Three-Phase Three-Wire

Looks really interesting, @overeasy !
Adding a question either for you or any others in ths thread; For an European 3-phase 230V (no neutral wire) system with 19 1-phase and two 3-phase breakers, would this be a better solution than using two current ESP8266 systems? If my understanding is correct, I would need 3 CTs for the mains, 19 CTs for the 1-phase breakers and 4-6 CTs for the two 3-phase breakers…? I am not sure this is even possible on two gen 5s given that the 3-phase voltages from the mains must be shared somehow?

The ESP32 is not tracking to be a mature certified product. It will probably be a DIY resource when I have time to work on it more.

That said, Three-Phase 3 wire can be handled easily by the ESP8266 V5.1 unit. Each unit has the capability for 15 inputs, one of which must be voltage. The overwhelming number of three-phase users use one voltage reference with satisfactory results. You can use three voltage references for increased accuracy but that reduces the number of CT inputs from 14 to 12. I recommend going with one voltage reference (derived reference).

With three-wire systems, three-phase loads can be measured with two CTs. You would use that for the two three-phase breakers as well as the mains. That adds up to 25 CTs where two IoTaWatt can handle 28 (derived reference) or 24 (direct reference).

It’s altogether possible that you can get a good understanding of your usage with just one IoTaWatt using 2 for mains, 4 for the three-phase breakers, and 8 for individual circuits or groups of circuits on the same phase.

If you use two units, you would need to have them upload to influx or Emoncms if you want to aggregate the data for combined reporting.

Thank you so much for your in-depth reply, @overeasy . It made me go all in on this :slight_smile: I am doubling down on two 5.1’s then.

Just for my own education, I thought European 3 phase was 440, (or 380 in the old day?), between phases, and that the ~230 volt levels would be phase to neutral (or ground). I spent a fair amount of time in Europe as a marine engineer, and never once did I see 230 three phase. (i.e., 230 between the phases) However, it was almost 40 years ago. (hence the 380 reference)

Good question. Throughout most of the 230V world, it is 230V phase-neutral and 400V phase-phase. Those are four-wire three-phase.

In Norway, they use three-wire three-phase where there is no neutral wire. It’s delta rather than wye with the phase-phase voltage being 230V. They typically break it down into three separate 230V branches, but three-phase 230V is available for motors or high-power appliances.