    
   > writes:   
   >   
   >>> Does the killowatt have a problem reading accurately with UPS units?   
   >   
   >>I just checked a KAW P4400 with two stepped square wave inverters and a   
   >>60W   
   >>incandescent lamp. It shows 111V 55W and 129V 59W. I see odd readings on   
   >>the   
   >>input of a UPS too, but they have always been higher than expected.   
   >   
   > Have you had a chance to check the power draw   
   > of that "60 watt" lamp when it's plugged directly   
   > into the outlet (that is, no UPS inline)?   
      
   It's my standard inverter test load. The wattage varies with line voltage of   
   course, and probably the age of the bulb as tungsten evaporates off the   
   filament. Typically this one reads 55W at 120V. This morning the line is at   
   122.6V and the bulb draws 58W.   
      
   I don't have another way to measure AC power that's significantly more   
   accurate than a KAW. Except for one old Amprobe my clamp-on current meters   
   pretty much agree with it. An in-cal analog oscilloscope with voltage and   
   current probe is typically assumed to be accurate to ~3%, and mine are long   
   out of calibration.   
      
   jsw   
      
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