I'd like to revisit this topic, last discussed over a year ago in this thread:
If you've got a relatively long integration period (say 10 seconds), and a really nasty looking current signal, should tan-1(reactive/real) always come out pretty close to real/(Vrms*Irms), or does reactive energy get "lost" as discussed in that previous thread?
When I've got a nice clean current signal (leading or lagging), the power triangle as described above works fine, but the minute I start feeding it a really nasty load (like pictured below), my reactive energy readings come out way smaller than expected. For the signal pictured for instance, my calibrated readings come out at:
Vrms = 254V
Irms = 1.029A
RealPower = 217W
ReactPower = -10.3VARS
so the power triangle is kinda' broken.
What is the algorithm used for calculating ReactEnergy? I thought the device simply delayed one signal by 90 degrees and re-calculated the sigma(V*I). And yet when I apply that algorithm in my spreadsheet, with the data in the picture, I get a ReactPower of about 39.4VARS which works out much closer to what the power triangle would suggest. So it seems the device has some other algorithm for calculating reactive energy.