How much is the short circuit current in an off-grid system using (genset + PV)?

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dawiddebinski asked Jan 12, '24

How much is the short circuit current in an off-grid system using (genset + PV)?

I am designing a single-phase off-grid system using Quattro II 48/5000/70-50. The system connects using Cerbo GX single-phase generator (AC-IN1), two MPPT 250/100 Tr and 3x 48V 230 Ah batteries. I implement the output through AC-OUT1, I can get a maximum output current of 21A from the Quattro II and 40A from the genset, totaling about 60A.

In the output switchgear I use various overcurrent protections including "C" chrakteristics. Of course, they will work on overloads, but in order for them to work on a short circuit it is absolutely necessary to know the value of the short-circuit current in the off-grid system.

I am interested in the condition when the only source would be the Quattro II, the energy storage is charged, and the genset is not working.

Where can I find such information? If it is, for example, 80 A, with the "C" characteristic, the current rating of the protection would have to be less than 8 A, and since the output I have the ability to load the output to about 60 A, I would like to take advantage of this.

MultiPlus Quattro Inverter Charger

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Answer 1 · 2024-01-14T02:55:26Z

Paul B answered · Jan 14 at 02:55 AM

the max overload is double its ratting so for a few secs you maybe would get about 42 amps being 10000/220=45 amps

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Answer 2 · 2024-01-14T04:32:05Z

JohnC answered · Jan 14 at 04:32 AM

@dawiddebinski

For what it's worth, Victron actually provided the breakers onboard the Easysolar series I (not II). For the 5000 model (Multi[lus based) they used 63A (Chint NL1-63) for ACOut1, and from memory just a simple 16A breaker on ACOut2.

ACIn was a double-pole 63A, but I think that model had a 100A transfer switch.

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Answer 3 · 2024-01-15T09:52:24Z

dawiddebinski answered · Jan 15 at 09:52 AM

Thank you for your response @Paul B and @JohnC

What I am wondering, is how big the rated current of the protection can be in terms of short-circuit current in the consumer switchgear fed from AC-OUT1 (required shutdown in 400 ms). That's why I'm looking for information about the expected short circuit current.

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