I need to measure small amounts of power consumption coming from a device like a television or a PC monitors. I think that the SCT-013-000 sensor sold with emonPi is too big for this purpose, so I bought an SCT-013-005 sensor which is suitable for small amounts of power consumption.
I read some other threads in this forum to understand how to connect alternative CTs to the emonPi. Since the SCT-013-005 CT already contains a burden resistor, I simply removed the 22Ω burden resistor from the emonPi and connected the sensor to the emonPi.
According to this guide (https://learn.openenergymonitor.org/electricity-monitoring/ctac/ct-and-ac-power-adaptor-installation-and-calibration-theory) I’ve also calibrated the sensor with a value of 5.
However, when trying to measure the power consumption of a pc monitor, I’m getting 0 W, -1 W and 15 W respectively in off, standby, and on states. Except from the on and off states, I can’t understand why I’m reading a negative value while the monitor is in standby.
Am i doing something wrong while calibrating the sensor?