As the emon’s are now up and running, the next big thing needs to happen, calibrating the sensors..
There is a good wiki on how and what to do:
http://openenergymonitor.org/emon/buildingblocks/calibration
What do we need to calibrate?
emonTX:
- AC Voltage, in combination to the AC-AC power adapter
- AC current used, compared to what is read by the coil sensors
Following the guide, these number reflect the Node10:
The new calibration coefficient can be calculated by:
New calibration = existing calibration × (correct reading ÷ emonTx reading)
const byte Vrms= 226; // Vrms for apparent power readings (when no AC-AC voltage sample is present) const float Ical1= 86.96; // (2000 turns / 22 Ohm burden) = 90.9 const float Ical2= 86.43; // (2000 turns / 22 Ohm burden) = 90.9 const float Ical3= 87.01; // (2000 turns / 22 Ohm burden) = 90.9 const float Ical4= 15.97; // (2000 turns / 120 Ohm burden) = 16.67 //const float Vcal= 260; // Calibration for EU AC-AC adapter 77DE-06-09 float Vcal= 242.2;
I used a heater which was using just about 6A (5.99A) constantly. Strange enough the power readings where at about 40W.. so there is still something strange 😉