question

nanzikambe avatar image

Existing multiplus parallel setup needs to accomodate 3phase load

Hi! o/

I presently have 2 x 48V 3000 VA Multiplus VICTRON PMP483021010 in parallel connected to a LiPo Freedom Won 20/14 LifeP04 KWh battery working great in an offgrid config (+ victron solar gear charging + genset).

Soon I will need to add two three phase devices as load 400 V AC (+-15%) / 3 ~ max actual 32,6A. In addition I need to accommodate the current maximums allowed by my current setup (<=6000W peak, ~4400W sustained on single phase max ambient temp 40C in summer). The three phase loads will never be used at the same time as the max output of a single phase. This is for a small workshop, it's either or, never both. The three phase loads are large compressor + plasma CNC.

Below are the options I think I have. They are in order of preference by cost:

  • Option 1: add additional Multiplus in parallel allowing sustained ~6600w on a single phase + appropriately sized Variable Frequency Device (VFD) devicre to connect the 3 phase load.
  • Option 2: All Multiplus identical: phase 1: 2 x multiplus, phase 2: 1 x multiplus, phase 3: 1 x multiplus - will this work?
  • Option 3: 3 phase: each phase as single Multiplus 48/3000/50 + additional separate single phase circuit with Multiplus 48/5000/70.

Are any of these options non viable? Are there better options? Ideally option 2 would be 3 phase solution with a single phase using the Multiplus 48/5000/70 + the other 2 phases using my existing Multiplus 48/3000/50s - but I am told should never happen and Bad Things(tm) will happen - and so is excluded for that reason.

Thanks!

Nanzikambe







MultiPlus Quattro Inverter ChargerLithium Batteryoffgridparallel3 phase
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1 Answer
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

HI @Nanzikambe,

Option 1 should be investigated and if supported by the Multi's and the loads, it may be more cost effective.

Option 2 is possible - there are some small issues to how it will report power consumption - but they are mostly cosmetic and reporting - functional power delivery is fine with an extra (identical) unit on one of the phases. Ideally in normal operation you are balancing the different tools across the phases too, even if they are single phase.

Option 3 is non-viable - all units must be identical to sync.

One reason to choose option 2 over option 1 is the inherent balancing advantage of 3 phase on the DC side reducing DC ripple. This might make the difference between overloads when trying to pull a three phase load from a large single phase supply, and smooth operation driving the same load from 3 phase synced inverters.

I would recommend option 2 - but be aware of the increased system complexity - this undertaking is not for the beginner.

If you haven't already, I would STRONGLY recommend that you complete the 3 Phase and Parallel design and installation online training program on Victron Professional.

Also read the Wiring Unlimited manual.

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