Hi,

I have one EmonPi but i have had some problems.

I need to calculate the real voltage and real current measurement?

For sample: I did “emonPi.power1=ct1.Irms” but the result is not real.

Thank you,

Regards.

Pedro Barbosa.

Hi,

I have one EmonPi but i have had some problems.

I need to calculate the real voltage and real current measurement?

For sample: I did “emonPi.power1=ct1.Irms” but the result is not real.

Thank you,

Regards.

Pedro Barbosa.

Can you explain what you mean by “but the result is not real”, and what you really want?

The rms current is the current that you would measure with a true rms meter. It is not the real component of current. Likewise, the rms voltage is the voltage that you would measure with a true rms meter.

I explained bad, with ct2 I calculate the power and with ct1 I calculate the Irms in the same cable, when doing power/Vrms the calculated value is not the same as Irms read. Understand my problem?

Should I do something wrong in the code?

Do you have any sample for the calculated Irms?

What you are doing is correct. But voltage multiplied by current gives you the apparent power. That is not normally the same as real power. The difference, unless it is due to the inevitable errors arising from component tolerances, will be because your load is not a pure resistance.

You can read more in any good electrical engineering textbook, or here.

To get the rms current, you will need to edit and reload the sketch. The emonPi Atmega328 Discrete Sampling sketch does calculate rms current, but it’s not used and not sent to emonHub as part of the data structure. I’m afraid you will need to extract the currents and add them after the call to calcVI( ):

`emonPi.Irms1=ct1.Irms;`

etc, recompile and reload the sketch and edit your emonhub.conf to accept the new values. How to recompile and re-load is in the Wiki, I believe.