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lexxloon avatar image
lexxloon asked

Problem with Ground relay Test

Hello, everyone,
I have been running an MPII with a self-made battery together with a Cerbo and a "Smartsolar 250/70" charger for a few months. Everything went without problems so far.

What I did today is I uploaded a new config because I wanted to increase the charging current of the MP to 70A in order to fully charge the battery from the home network. That also worked well.
I have also activated a corresponding charging profile in the Remote Console in the "ESS" area.
After the battery was fully charged today, the MP no longer feeds into the home network. But that has worked great so far. I also have an EM24 in operation.

So after the battery was full due to the MP and the solar charge controller, I uploaded the previous profile again and deactivated the charging profile.
But now that I have switched the MP back on, it no longer inverts from the battery into the home network, although the EM24 correctly indicates that we are currently buying additional electricity from the grid.

I've now tested everything I could check and can't find a solution to the problem.
A fault in the battery can be ruled out. The battery runs great and when I add another inverter to the test, everything runs great.

I don't see any error message either. A single message was displayed on the remote console.
This reads: "Ground relay test failed"
Whenever I turn the MP on and off, it jumps into "charger only" mode
Even if I then manually set it to "On" or "Inverter only", it does not feed into the house network.

Of course I googled it, but couldn't find anything suitable.
Oh, I didn't even connect an AC Out 1 or 2.

I'm hoping for help here, because I really don't know what to do next.

I hope my English is good enough. I helped with Google.

Best regards
Detlef

Multiplus-II
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1 Answer
lexxloon avatar image
lexxloon answered ·

Problem solved:
An unused NYM cable, which is currently lying outside, was uninsulated and got wet in the rain.
After I disconnected it and isolated it accordingly, the MPII starts up normally again.

Regards
Detlef

1 comment
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Warwick Bruce Chapman avatar image Warwick Bruce Chapman commented ·
This is interesting because this ground to neutral fault would have been on the input side of the inverter and in my experience, this only happens on the output side of the inverter.


I could be wrong but this is what I have observed in the field.

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