We have two Multiplus II 48/ 5000 installed in parallel and are operating fine except for generator charging. The generator has been wired through a two position switch to run to the ac input of only one of the Multiplus’ in either switch position ( say unit A or B ). This does not seem to work.
Can anyone please confirm if both units need the same ac input to operate in charge ?
Thanks , Chris
One impotant point is the genset need to give a good input signal, so give the Multiplus the possibility to sync with and the one in // who I’m supposing still connected to Grid (and Active).
Xavier
In a parallel configuration all wiring needs to be identical to all units including same length. This includes AC inputs and outputs and the DC connection.
With unequal cable lengths or other resistance differences (your switch), the units will not contribute equally to the overall power.
Parallel systems are discussed in a tutorial on professional.victroncommunity.com and is essential information for a successful design and installation.
1 Like
If you operate a Multiplus II in parallel, the master MP II generates the PWM signal for the slave MP II. So the second MP II is a “lobotomized” add on: it adds to the power electronics, but not the smarts.
Therefore all electrical connections must be shared: they must be the same, but on both input and output AC you need to have some resistance in the cables (by making the cables longer or using thinner cables) to make them work parallel. Since the PWM or charge is excusively determined by the master, the DC part must also be equal connected.
I guess the reason you want to do this is to prevent the generator to be maxed out?
You can limit your input current, and turn on power assist.
However power assist only works from a certain minimal value, and for a MPII 48/5000 this is 6A per MPII, in parallel this makes 12A. So your generator problably needs to be able to push 12A before power assist kicks in.
If you don’t need the feed through or power assist, but just charge the battery, and your generator can’t do that 12A, you might have to look at a third MPII to just feed the battery. That MPII will be independent of the main MPII.
Another thing is: If you really do not need the 10kW for 1 phase but you just need enough power, you might just use 2 independent MPII, or put them in a 180 phase shift. Then you might be able to turn off the “both AC-IN” must be present and use only one AC-IN for charging.
And the last thing is: if your generator is unstable, you need to widen the accepted voltage and frequency ranges and several other parameters.