Autotransformer Image


Step up from 120V Fischer Panda pms 4200 fcb generator

I have a Fischer Panda pms 4200 fcb generator 120V and I want to step up to 240V single fase With my Victron Autotransformer. In the manual and wiring examples on the Victron website I sea two wiring examples which are different:




The question is, which diagram is right?

peterdeliefde asked

0 Answers

Off grid inverter setup for split phase


I have build and use small solar system for a while, now that O have build a new house totally off the grid in the middle of the Canadian wilderness, I want to upgrade to a 48v solar based system. As I’m in Canada most of the load is 120vac 60hz except the well pump that will be 240. In addition I have a 240vac generator that I plan to use only to charge the batterie via the inverter/charger

I was thinking to go with 2 multiplus II 120vac 3kva configured in split phase mode and feed each with one leg of the generator. This setup maybe limiting due to imbalance between the 2 inverter

Would it be better to use 240vac multiplus II with a autotransformer? I think that it may be a more flexible option as I could add additional multiplus II in parallel in the futur I need additional power. I’m a bit confused on how to estimate the amp on the neutral of the autotransformer to make sure it doesn't go above 30 amp

rirolarma asked

0 Answers

CerboGX unable to set two way communication

Local or VRM connection to my CerboGX does not have an option to turn on two way communication in settings. I have spent hours researching and am unable to find out why.

latest updates installed on app and hardware.

joe-h asked
tyrone-thomas answered ·

2 Answers

Design of a split phase system 120/240V 60Hz with Victron Quattros

Hi to the community!

We want to build a split phase system 240/240V 60Hz (located in Panama) with Victron Quattros of at least 30kW.

My question is which Quattros I should choose and if an Autotransformer makes sense.

I have to explain what the system should be able to do:
We want to run a wooden dry chamber (theoretic maximum of 20kW) consists of different devices. Most of the time its should not exceed 13kW, but theoretical 20kW are possible for a short term. All devices are 240V/60Hz

Furthermore there will be a small carpenter workshop, with different machines. The machines (all of them are 240V) in the workshop won’t run at the same time. The maximum of one machine is 4kW on 240V.

For the 120V will be the light and maybe small tools like a drill machine, but again, not many machines at the same time. So I think, not more than 1200W.

Initially we wanted to take two of the 15kW Quattros split phase (30kW) but I noticed in the beginning that the 15kW model is only in 240V available. (Later on I noticed in the manual that it is possible to order a model 15kW with 120V, I have to find out if I can get this model).

So I have three options for the topology:

1. Suppose I get the 15kW model with 120V, I would have two of them as a split phase system. I don’t think that I run into a balancing troubles (between the 120V phases), because the heavy loads run on 240V.

2. If I don’t get the Quattro 15kW 120V model, I have to take 4 of the Quattro 8kW models. Two in parallel and split phase. So I would have 32kW power at the maximum. Of course more expensive and more work with AC cable wiring!

3. Suppose I take two of the 15kW 240V Quattros and I will use a Victron Autotransformer (100A) and still most of the most loads are 240V, will the Autotransformer be the right solution? I mean, the Autotransformer makes it possible to use the 240V Quattros and is balancing the two 120V phases (if I understand the function of an Autotransformer in the right way).

The rest of the system (beside the inverters) will be the following:

- 55 kWP module power with a few MPPT RS (I have to do the calculation with the Victron Excel, if I have the data sheet of the modules)

- 176kWh LiFePo4 batteries (15 pieces in parallel with 48V/230Ah connected with copper busbar)

- Lynx system, Cerbo, all connected via VE.Can
- ESS, the system should be capable to feedback electricity if the dry chamber/workshop is not used

- A generator (have to think about the size) if there is a power outage and the batteries will deplete

I am a technical engineer and I build up a three phase system in Austria (3x220/50Hz) with 3xMultis 5kW, 15kWP and a self built LiFePo4 battery (560Ah@48V). So I am new to split phase and electricity in general here in America.

