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waterskier91 avatar image
waterskier91 asked

Multiplus 2 Ground relay not opening with generator connected

I have a Multiplus 12/3000/120-32 in my car with an RCD on the output.

I have the ground relay turned on in the settings.

I am using my inverter with my Honda EU2000 inverter generator and inverter in the car in power assist, to run my house during blackouts from a recent cyclone.

My understanding was the multiplus's internal ground relay was meant to open when the inverter sees mains power, in this case the generator which is ungrounded.

This isn't happening because my RCD trips as soon as the house DB (with MEN) is connected.

When generator is connected i can send the ground relay off setting from VE config and hear the relay opening.

All works as expected with the ground relay setting off.

So im wondering are there only certain conditions that the ground relay will open with mains connection? will it not open with and ungrounded supply?


Thanks

Multiplus-IIGenerator
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Kevin Windrem answered ·

The ground relay will open a fraction of a second before the AC input relay closes and a fraction of a second after the AC input relay opens. So you may not hear two separate clicks.

Not sure about RCDs but GFCIs here in the US will work whether or not there is ground/neutral connection on its input. In fact, it is the only legal way to connect an appliance with a 3-prong plug to an ungrounded branch circuit (neutral and hot only). This is often done when replacing outlets in old homes that have 2-wire branch circuits.

The fact that the RCD on the output of your Multi is tripping probably indicates there is a fault in the wiring at the Multi's output. A common mistake is connecting the neutral of the multi's output (in this case after the RCD) to the incoming neutral.

You should also bond neutral to safety ground at your generator. You can buy a plug that does this or if you are brave, open up the front panel on the generator and do it inside. I added in internal jumper on my EU2200.

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waterskier91 avatar image waterskier91 commented ·

The issue im having is that it's not opening when the generator is connected, i can hear the relay "click" open when i send the "ground relay off" setting. So its not opening the ground relay when connected.

I have checked/tested all the wiring. If there was a crossed up neutral the RCD would trip all the time. It only trips when connected to the house with MEN a second parallel earth neutral path. If i disconnect the MEN in the house DB (Not legal is Aus) the system works fine.

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Kevin Windrem avatar image Kevin Windrem waterskier91 commented ·

You should verify that the relay is closed with a meter. If the generator has no ground-neutral connection you should see at least several volts between ground and neutral on the output of the Multi with nothing connected to the AC output.

I believe the multiple earthing is the cause of your RCD trip. It doesn't happen with the generator because there is no up-stream G-N bond. With grid power there is an up-stream connection. Someone who is familiar with MEN and your country's electrical codes needs to advise how to resolve this.



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waterskier91 avatar image waterskier91 Kevin Windrem commented ·
Yeah I’m mate I have verified all this. I am an electrician so very familiar with it.

I have proven it’s not opening I was hoping someone from Victron could tell me if it was performing as it should or if my product is faulty

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