Hi there, I finally got my emonTx shield up and running and its producing currents and power for all 4 CTs, passing the data via serial to the RPi running emonHub.
However, even without the CTs having wires inserted I am receiving measurements of around 0.2-0.4 Amperes, while they should be zero. The CTS are of course closed. Is this normal? Being an electrical engineer I think I do understand the calibration procedure for (close to) full load, however, I am worried that there might be an offset at zero load. 0.4 A is not nothing.
Is there a way of calibrating the current offset to zero? Thanks for any help with this.