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pegasus2009 asked

Correct setting for 2 MultiPlus Inverter outputs

I have 2 MultiPlus 3000 watt units to power my sailboat 50 amp 240 Volt USA type panel, one inverter for each ac line. When inverting the units work about 5 to 10 minutes and then have a synchronization/timing error. It does this using only single phase 120 volt appliances on each output line or using two phases such as the 240 volt hot water heater. I am not exceeding over 2000 watts on either inverter line. Current setting is for Dual Phase 180. L2 Floating with return to original phase. I have 3 x 300 amphour VIctron lithium batteries for the DC source and 1200 watts of solar inputing through 3 Victron MPPT units.

Should I change the L2 setting to Fixed or L2 Floating only without return to original phase?

multiplus in parallel
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2 Answers
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mt-geek answered ·


The two inverter outputs neutral need to be connected together then connected to the breaker panel neutral. the amperage is measured on the neutral side

https://www.victronenergy.com/upload/documents/Split-Phase-Quattro-system-with-Cerbo-GX-Touch-50-Discover-42-48-6650-Smart-solar-MPPT's.pdf

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pegasus2009 answered ·

Both neutrals are tied together at the breaker box. This is a marine style box so there is only one neutral bar for the entire box and one ground bar. My boat came with the ground bar and the neutral bar bonded together in the box. Original schematics show these bonded together at the box as well. I know many boats are not but this one is.

Marine style breakers do not plug into a bus bar as a home unit does. They remain separated with each breaker having a wire screw for Line and a wire screw for Load. L1 and L2 come into the box and breakers on L1 are daisy chained together and L2 breakers are on a separate daisy chain. The daisy chain runs directly from the line in screws of each breaker.

When I originally installed the inverters the Victron installer tried to separate the ground and neutral bonding in the breaker box. Some of the breakers would work but most would click off if any current was used.

The Victron installer also originally had the shore power and generator power "passing through" the Multiplus units. But just after he left the timing problem began. Turn on a microwave or small appliance and after 5 or 10 minutes the E 10 timing error or E 3 system error would kick the system off. Have to reboot everything. The Multiplus was doing nothing but passing through power but continuously kick off. So I changed it to where I can use the battery charge function and inverter only when I physically turn them on with the MultiControl. No more pass through power. This saves battery power as well as the units are not on all the time at shore or at anchor. I can now cook on shore power or generator power without constant shut down.

I had the Multiplus units "professionally installed". I did some of the battery cable wiring and ran most of the cables (all supplied by Victron) myself. But the Victron guy checked everything before any power was ever turned on. I followed an example on the Victron website that was almost identical to my situation. He said he could not have done it better. Now the installer won't come back even though I started asking the day after he programmed the system, because he said I wired it. Now it has been 6 months of having to run the generator and forget about using the inverters. They just don't work. He programmed it he checked it and approved it but I am stuck with $20K of unusable equipment at this point. I have 900 amp hours of lithium batteries for nothing. At least I have some fancy battery chargers that I never need since the inverters don't work and the solar panels keep the batteries charged anyway.

Can someone please help. I will be happy to be shown where I missed the boat. If anyone knows someone to help in Ensenada please let me know.

Thanks.

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mt-geek avatar image mt-geek commented ·

Do you have a mk2 or mk3.

Sometimes the cat5 cable between the inverter get bad. If you have a new one try replacing it.

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Kevin Windrem avatar image Kevin Windrem commented ·

The breaker tripping when the safety ground and neutral are isolated should be investigated.

Make sure safety ground are not connected anywhere since your shore power connection will bond these two together at the service entrance.

Make sure no loads return to the safety ground bus. Load neutrals should connect to the GFCI breaker neutral lug or directly to the neutral bus if the breaker is not a GFCI.

Measure the voltage between the safety ground and neutral busses in your distro panel. Anything more than say 10 volts as you switch on loads indicates the neutral is floating and could explain why breakers are tripping.

Make sure the Multis are programmed to NOT disable the ground relay. When the Multis are inverting (not pass-thru or assist), the AC input is isolated along with the neutral to safety ground bond, so the Multis need to make this connection internally.

Make sure the Multi input neutrals are not connected to the Multi output neutrals. Of course, the input neutrals SHOULD be connected together. Ditto for the output neutrals. Connecting them to the same neutral in the distro panel should be sufficient.

If you have a bypass switch to route AC around the Multis, make sure you are also switching the neutral. Otherwise, the input and output neutrals will be connected OR the output neutral could be floating. Neither is good.

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