Advise about a 3 phase system. What fuses?

DIY
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1

Hi,

I live in the Netherlands. I have a 3 * 25A connection to the grid. I want to make a 3 phase system with these components:
3 * Victron MultiPlus-II 48/5000/70-50
1 * Victron Lynx distributor
1 * Victron Cerbo GX
1 * Victron GX Touch 50
1 * holder for Victron GX Touch 50
3 * Basen green 16S 314Ah batteries

I have a few questions:
Where should I use fuses? I am planning to fuse each battery connected to the victrons. But what fuses should I use? The Mulitplus II is 5000W, so what fuse should I use? If 5000W is the max. what is the calculation for the fuse? P=UI. I want to go to use the range 15% up to 85% SoC. Voltage 20% SoC is 51.2V and 10% is 48V. so 15% is probably (51.2+48)/2=49,6V. 5000W/49.6=100.8A. So should I use a 110A fuse? Or can you give me some advise?
What fuses should I use for in the fuse box? There are 25A fuses before the meter of the electricity company. Should I use a 320A and 50mA (B or C?) earth leakage circuit breaker. Just behind the main switch and SDM630?
I will connect the battery connectiosn of the multiplus devices to each other. How can I connect these devices battery connection to each other? I was planning to make a wire from multiplus 1 to multiplus2, mulitplus 2 to multiplus3, multiplus 2 to battery1. So 3 connections on multiplus 2. Does that fit or should I connect that in another way. I am using 95mm2 wire to connect the batteries. With SC95-8 connections. Victron told me to use cables with max amperage divided to 3. 15000/50=300A. 300/3=100mm2. So 95mm2 should be good. Should I also put a fuse between the multiplus connection that goes to the battery? I don’t think I can connect 3 connection to the multiplus 2? Should I the power in from Victron? Is that not just a very expensive bus bar?
I will use DMX cable to connect the communication lines of the VE bus. I can use the software of the basen green battery housing to limit the voltage up to where battery is charged and is being discharged. Or shouldn’t I do that and let the Victron handle the upper and lower battery limit? I don’t want to use the lower 15% and upper 15%.
This my first system. I am hardware design engineer. So I know something about electronics. Any help or advise is appreciated.
Thanks in advance.

Beste regards,
Mark

2

Hi i suggest you contact a local victron dealer for help with design your system as per community guide lines! An 3 phase setup is not easy!

You have a lot of questions that are also in the manuals

Your planned battery is “unsuported” if it has a compatible bms it will work, but if not it can give you a lot of trouble, if its compatible connect it to the can bus and let the bms control the system

About fusing, recommende fusing is in the manual, fuses need to be in between every multiplus, every battery, and other equipment, you need to use the lynx for that or get/make a busbar

Ofiicialy you are not allowed to have a 20A breaker after a 25A grid supply, but i did that also

Wiring minimum mm2 is in the manual 70mm2 is thick enough for max of 5m, 95mm2 is ok too

Dmx cable is not suitable for ve bus connection! Just use normal ethernet cable

Take a look at some manuals (also available in dutch)

https://www.victronenergy.com/live/battery_compatibility:start

https://www.victronenergy.com/live/ve.bus:manual_parallel_and_three_phase_systems