True RMS : what kind of measure?


#1

Hello,
Could you say me, how the active power (W) and FP are calculated ? Today, electric load are non linear, can you use FFT algorithm ?`
regards
stef


#2

Per sample wave, defined as the time when voltage crosses zero until it crosses again two more times:

  • Voltage and current pairs are sampled every 26μs.
  • RMS voltage is the Root of the Mean of the Squares of the voltage samples.
  • RMS current is the Root of the Mean of the Squares of the current samples.
  • Real (active) Power is the mean of the product of voltage and current of each sample.
  • Everything else can be derived from those measurements.

There is no FFT calculation.


#3

Thank you, that’s fine.