I have an installation with the same issue, in my case there is 230V at phase 1 and 180V at phase 3 but phase 2 reads only the current but no voltage.
Therefor the power import/export is based on incorrect values.
Did you find out what went wrong? I think I would go there and replace the meter, but if there is any idea what else might be the reason please let me know.
Thanks for your message. I haven’t resolved the issue yet either. What I do know is that the same meter has previously shown correct voltage readings on all phases, so it’s a bit puzzling.
I’ve recently bought a Shelly 3-phase meter as a replacement, but haven’t installed it yet. For now, I’m monitoring the system via CT clamps connected to a Myenergi setup. That gives me some insight — there are definitely some irregularities in the control logic, but nothing too serious at the moment.
With other parts of the renovation still taking priority, I’m planning to tackle this more thoroughly later, hopefully with Home Assistant integration to get better diagnostics.
Let me know if you discover anything useful on your end.
My problem with my system ‘developed’ in the mean time so here a second reply:
Interesting to hear you’re seeing something very similar — in my case, phase 3 has also stopped reporting voltage, although current is still being measured. This started about two weeks ago.
I’ve experimented with a VM-3P75CT as a temporary workaround. It does report voltages correctly, but the current readings are completely off — and as a result, the power values make no sense. That might be due to the very fragile CT clamps that come with it (or possibly just my clumsy handling); they tend to misalign easily or even snap.
I plan to have another go at installing those CT clamps, probably when I set up the Shelly 3-phase Pro I recently bought.
That said, I’m a bit surprised by the ET340 acting up like this. I’ve always considered it a fairly solid device.
One last thing I’m planning to check is the wiring to the ET340. I’ve had loose wires in the past, and although that typically causes different kinds of errors, it’s still worth ruling out.
Let me know if you make any progress — I’ll do the same.
Just a quick update on the ET340 issue we discussed.
Today I checked and connected the neutral wire to the ET340 — until now it hadn’t been connected (against the manual’s advice, I admit). After doing so, voltage readings are now back to normal on all three phases, and the system appears to be working correctly again.
So if you haven’t already, it might be worth checking the neutral connection on your side as well — it could be the cause of the missing voltage reading.
