I live off grid and have a European Multiplus 230V Inverter paired with an Autotransformer that gives me two 120V legs (I'm in the US). This allows me to use 120VAC in the house and also power some devices that require 240VAC split-phase.
I have a backup generator which outputs split-phase 240VAC. If I want to connect my generator to the Multiplus AC Input, can I simply use one hot wire from my generator as the line and the other hot as the neutral?
Any help appreciated.
Yes, that connection will work and you'd ignore the neutral from the generator.
You may need to adjust some voltages. The generator will output 240 volts and will pass through the Multi to the autotransformer. If that is configured to take in 230 volts and output 120/240 split phase, your voltages running on generator will be high: roughly 125 volts per leg, 250 volts across the legs.
What you should probably do is set the autotransformer for 1:1 and set the Multi to output 240 volts rather than 230.
Thank you, that was my hunch but I wanted to get some external validation.
Yes I'll set the Multi to output 240 instead of 230. I'm unclear on setting the autotransformer for 1:1, can you expand a little more on what that means?
Much appreciated
Transformers often have "taps" for the input and/or output that accommodate different voltages for input and output. For example, 230 volts in 120/240 volts out. Or 100 volts in and 120 volts out. In your case, you want to set it for 240 volts in and 120/240 volts out.
You need to program the Multi to disable the ground relay. This relay connects the Multi's output neutral to safety ground when the AC input is not in use. But you neutral is the center tap between the Multi's two output lines (one of which is normally neutral)
There could also be a problem with an AUTOTRANSFORMER. Some generators bond its neutral to the frame/chassis ground. In your system, this creates a conflict with the system's true safety ground (at the center tap of the transformer). This looks OK on paper however unbalanced loads can create safety ground current which must be avoided.
If you can isolate the generator's neutral from frame/safety ground then the autotransformer should be OK. Otherwise, an ISOLATION transformer would be needed.
An isolation transformer has separate input and output windings so there is no connection between the generator's safety ground and the systems neutral/safety ground
Appreciate your comprehensive reply. I had also been reading up on how to properly setup and wire the Multiplus to the Autotransformer and was aware about disabling the ground relay on the multi. I'll double check and make sure my generator doesn't bond it's neutral to the ground. I know it has a chassis ground but unclear if it's bonds the neutral.
I've been following this schematic from victron and also this tutorial
https://shop.pkys.com/autotransformer.html
This question is years old and is resolved. I had to remove the neutral to ground bond on my generator since the autotransformer already handles that. My Generator puts out 240 with two hots, and both of those can be connected to the 240V Input of my multiplus.
Are you asking because you're having a similar issue/question @AlaskanNoob ?
Yes, somebody pointed me to this thread in my thread question: https://community.victronenergy.com/questions/210650/sanity-check-requested-wiring-honda-7000is-generat.html
I'm about to set up a Honda 7000is generator with 240V output (two hots of 120V each) to a Quattro 48/15000 that is feeding a Victron Autotransformer.
Is your Autotransformer a Victron one? And did you wire a ground connection from your generator to the ground of the AC-IN in your MP, or just the two hots into the MP (leaving out the ground and neutral wires)?
