I have an EmonPi with a CT connected to one cable on my domestic supply between the meter and the distribution board. I also have a reference power source connected to the mains and an optical pulse reader on the meter.
I’m finding that the values from the CT are significantly over-stated. Is there something I need to do to calibrate the reading? There isn’t a whole lot of wiggle room in the placement or alignment of the CT due to the positioning of the cables.
Over the last 24 hours the meter visual reading increased by 13kWh. The meter doesn’t seem to report any decimal places, so the granularity available is only 1kWh.
The optical pulse counter reported 12,596 pulses. This equates to ~12.6kWh and is close enough to the difference in the meter reading given the granularity available.
I have another set of pulse counters on 9 individual mini-meters on each circuit around the house (which account for all the power fed through the utility meter) and it came back with 12.4kWh based on the pulses from each of the meters added together. For my purposes this is close enough to the 12.6 and 13kWh readings from the other two sources.
Meantime the CT reported 19kWh. That is ~50% higher than actual based on the utility meter. Does anyone have any ideas what might be accounting for this difference, and whether there’s anything I can do to correct it? I can live with the pulse readings, but wouldn’t mind having the CT chime in as well so that I could notice if/when something went wrong with the pulse meters.