Hi guys, I am planning to use 1 Multiplus II 5000VA AC-coupled with Fronius Primo 4.0 on phase L1 on a 3-phase grid powered system. My question is: if there are some issues with 3-phase loads like a Heat Pump, when suddenly happens phase L1 grid failure and then Multiplus will work on inverter mode, although L2, L3 still powered from the grid?
Hi @pkorkas
3Phase loads should not be connected in anyway to the essential ac-out of the 1ph multiplus arrangement that you described above.
Only if you have a 3 x Multiplus arrangement this can be done.
Best regards
Riaan
Hi @Riaan Barkhuizen. Thank you for your reply. So on the above arrangement I must exclude all 3-phases loads from multiplus output even when it works on bypass mode?
Correct. If you have an energy meter as part of the system you can still have solar energy supplied on one phase, which would create some energy savings. Please don't connect anything downstream of the 1 x Multi arrangement. As mentioned before there would be no problem if you had 3 x multi setup.
If multiplus is working in bypass mode, there should be no problem with 3-phase loads.
But if you want to use the multiplus as a source of missing grid phase it will not work, because the phase supplied by multiplus will not be synchronized with the other 2 phases.
In 3-phase system, phases are 120 deg. apart, and multiplus has no clue where are the other phases in terms of phase position.
Only 3 multipluses properly connected and set-up can provide a proper 3-phase system when grid is missing one or two or all phases.
