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David Wickham avatar image
David Wickham asked

120/240 Split Phase on Auto transformer from Multiplus ii 48/5000 70a 230v

Hi everyone,

I need assistance. I would like to produce an output of 120/240vac split phase from the Victron 100a Autotransformer.

I have a Multiplus ii 48/5000 70a 230v. Which terminals do I use to connect the Miltiplus to the autotransformer to produce this this output?

Also what are the terminal to be used on the Autotransformer.

Application-completely off-grid

Multiplus-II
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nesswill avatar image nesswill commented ·

does this help.

Victron Autotransformer wiring for US Split phase: 120VAC to 120/240VAC - Victron Community (victronenergy.com)

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David Wickham avatar image David Wickham nesswill commented ·
Update***

I was able to generate split phase output from the autotransformer. 120/240vac

Thanks everyone for you assistance.

One additional point of discussion.

While taking measurements with my multimeter I noticed that on one leg of the split phase from the autotransformer I'm reading 112vac and on the other leg I'm reading 117vac.

What's responsible for that difference? Shouldn't it be equal across each phase?... like 115vac---0---115vac

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1 Answer
Kevin Windrem avatar image
Kevin Windrem answered ·

Assuming there is no AC input to the Multi, you connect the hot and neutral to the two hots of the autotransformer. The two hots come off the opposite ends of the autotransformer and the center tap becomes the load neutral.

If there is any AC input to the Multi, then you need to consider it's input to insure there is no conflict between the incoming neutral and the load neutral. You'd be OK with a split phase 120/240 volt input but if it was 240 (or 230) volts to neutral then you need isolation between that source and the input to the Multi OR isolation between the Multi output and the split phase loads.

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David Wickham avatar image David Wickham commented ·

Can you share a diagram of the wiring please.. I'm not seeing anything on the victron website for my specific application.

My multi ii produces 230v on L and N on the AC output 1.

I want produce split phase 120/240 safely.

Where do these connections go on the autotransformer. Left terminal block ( 120v- 0v- 120v) or on the right side below the breaker.

I've read that the unit is bidirectional.. seems strange to input from under the breaker of th autotransformer from a 230v supply from the milti.


Any guidance ? Thanks

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klim8skeptic avatar image klim8skeptic ♦ David Wickham commented ·

@David Wickham have a look in the products section, schematics.

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David Wickham avatar image David Wickham klim8skeptic ♦ commented ·
Thanks, i've reviewed it but the Quatro's AC output 1 is different from the Multiplus ii.

I don't see anything specifically for the multiplus ii which has and AC output terminal block of ( L-E -N)

I measured 230Vac across L and N)

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David Wickham avatar image David Wickham klim8skeptic ♦ commented ·

1000027661.jpg

See here

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1000027661.jpg (414.6 KiB)
David Wickham avatar image David Wickham klim8skeptic ♦ commented ·

Update***

I was able to generate split phase output from the autotransformer.

Thanks everyone for you assistance.

One additional point of discussion.

While taking measurements with my multimeter I noticed that on one leg of the split phase from the autotransformer I'm reading 112vac and on the other leg I'm reading 117vac.

What's responsible for that difference? Shouldn't it be equal across each phase?... like 115vac---0---115vac

0 Likes 0 ·