POwMR earth issue

[hazlad24]

Hi

I'll keep this basic but can add more to the post if needed. I've got a powmr 6kw inverter and It's powering my garage electrics. I've connected all the earth wires, and it has a 240v feed from the house fuse box. When the battery has power, it will invert the DC and power all my lights and sockets. I've tried to add my boiler circuit to it but the boiler gets an earth error and won't start. I've tested all sockets in the garage and they show no earth! But when I disconnect battery power and the inverter switches to AC input everything works fine in regards to the Earth, the tester shows good earth and the boiler fires up!

Is this due to fact its a cheap nasty inverter? Im tempted to replace with Vitron but dont want to waste money if they function similar with Earthing.


Also, another question, If you exceed the 6kw the whole power shuts off, I assumed it would either switch over to the AC input or draw additional current from the AC input to compensate? Temped to get a 5kw victron multiplus but if i exceed 5kw will that also overload and shut off all power?

cheers

 

[Supervstech]

Odd.
Perhaps youdo not have the invweter grounded to the same location?

 

[hazlad24]

I have a 10mm earth from the house fuse box connected to AC in, on inverter then a 16mm live and 16mm neutral connected to AC in from house fuse box via 50amp breaker

 

[anschluss]

Hi

I'll keep this basic but can add more to the post if needed. I've got a PowMr 6kW inverter and It's powering my garage electrics. I've connected all the earth wires, and it has a 240v feed from the house fuse box. When the battery has power, it will invert the DC and power all my lights and sockets. I've tried to add my boiler circuit to it but the boiler gets an earth error and won't start. I've tested all sockets in the garage and they show no earth! But when I disconnect battery power and the inverter switches to AC input everything works fine in regards to the Earth, the tester shows good earth and the boiler fires up!

Is this due to fact its a cheap nasty inverter? Im tempted to replace with Victron but don't want to waste money if they function similar with Earthing.

The effect you describe probably stems from the lack of a neutral-earth bond when the inverter is in battery mode. When the inverter switches to grid bypass, the earth is considered "good" because it is bonded properly to the neutral: The TN-C-S earthing system commonly used in the UK ensures that there is no potential difference between neutral and earth. This keeps the boiler happy.

However, in battery mode, the input line is disconnected, the AC output becomes "floating", and the neutral has no reference to earth. This makes the boiler unhappy.

The main problem with the cheap Chinese inverter is that many of them apparently seem to turn a blind eye to the earth-neutral bonding when in battery mode. Since this type of inverter does not internally connect the neutral to earth when in battery mode, an additional relay could be added. This would create the necessary bond between neutral and earth. The challenge is that you need to detect in which mode the inverter is running, since it must only create the neutral-earth bond when in battery mode.

I don't own a Victron Inverter, but I am pretty sure this is one of the features that sets it apart from the cheap inverters: There is a internal neutral-ground bond relay that engages automatically when there is no external AC, as confirmed by the manual for the Multiplus II inverter:

Victron Multiplus manual

This product is provided with a ground relay (relay H, see appendix B) that automatically connects theNeutral output to the chassis if no external AC supply is available. If an external AC supply is provided, the ground relay H will open before the input safety relay closes. This ensures the correct operation of an earth leakage circuit breaker that is connected to the output.

So yes, in a way, replacing the "nasty" inverter with a Multiplus would most probably solve this particular problem (in the event that my remote analysis is correct...).

 

[mikefitz]

due to fact its a cheap nasty inverter

Yes.
The Victron has a built in neutral bonding relay, this only activates when on battery power. Where AC Input is available the relay deactivated and the bond is provided by the house main panel/ incoming cable.

If your garage is metal framed and/or some distance from the main dwelling then different regulations may apply to protective earth provision, with the need for a local ground rod and no export of PE connection between main dwelling and remote building.

The Multiplus cannot deliver continuously more power than the rating,

Multiplus-II critical AC-out and overload risks? - Victron Community

community.victronenergy.com

A final point is that with the existing set up, any RCD would fail to function correctly in battery mode due to the absence of the neutral bond.
I am suprised that your installer did not identify the issue at the testing stage .

 

[hazlad24]

Thanks for all the replies guys. I’ve ordered a multi plus 2 5000 and collecting it Monday. I already have a victron shunt and 2 mppt chargers so makes sense to have everything victron