I recently read a post regarding use of a Kill-A-Watt device with inverters... The poster said something I'm going to have to check out (When I get the famous round-tuit that is)
Part of what he said I can verify one way or another I can state at this time "IT IS POSSIBLE", (I can not say it is true, just possible) I have seen other devices which use this type of system.
He said the Kill-a-watt gets it's power by using a capacitor to pass a portion of the 120vac to a rectifier power supply. As i said, I've seen this done in the past, Do they do it that way now... Kill-A-Watt says they are making changes.
He said that Capacitors pass more current at higher frequencies (This is true, 100% true, In fact I know the formulas)
The capacitor that was used was chosen for 60hz operation.
This is the part I can only partially confirm
Modified sine wave inverters output frequencies not only at 60hz, but at other frequencies as well, (higher frequencies) because of the somewhat "Square" nature of the wave form
But what he said is that TRUE SINE WAVE inverters atcually are the same as MSW inverters only instead of just 2 or 3 or 4 "Steps" they have hundreds of steps.
To test this all I need to do is plug in the venerable heathkit and hook it to my inverter (It is a 'scope) but I do know how to make a true sine wave and have worked with devices that do just that.
What I don't know is if Xantrex did it analog or digital