Two MultiPlus-II in parallel with external transfer switch problem

[Joel (Joel Nordahl)]

Just setup two MP II 48/8000-110 in parallel with external transfer switch according to the documentation. External transfer switch

According to the manual ac input should not be connected to the slave.

When I test it they run fine in inverter mode. But when I connect ac in the external switch connects and then disconnects and I get the error “#19 slave does not have ac input”.

They are both loaded with the xxxxxxx-S99 firmarware. The only thing I can find is that the configuration in VE.bus system configuration is that I can’t add the slave to group 2 as described in the manual. See attached photos.

What could be the fault?

I have done several installations without this fault but this is the first time I’ve done it with MultiPlus II.

Thanks for the help,

Joel

[DuivertNL (Marc)]

Where in the manual does it says ac in should not be connected to slave?

[Joel (Joel Nordahl)]

In 3.1.2 “For paralleled units, connect only the master unit (of each phase) to the AC-IN terminal and leave the slave units’ AC-IN terminals unconnected.”

and under troubbleshooting

“Check whether the AC-In terminals on slave units are wired. They should not be wired”

[Joel (Joel Nordahl)]

Ok, so problem solved, in a way.

Apparently you can’t run two MP with only one phase and external transfer switch. Three phase is ok but not single phase.

So then the only option if I want to run singel phase on 8kW and up is to use quattro.

It would be good if this makes it’s way into the manual for running MP with external transfer switch.

[lxonline (LX)]

@Joel

I have done several installations without this fault but this is the first time I’ve done it with MultiPlus II.

With the external transfer switch application in single phase/parallel with other models?

Manuals usually define intended use, not every conceivable way it cant be used.

All the schematics and illustrations for use cases show three phases in the external transfer seitch manual. Including the walkthrough for configuration which you posted the picture from.