OpenEnergyMonitor Community

North America (United States) calibration values for EmonLib

Tags: #<Tag:0x00007f1be3efdcf0>

I am new to doing development with EmonLib, so please accept my apologies if this answer is hidden in plain sight on your website.

I would like to do a current measurement on an Arduino using your library, and I ran across this piece of code from your website:

#include "EmonLib.h"                   // Include Emon Library
EnergyMonitor emon1;                   // Create an instance
void setup()
  emon1.current(1, 111.1);             // Current: input pin, calibration.
void loop()
  double Irms = emon1.calcIrms(1480);  // Calculate Irms only      
  Serial.print(Irms*230.0);	       // Apparent power
  Serial.print(" ");
  Serial.println(Irms);		       // Irms

My question is how would I come up with the calibration values for the calcIrms and current methods, for the United States? Are these things constants that have already been calculated for the US?

I’m a software and algorithms guy, not a hardware/electrical guy, so this is confusing, and help is greatly appreciated!

I think all the calibration values are explained in Resources > Building Blocks. That you are in the USA makes no difference, the current calibration is dependent only on the CT and burden resistor that you use. You might find the values for your particular CT, if it is not our “standard” one, in the “EmonTx in the USA” page.