Multiplus II 3-phase setup -- how to detect if one of the Multiplus II inverters is broken

Hello Experts and Professionals,

building a highly available and grid-failure-independent system I am using 3 Multiplus II in a 3-phase setup. The mains (grid) comes in on “AC-IN”… ALL LOADS are on “AC-OUT1”.

The infrastructure:

holds PV via several linked MPPT RS450/200 as well as a LiFePo Battery bank based on ‘Pylontech’ BMS.

There’s also a Emergency-Power-Genset on the “AC-IN” side in order to to achieve the above mentioned goal.

In order to cope with a defect 3-phase Multiplus II setup the infrastructure has a power switch that switches mains (grid) from “AC-IN” to “AC-OUT1”… but only in case the inverter setup is defect beyond recovery.

Challenge: Now in order to reduce the chance of black-outs
I am battling the risk of the Inverter setup to be defect. In particular the system needs to be available EVEN IF the 3-phase Multiplus II setup is defect because one or more inverters are defect.

Yet I am at a loss on how to detect that the MultiPlus II 3-phase system is defect.

Any help on how to detect that the 3-phase MultiPlus II setup is ‘gone’ (defect, non recoverable) will be highly appreciated.

Any questions that are not addressed by the above information I am glad to respond to.

Thank you for looking into this.

Best regards,

homa