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Non-zero readings #20

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CatalanCaptain opened this issue Feb 18, 2020 · 1 comment
Open

Non-zero readings #20

CatalanCaptain opened this issue Feb 18, 2020 · 1 comment

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@CatalanCaptain
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After setting all up if I plug the CT sensor but with no wire through it, I have a non-zero readings, about 0,1A.
I suspect that this is caused by the difference on the voltage divider resistors, that gives a reference voltage something different than 3,3V/2=1.65V.
It would be interesting to implement some kind of calibration routine to add an offset and get more accurate readings.
Also, when connecting a (theorically) 2000W air heater, readings go around 1800W-1900W. But in this case, I don't know if it's related with the same issue.

Thanks for your time and dedication @Savjee

@Savjee
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Savjee commented Feb 21, 2020

For calibration, you can try playing with emon1.current in the main file: https://github.com/Savjee/home-energy-monitor/blob/master/src-esp32/src/main.cpp#L56

The second parameter is a calibration value. More details about it here:
https://learn.openenergymonitor.org/electricity-monitoring/ctac/ct-and-ac-power-adaptor-installation-and-calibration-theory?redirected=true

As for a calibration routine: that's an interesting idea, but it would require some additional hardware. A button or so to trigger it.

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