I have a 2 multiplus 12volt 3000va split phase, autotrasformer and 12kw standby generator. Everything works fine until my 240v well pump kicks on when the gen is running. When the gen is on L1 is charging the batteries around 1800 watts and L2 is around -1200. I have no clue why. Any help would be greatly appreciated. See attached pics
Welcome!
Please confirm/answer:
- You have 2x Multplus 120V 3000 VA configured for split phase.
- Is the autotransformer configured to balance the loads evenly between the two Multipluses?
- Are the neutrals of the Multipluses connected together?
- Are the neutrals of the Multipluses connected to anything else?
- Is the generator split-phase 120/240V (assuming yes).
- If so, is the generator neutral connected to the Multiplus neutrals?
- Is there a neutral-ground bond in the generator?
- Do you have a second neutral-ground bond in a panel?
- Is the autotransformer neutral completely isolated from the multiplus neutrals (even through a ground path)?
I’m speculating that the autotransformer neutral is connected to the generator neutral either directly, or indirectly through ground. This puts the AT coil in parallel with the generator coil, and current is flowing back.
Thank you for the quick reply.
The multiples are set up in split phased wired to the Auto transformer, then from the auto transformer to my home breaker panel. The only reason I have it wired like that is because I originally had only one multiplus wired to the Auto transformer so I could run my well pump.
I got a second multiplus I just wasn’t sure the best way to wire it, weather stacking them or split phase. I don’t have a problem stacking them then running it through the auto transformer to get my split phase. I just don’t know what the best way to go about it is. I have a Winco 12kw stand by generator that 120/240. The generator is wired to a small breaker panel (not the
Whole house panel).Then from the breaker panel it goes to the multi plus for the chargers. I’m completely off grid. The home breaker panel and everything I have wired as a regular house set up. I don’t know if any of that makes sense. If you’re in the state, it might just be easier to talk over the phone. If so, my number is xxx-xxx-xxxx. When i get a chance, I’ll draw up a sketch of everything and how it’s wired.
Post edited to remove phone number due to spammers, per community rules.
A wiring diagram is the best way to look at the issue, keeping careful track of where neutrals and grounds are connected.
Ok perfect. Do you think 2 multiplus in spilt phase going to the auto transformer is the best way to go or set up the 2 multiplus in parallel then going to the auto transformer to get split phase? Only thing 240 I’m running is a 8amp 3/4hp well pump.
I think having two Multipluses configured for split-phase 120/240V is the way to go.
The role of the autotransformer should only be to balance the loads between the inverters.
And in a pinch, you could remove the autotransformer, and still have a functioning system.
This is how I have my own dual 48V 5k Quattros configured here.
I also have a 3/4 hp well pump.
Using the AT as an up-converter would greatly limit available power, so I do not recommend parallel Multipluses at 120V to up-convert to 120/240V with the AT.
Ok that’s what I thought. You don’t happen to have wire diagram for your setup by chance? This is the diagram I Been using. I’m not sure how accurate it is. It’s not from Victron website. I can’t find one on there site exactly for what I want to do. I called local dealers and no one wants to help.
Take a look at this stacked split-phase Quattro balancing setup with an autotransformer.
You can ignore the second input on the Quattros, as the Multipluses only have one input.
Notice how the output Neutrals only go to each other, and nowhere else.
In the graphic they show them spliced inside the autotransformer but not connected to it.
Notice how the input Neutrals are combined and also go to the generator neutral.
Notice how the ground relays in the Quattros are disabled, but they are wired to control the AT ground relay.
I find the block diagram to be helpful:
What they don’t tell you is that there cannot be a Neutral-Ground bond in the generator.
If there is, the neutral current will flow on the ground line (“Objectionable current”).
If I were you, I would not use any of the ground relays, and would put one Neutral-Ground bond in your breaker panel. There should only be one at all times, and that location makes the most sense.
Ok I think I understand now. My gen Runs to a sub panel. Then from the sub panel L1 hot neutral ground go to one multi then L2 hot neutral ground go to the second multi. Both neutral going out are connect to the bus bar in the sub panel and ground is wired the same to the bus bar in the sub panel. The double 30 amp breaker on the right goes to the multi IN and the 50 amp breaker on the left is where the gen comes into the sub panel. I have the AT wired the same as the diagram. I did not change any relays on the AT or the Multi. Also attached is the gen wire diagram.
OK, that is pretty straightforward, thanks for the pictures.
I do not see a Neutral-Ground bond in the generator schematics (there may still be a bond wire internally, but maybe not).
I do not see a bond from Neutral to Ground in the sub panel, unless there is a hidden green screw somewhere not in the photo. Good.
In the main panel with your circuits (not the sub panel), see if there is a green screw bonding the neutral bus to ground.
The default behavior of the Multipluses is to enable the ground relay only when inverting. You should check to see how that is set, either in VictronConnect or VEConfigure with an MK3 USB dongle. Don’t change anything yet.
Sorry for the delay in response. Here’s a better picture of that subpanel. The main breaker panel for the house is wired the same way. I just remembered that none of the devices/breaker panel/Generator/etc. are grounded. I have the ground rods in the ground. I just forgot I gotta wire them up… I wasn’t quite sure the best way to do it and what size wire. I noticed when the inverters are in assist mode it doesn’t backfeed. attached are a couple pictures of the breaker panel and the screenshot of the display when assist mode.
Ground rod electrodes are normally wired to the ground bus bar with bare AWG 6 or AWG 4 wire per code. You only need AWG 4 if the bare copper is exposed to potential damage. This should not have any effect on your issue, though it is a safety concern.
Not sure what to make of that.
Can you confirm the current Multiplus Ground Relay settings (on both units)?