How to wire Multiplus in an IT network

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arildo asked Feb 17, '24

How to wire Multiplus in an IT network

If I got the wring diagram of the Multiplus right, it says that the neutral output terminal is connected to the chassis through a relay, which will open when an external AC source is connected through AC in. Meaning it will be normally closed in an off grid system, and open e.g. when the generator is running.

Now, if I want an IT net I don't want that connection between neutral and earth. How can I avoid it? Not connecting the chassis to earth would not be according to code as this is needed for equipotential bonding.

It would be easy if I can just not connect the PE condutor to the output terminal, but it seems the connection is made internally of the Multiplus. Am I wrong?

system design Grounding

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Answer 1 · 2024-02-17T12:00:27Z

delf67 answered · Feb 17 at 12:00 PM

There is an option in the multiplus settings to inhibit the ground relay when inverting.

ground-relay.jpg (193.8 KiB)

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nickdb ♦♦ commented · Feb 17 at 12:05 PM

That is only for specific use cases where an external relay is going to be used:

Ground relay (see appendix B)

With this relay, the neutral conductor of the AC output is grounded to the chassis when the AC input relays are open. This ensures the correct operation of earth leakage circuit breakers in the AC output.

For specific configurations, such as a split-phase system with an autotransformer, an external ground relay may be necessary. To use an external relay, first, disable the internal ground relay in the MultiPlus settings. For the location of the external ground relay contacts, see Appendix A.

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Answer 2 · 2024-02-17T23:00:28Z

arildo answered · Feb 17 at 11:00 PM

Thanks. That will do the trick.

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