Multiplus-II 48/5000 in parallel AC Cabling and MCB/RCBO

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hybridizd asked Sep 28, '23

Multiplus-II 48/5000 in parallel AC Cabling and MCB/RCBO

I am in final stages of setting up 2 x Multiplus II 48/5000 in parallel and just need some advice on wire dimension and MCB/RCBO setup.

I plan to run 10mm2 Twin-Core+Earth from 240VAC Grid/Mains to MCB 50A, 10mm2 Twin-Core+Earth from MCB 50A to each Multiplus 48/5000 to AC-IN (Same cable length and size)

Grid/Mains connection is for backup power and battery charging if required.

Not sure what cable size I should run from each Multiplus AC-Out to a 40A RCBO then to House supply, suggestions welcomed. I do know cable length and size needs to be the same to keep same resistance etc.

Thanks

Multiplus-II multiple inverters

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2 |3000

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Rob Duthie commented · Sep 28, 2023 at 08:13 PM

Hi

With parallel systems smaller wire is better as it has impedance that will have better current sharing than a thicker a cable.

6mm2 will be fine for most situations. Keeping the cable the same lenght is important this appies to the DC side as well.If you read the Victron it will explain why etc. https://www.victronenergy.com/blog/2019/09/03/wiring-unlimited/

Regards

Rob D

NZ

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Modifications Space

Node Red Space

Answer 1 · 2023-09-28T22:13:07Z

sharpener answered · Sep 28, 2023 at 10:13 PM

I take it you are intending that each Multi will have its own breakers.

But a 40A breaker will not enable the maximum pass-through of the Multi 5k, for that you will need 50A and 10 sq mm.

See also section 6.7 of Wiring Unlimited

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2 |3000

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hybridizd commented · Sep 29, 2023 at 04:26 AM

I plan to have a 50A MCB on AC-IN for both Multiplus

the 40A RCBO is for AC-OUT

My calculations show 240V @ 40A is about 9800W peak power. This should be enough? I don't plan to pull anymore power than that through the paralleled 2 x 48/5000W Multiplus units

Guess I can limit the passthrough on each Multiplus to 40A also in VRM

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sharpener hybridizd commented · Sep 29, 2023 at 07:12 AM

Wiring Unlimited says each paralleled inverter should have its own breakers.

I don't recall a VRM setting for pass-through, and from the internal topology I don't know how the inverter could control it other than disconnecting the grid completely or tripping the ACOut breaker.

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