this is kind of a simplified question of my previous post, after some investigations.
I have a 3-phase ESS with 3x Multiplus-II 5kVA, no loads connected, external control, pylontech battery set.I use it to store excess solar produe and do grid assist. Main grid is always connected and able to provide 20kVA total (3 phases). I use an ET-340 to measure net grid in/outflow and command the ESS via Modbus/TCP as needed.
Very simple installation - connected to my internal grid for grid assist only on AC-In. to say that again, nothing connected to AC out.
The system only worked for a few days (less than 30 days definitely). Now it is dead.
Here is the sequence of events:
- overload error on one inverter (L1) (how can that happen, with connected grid)
few days later,
- "BMS Internal Error Alarm: Alarm" (and batteries dont charge any more)
persistent, followed by
- Low Battery Alarm (no wonder, batteries are eventually depleted)
- VE.Bus Error: VE.Bus Error 8: Ground relay test failed
and since, the system is in error state, and not working.
Batteries eventually switched off, unpowering their hub (as it is run from the 48V), so now, no battery pack any more (but that can be seen as normal and to be solved separately)
When set to "on", the Multiplusses try to connect to the Grid, but give up immediately and show a blink code (one different than the two others) which is not explained in the victron app.
I assume that one or two of the Multiplus-II 5kVA devices are broken, but as my provider wants to be paid to check them i rather ask community here for your opinion :)
.. if i set the multiplus-II switch to "I" (charge only), they engage with the grid (you can hear the relay) but then one hums very loud and agressively.
.. if i set the multiplus-II switch to "II", they try to engage with the grid but switch off more or less immediately, i assume with that error 8, and they disturb the grid enough to kick the SMA inverter connected before them off the grid.
Here are 3 short video clips (sorry for the moving camera in video 2, i tried to capture the sound/humming better).
Video 1: Behavior when starting up as charger only: (waiting form mains, should be ok) https://www.dropbox.com/s/0c73jf0xul8nije/Video%2022.07.20%2C%2019%2046%2016.mov?dl=0
Video 2: Behavior/humming when connected as charger: (only #1 is humming) https://www.dropbox.com/s/20e3ebb3fbkg2fi/Video%2022.07.20%2C%2019%2046%2027.mov?dl=0
Video 3: Behavior when having tried to connect in switch setting "On"
Anyone able to diagnose this ?
Thanks for your assistance