Hi All,

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.*

Best regards.

Hi yilmazkircicek

We had to remove the total reactive power feature in the ADE7880 in order to make room for the Harmonic Engine. However, considering that the near future standards are going to be in compliance with just the fundamental reactive energy measurement, ADE7880 will be a really good choice. If ,at all, you need the total reactive energy measurement, you will need to use the harmonic engine to calculate all the harmonic values required and add it with the fundamental.

With regards to the settling time in harmonic measurements, you read it right. It will take 750 ms for every harmonic reading to settle. However, there is a accuracy Vs wait-time trade-off. If you can afford to be a little off, you can read the data quicker.

Regards

hmani