I am happy about your recommendations or comments!


mswoboda asked
shaneyake commented ·

3 Answers

Autotransformer with 120V input

What does the Autotransformer do with the 120V side if the input on the 240V side is 120V?

kev-rm asked
snoobler answered ·

3 Answers

Autotransformer to convert shore 230v shorepower to two 120v/120v

I have read several posts on this topic and I am still confused. I have a sailboat with US shore power inlet (2 x 120v). I am adding an european 230v shore power inlet for when I go to an european 230v 50hz marina. I would like to step down the 230v inlet to 2 x 120v (L1 & L2). My question is: having already a galvanic isolator installed for the ground wire, and assuming frequency (50 or 60hz) is not an issue for me, can the Victron Autotransformer accomplish this?

luigi-miranda asked
luigi-miranda commented ·

2 Answers

MP II + 3 phase converter transformer VS 3xMP in 3phase wiring + phase converter transformer ?

Hi. I have a small farm in which I have various pumps, biggest one for now is 4.5Kw. I also have a house nearby and I'm considering getting a solar system given the provoked .....Erm, sorry I mean the current energy crisis... :) Anyway, all the pumps are 3 phase, the house is single phase. My initial thoughts were to get 3 Multipluses 3000 48 and set them in 3 phase, but then I remembered that I'd have to be very carefull because of a water heater and oven in the house, that together surely surpass the MP's 2400W rating. Now I found about 2 companies that sell transformers to the industry and they have 3phase to 1 phase converter tranformers and also vice versa!! For 5Kw those things weight more than 50Kgs !! But they cost about 2/3 of a single new MP.

The other option , which I'm pending to right now, is to get a single higher wattage MP (i.e. the 8000 48 version or even the 10000, although that is probably overkill and has too much losses for my taste, was thinking of minimizing the battery size for now) and put a single to 3 phase converter transformer in the circuit for the pumps.

Question is, which one would be preferable ? I know using transformers to make the conversion, one way or another, is going to incur in losses, does anyone have any experience with this ? The companies do provide a datasheet but they don't include the efficiency and why should I trust them for that anyway, the efficiencies for transformers are probably known in general.... Here is a link with an example:

Going with a single MP would be better in terms of future maintenance / repairs / replacement (although this shouldn't be a factor with Victron, given the higher quality, but eventually anything can die), given that if I have 3 MP wired for 3 phase and one of them goes wrong, I'd have to find a replacement with exactly the same model, whereas with a single bigger one I could borrow one / have a spare / more easily...

One advantage however if I go the path of 3MP wired in 3 phase is if one inverter malfunctions I would
still have the other two to feed the single phase circuits in the house, and could even wire it in parallel with the other one.

Decisions ....

But yeah, I'd like to know the potential transformer losses of the phase converter transformers and if anyone has any experience with this...

Also, another option would be 3 MPs wired for 3 phase and a separate MP for the house, no transformer losses then, although it's more expensive... In this case I could also go with smaller MPs for the 3 phase wiring...

What do you guys suggest ?

Thanks a lot!

jven asked
jven edited ·

2 Answers

Using AutoTransformer to create 120v/240v split phase from single phase 120v input

I have a use-case for the AutoTransformer that is different from what I see generally discussed. I want to use it in my RV to take in 120v 60 Hz from either my Onan Generator (2 separate 120v legs that are SAME phase) or the shore power inlet (30/15 Amp which are 120v 60Hz single phase). I have those 2 inputs going to an automatic transfer switch so whichever one is "on" will pass through to the AutoTransformer. I would like for the AutoTransformer to step up the voltage from 120v single phase to 120v/240v split phase. I will then pass that split phase into the input side of my dual inverters (one inverter for each 120v leg) so that when I have a single leg input, I still get both inverters charging instead of one side passing through voltage and the other rejecting the phase and inverting to make the "correct" phase.

So, my question is, how should this be wired up to the inverter. It has labeled "input" and "output" sides but the "input" side only has 240v Line and Neutral labeled connectors. The "output" side has 120v Line 1, Neutral, 120v Line 2 connectors.

My intuition tells me to disregard the input/output labeling and connect my source 120v power with:

source 120v Line > AutoTransformer "output" Neutral

source Neutral > AutoTransformer "output" 120v Line 1

Then my output would be the 240v wave form stepped up via transformer as measured between the "input" Neutral and "input 240v Line connectors. I would need to carry over the neutral from the other side to provide 120v/240v split phase.

It is this last part I am unsure of and need some guidance on.


