3-phase system trip AC-IN on switching from battery

DIY
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1

System is configured and running on battery without issue. As soon as 3-phases AC-IN is turn on and 3x Multisplus II (48/3000/35-32) detects it and want to switch on AC-IN my RCD (type AC, 0,03A) trips.

All AC-IN are coming from same 5-wire cable L1,L2,L3,N,PE, the only non-standard thing is that each Phase is protected with RCD type AC on each line (I didn’t want to have issue when something trip off RCD and cut off entire floor).

On AC-OUT1 side I have nothing on L1, one outlet on L2 (300W), one outlet on L3 (nothing connected).

DC cables are same length, but I dont think the issue is on DC side as inverter mode works fine.
AC cables are same length, and they are very close to distribution board each about ~1m - 1,5m
All 3 RCDs are tested and working correct.

Why this is happening and what should I do to fix it ? Replace 3RCD to 1 RCD ? change type of RCD ?

2

As you rejoin the ‘N’ conductor behind the multis … you MUST use a 4-pole. RCD at the input. 2 of the 3 2-pole RCDs will always trip.

1 Like
3

I replaced cable on input side with same batch/type/lenght.

So I should replace 3x 2-pole RCD to 1x 4-pole RCD, I can try that.

4

Yes … will work :+1:

In the event of a fault in the Multi network, all multis switch off anyway

5

That I know. Looks like I need to make a trip for RCD, but it would be splendid if this would help.

So if I start to understand now, the moment Multis want to bypass battery and use AC-IN on all multis it acts as System was 3-phase, so they join Neutral on all Multis ?

I did connect AC-Out1 N with all the Multis to one line but I would not think that from AC-IN site it would act that way.

I was also thinking that Multi “throw” error in a way that RCD would trip so no future damage to installation/machines would be done.

Fingers crossed that RCD will do the job.

6

Thank you so much! All fine !

7

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