Our end product will not be a energy metering device but need to measure some required parameters.
We were evaluating the ADE7880 for our project and have seen the document AN-1127 that states ADE7880 does not compute tatal reactive power / energy as done by ADE7878.
- Why total reactive power/energy is not calculating ? Is not it required for industrial reactive energy metering application ? Fundamental reactive measurement is enough ?
- Can I calculate the total value by reading fundamental and all harmonic reactive values ? ( It will be a little bit time consuming. Because only 3 harmonic can be calculated at once.) Or calculation from apparent and active power/energy will be more efficient ? Or any other idea ?
- Datasheet mentions about a settling time (approx. 750ms) for harmonic calculations. Is this settling time only necessery after power up/reset or ADE7880 need this settling time whenever I changed the HX, HY and HZ index or phase? If second option is true; it requires (63/3) * 0.75 * 3 = 47.25 seconds for 63 harmonics of 3 phase data update Please see the phrase from data sheet below; Did I missunderstend the explanation?
Configuring Harmonic Calculations Update Rate
The ADE7880 harmonic engine functions at 8 kHz rate. the moment the HCONFIG register is initialized and the harmonic indexes are set in the HX, HY and HZ index regthe ADE7880 calculations take typically 750 ms to settle within the specification parameters.