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exmoso avatar image
exmoso asked

Multiplus II 2x120 generator compatibility.

What is the condition that the Multiplus II 2x120 uses to determine its power flow as described in the Data sheet? Or whether the AC input is 120v or 120v/240v split phase?

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In the case of the Multiplus II 2x120, when you connect the inverter in-between the automatic transfer switch and the RV panel the 120v/240v input connection works as intended and a 120v input connection also works as intended. Unfortunately it seems that the Multiplus does not pass through both lines from industry standard generators. screenshot-10.png

I believe the problem is that a lot of RV and off grid generators only output 120v. Most of them such as the Cummings Onan- 5.5HGJAB-6755L which is rated for 5500watts or 45+amps has two outputs. Each is 120v and outputs about 23amps. In most cases it is not possible to combine L1 and L2 out of the generator as the two lines are out of phase, not 180° out which would give you 240v but 120°. Meaning you can't combine the 2 lines to get the full 5500watts or 45+amps single phase to the Multiplus. Probably a cost savings thing on the part of the generator manufacturer as they can use the same components across multiple generator configurations. Either way this is common place in the industry here in the US.


So my question is, can the Multiplus II 2x120 be configured to detect this power type and passthrough both legs? If the Multiplus is actually detecting the phase and not just 240volts then there should be reason to believe Victron could remedy this with a firmware update. Correct? Also, if the voltage between L1 and L2 is 208v would that be an easier setting than the phase detection?


Multiplus-IIGeneratorsplit phasemulti phase
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exmoso avatar image exmoso commented ·
BUMP
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5 Answers
Rob Duthie avatar image
Rob Duthie answered ·

Hi

Are going to use 2x multiplus2 inverters for split phase? If you do you can set using VE Bus System Config to make the inverters split phase with L2 floating so it shifts from 120 to 180 phase shifting dependin on the input .

Regards

Rob D

NZ

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exmoso avatar image exmoso commented ·
Hey Rob,


The Multiplus II "2x120" is a single 3000w inverter that has the ability to passthrough 50amps of 120v/240v split phase. Which is a common power format in north America.


I am aware of the capability you are mentioning, multiple inverters into a split phase with a floating phase. Which makes me hopeful that the Multiplus II 2x120 can in fact detect phase differences and can be configured to passthrough the 2 lines 120° out of phase.

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ssilverado60 avatar image
ssilverado60 answered ·

I have a new install on my trailer and am having the same issue. Is there any chance a firmware update will come in the future to allow us to use both legs of our generator when using it?


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exmoso avatar image exmoso commented ·

Could you put a multimeter on your generator output while its running and see if there is a voltage between line 1 and line 2? The red and black wire.

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sac-rv avatar image
sac-rv answered ·

I was just watching this video last night on the very same subject. He had an interesting work-around.


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Caza Gomis avatar image
Caza Gomis answered ·

The MultiPlus ll 2x120 can do standard split-phase 120/240VAC, with 180 deg phase angle between L1 and L2 input. This is commonly 240V exactly.

This can range to 180-280VAC between L1 and L2. This is approx. a 120 deg phase angle of 120V lines , which is two legs of a 3ph supply, but accommodates for individual line voltages in the range of 90-140VAC.

If the MP 2x120 senses only 90-140VAC on input, it will only allow L1 to connect (The min/max input is adjustable to a finer range with software), as this is considered a 1ph supply voltage range.

The blocking of L2 when a 1ph supply voltage range is detected is intentional, as the MP 2x120 measures the phase shift in order to calculate the current passing through the neutral.

When the phases are in sync, this can no longer be measured, which could potentially be dangerous, as more current could pass through the unit than it was designed to handle.

Theoretically, allowing in phase lines to pass through the MP 2x120 could be possible through a software update, but only if there can be a guarantee that the unit would not see current above what the relays and internal wiring are designed to handle.

Victron does not seem to have a solution at this time, but they are aware of the issue here and brainstorming ways to resolve this.

Best,

Caza G.

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alaskannoob avatar image
alaskannoob answered ·

I have a Honda EU7000 that has a 230v output and requires a plug that takes two hots, one neutral, and one ground.

I have two MPII 48/8000s that I'm going to set up in parallel and would like to wire the generator to them to supply power in an off grid setup. The AC-IN of each inverter only has three inputs, a hot, a ground, and a neutral.

Since I have two inverters, could I wire the cable to provide power from the generator to the inverters?

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