Multiplus grounding when in charge mode only.

Question

question

logic28 asked May 28, '24

Multiplus grounding when in charge mode only.

The Victron Multi inverter is supposed to lift the internal neutral to ground if connected to the grid however I see from the diagram that all the PE are still connected to the inverter chassis which in turn, being connected to the Grounding bus-bar, would still effectively bond the grid earth to the PV grounding electrode (underground rod)

I want to be able to potentially use the Multi’s charger but I do not want the grid grounding to be linked to my PV ground.

1) Is there a way to do so? Or should I simply lift the grid ground when charging? I expect that would be wrong if using the grid for loads but I would not be, subject to the next question:

2) Can the Multi II charge the battery bank without automatically switching or passing through the grid to my loads?

In other words, can the Multiplus charge and invert simultaneously?

From the instructions below it doesn't seem so but I'm just wondering

Grounding

screenshot-2024-05-28-at-195817.png (215.8 KiB)

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Modifications Space

Node Red Space

Answer 1 · 2024-05-28T19:00:23Z

Justin Cook answered · May 28 at 07:00 PM

No, in "charge only" mode the grid is passed through to loads and used to charge the batteries; the unit cannot invert and charge simultaneously.

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Answer 2 · 2024-05-28T19:14:38Z

Alexandra answered · May 28 at 07:14 PM

If you have grounded centrally and have a NE bond in the DB, then it will grounded anyway?

Why would you want to run an IT network?

https://www.victronenergy.com/media/pg/The_Wiring_Unlimited_book/en/ground,-earth-and-electrical-safety.html#UUID-a7fbe2a9-f339-7955-9305-4df3b1032efb

4

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

flugs commented · May 30 at 06:57 PM

Salut, for the explanation of IT and TN networks, check page 50 of the Wiring unlimited document from Victron:

43562-Wiring_Unlimited-pdf-en.pdf (victronenergy.com)

2 ·

logic28 flugs commented · Jun 01 at 07:44 AM

Ho that IT! In this country that is only used for distribution purposes in this case would it not be more a case of TT rather than IT?

0 ·

logic28 commented · May 30 at 06:13 PM

If you have grounded centrally and have a NE bond in the DB, then it will grounded anyway?
Why would you want to run an IT network?

Hi Alexandra, thank you for your reply however I'm not sure I understand completely your wording.

NE for neutral earth ?

DB for distribution box at the building supply?

Not sure what IT network is referring to

0 ·

logic28 commented · Jun 01 at 06:44 AM

Why would you want to run an IT network?

That is because I am not using the inverter AC input for any loads other than the charger itself so no safety device will be used in conjunction with that line at the installation point whereas the other building still connected to the grid would continue to work as per normal (TN -CS)

If you are familiar with grounding electrode rules you probably know that no two (or more) ground rods must exist in an installation (household) without them being directly bonded.

1) In the event of lightning striking the gradient in the earth could have a potential differential between two grounding electrodes can be as high as 20kV.

2) Furthermore, should the grid's neutral CNE (Combined Neutral & Earth) fail at any point somewhere in the vicinity, any other building in the area would use any copper or metal pipe as their return path to the transformer finding its way back by passing through my earthing cable resulting in a dangerous situation should I disconnect the PE which would now show 230v at that point if any load is active in the neighbourhood affected by the fault.

Basically, I want my off-grid system totally isolated from the grid with the only option of using the grid supply for charging purposes.

0 ·

question