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radek673 avatar image
radek673 asked

two parallel configured quattros charging batteries from L1 and L2 ?

I've 2x quattroes 8K in parallel configuration (by setting, not wiring)

AC IN/OUT of them are connected/disconnected by contactors following OFF-GRID scenario.

1. when AC OUT => no AC IN from GRID (AC OUT is powering house, taking energy from batteries and FVE panels, AC OUT from both are joined to 1P after 3P contactor - since there are 2, only L1 and L2 is used - its like quattroes => 3P contactor => joined L1, L2, L3)

2. when AC IN from GRID => no AC OUT (just for charging the batteries, 3P contactor is open on AC OUTs)

PLC is driving the contactors and there are mechanical, electrical and software interlocks so they cannot be closed both at same time.

the question: when operating in (2) mode, can I power one quattro from L1 and second from L2 so i can charge the batteries faster and splitting the load into two phases will be also better, since I have 3P GRID and "only" 3x 25A ?


quattro 10kva
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mvas avatar image mvas commented ·

Are you saying ..

  • This is a 3 Phase ( L1, L2, L3 ) Grid / Main Panel
  • There are only two (2) Quattros
  • Grid ON = Quattro #1 is connected to L1 + N for charging battery bank only, No AC Out
  • Grid ON = Quattro #2 is connected to L2 + N for charging battery bank only, No AC Out
  • Grid OFF= Quattros connected in parallel, connected to ALL 3 Phases, in "Single Phase" mode

I think, we need to see an electrical diagram.

I do not know if two Quattros, that are configured for Parallel mode, can charge the same battery bank ( NO AC OUT connections ) from two different Phases L1 & L2. You can try. Will either unit complain = OUT OF PHASE error?

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radek673 avatar image radek673 mvas commented ·

yes, wiring of AC/AC is here https://cloud.uhajicku.cz/s/DgoHS2adnX3JM8s

there are many things :) but the important only for the question are on top

BATTERY CHARGER: L1 connected to 1st quattro AC IN, L2 connected to 2nd quattro AC IN, L3 not connected (reserved for future)

GRID AC IN: 3P main input

FTV AC IN: L1 connected to 1st quattro AC OUT, L2 connected to 2nd quattro AC OUT, L3 not connected (reseved for future)


contactors from left:

1st - closed only in case of 2nd is closed and only if charging is needed

2nd and 3rd - switching main (grid)/quattro (fve) with interlocking and delay

4th - closed only when 3rd is closed to protect L1-L3 join from all sides


I've chosen parallel mode because I know that L1-L3 isnt well balanced in my building and to achieve best results. actually no device in my building requires phase shifting.

the solution can be later easily reconfigured to full 3P system (after buying another quattro).


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3 Answers
Mike Dorsett avatar image
Mike Dorsett answered ·

!@#$??

Ok, so when you are having no mains, the Quatros are in parallel, and your house loads are essentially in single phase.

When mains is on, you have a three phase supply.

for the mains on case: No I don't think that you can charge from L1 and L2 as the inverters will be expecting zero phase shift between the mains phases, and there is 120 degree shift. So there will be trouble as the two quatros try to get in phase with two different phases.

Why not configure the quatros as 2/3 of a three phase system, and NOT parallel the outputs when the mains is off. Yuo then have the problem of which phase to connect the L3 loads to in the mains off condition.

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Kevin Windrem avatar image
Kevin Windrem answered ·

You would need to wire parallel connected Quattros very carefully, matching each connection's length to each Quattro. These connections all need to remain in place while the Quattros are configured for parallel operation. Switching the wiring to support multiple phases REQUIRES reprogramming the Quattros to function as multi-phase units (not as parallel).


If you program the Quattros for parallel operation but don't wire them that way very unpredictable things will happen since the slaves get the same inverter/charger core stimulus as the master regardless of what's connected to the slave.

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radek673 avatar image
radek673 answered ·

ok thx guys for explanation and suggestions... i guess then it will be better to buy one more quattro, go with full 3P system and try to balance the loads ?

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