Hi,
I was wondering if any thought had been given to voltage measurement in upcoming devices? Whilst current has to be measured at the meter tails, as that is the only place through which all the current flows, voltage will be (largely) constant if measured from any socket in the house.
Measuring the voltage allows for more accurate power measurements, since voltage can vary quite a lot during the day, and also for power factor to be taken into account - which is likely to change a lot depending upon the household equipment in use.
I have a little circuit run from an arduino that accomplishes this by using a current clamp for current (as you do), and measuring the voltage from the output of a AC-AC step-down transformer that plugs into a standard wall socket (and also powers the unit). In this way no messing with electrics is required, and more accuracy can be obtained...it would be great if something like this could be bought...
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