Diagram attached of my planned whole system that hopefully makes clear what I am trying to achieve.


cookinwitdiesel asked
Greg Melton answered ·

3 Answers



I am having some problems connecting an Easy Solar with a autotransformer (100A).

The main problem is when I try to feed the autotransformer with the Easy in position 1. a Message appears in the screen that says "Overload" and the Easy turns Off, even with the load unplug.

any idea why is this happening?

Harold Lopez asked
Harold Lopez commented ·

1 Answer

HOW DO I: 120V Single Phase --> 120/240V Split Phase ??

I need to go from 120V Single Phase (either 15A or 30A depending on the source), to 120/240V Split Phase. My inverter charger has both L1 and L2 available so I'm assuming L2 isn't optional.

I'm assuming a single AutoTransformer will step up 120V single phase into 240V single phase, not split phase....but if I'm wrong, then all my problems are solved!

My questions are:

- can a second autotransformer turn 240V Single Phase into 120/240 Split Phase?

- can a single AutoTransformer be modified to go straight from 120V single to 120/240 split?

- is there another device I should be looking at entirely?

Thanks community! I don't know why this specific answer is so hard to find.

dothedr3w asked
dothedr3w edited ·

2 Answers

easyplus transfer current vs easyplus ii


I'm about to buy an easyplus / easyplus ii 48/5000...

I note one difference which intrigued me. The "old" easyplus has a 100A transfer switch vs the 50A of the Easyplus ii

is that correct? what's the reason for this? Does this mean that I should go for the "old" easyplus if I want a smooth experience where any ramp up in demand (e.g. electric oven) is handled without any potential gotchas?

londonflatthing asked
Guy Stewart (Victron Community Manager) answered ·

1 Answer

Autotransformer for Boat application - not getting correct L1/L2 voltage

I have a USA boat with 2 line 120V/230V and now the boat is in Australia.

I fitted a autotransformer so I can input 240v to convert to 2 x 120v .

I have attached the drawing my wiring.

The problem is on shore power I'm getting 240V on line 1 (should be 120V) and getting 120V on the white neutral wire (should be 0V) and the red, L2 0 volts (should be 120V) between the ground bus bar and the same reading between the white bus bar.

If I turn the generator on the system operates normally. all the voltage reading are below.

This wiring is uncommon and I have to wait over 3 months for a technician just to come have a look, so hoping someone might have the answers for me.

I found the problem after my Freezer stopped working, its 120V and with a multi meter had 240V on line 1 and 120V on the neutral.

Shore Power.pdf

marc-jackson asked
marc-jackson commented ·

1 Answer

Multiplus Ground Relay Voltage

I am troubleshooting the ground relay function. I have two multi plus II’s and an autotransformer. The autotransformer is not bonding neutral to ground when inverting, even though I have the ground relay wiring in the place and the ground relay option unchecked in the multi plus configuration. If I put a multimeter in the ground relay on the multi plus what should I read? Also what voltage range / amps can I supply the auto transformer to force the neutral to PE bond.... trying to isolate the problem....

fagan1 asked
ewbcvec answered ·

3 Answers

Multiplus shuts down when trying to use Air Conditioner 24/2000/50

Hey all,

I just setup my Multiplus 24/2000/50 Compact and all seems to be working fine until I tried to turn on my AC.

while leaving the Multiplus in “on” position and plugged into 30amp shore power I turned my AC on and the surge when the compressor turned on made the multi shut down.

I have had my rig parked in the same place for the last 4 months and have had to run my Air con a few times before I setup the Multiplus.

I also tried to run it while my generator was running and that didn’t work either. But I used to run my Air Con off the generator no problem before.

I do have to switch on the “weak AC” setting to get the generator to work but still won’t allow the Air Con to work.

Should I be running the multi on “pass through”? (not sure how to set that yet)

Do I have something wrong in the settings?

does the Victron only allow me to use 2000 watts when I am connected to shore power? (Doesn’t make sense to me)

My generator is 4000 watts and still doesn’t let it happen.

I tried it with everything in the rig off except the Air Con and it still didn’t work.

I am running a 24/2000/50 multiplus compact and a 24 volt 206ah prismatic battery set from LYNX batteries out of Washington state. The battery connections use 4awg wire. Battery is rougly 2 foot away from the multi.

Is the only way to make this happen is to get a soft start for the air con?

journeyoutloud asked
aaronca250f answered ·

5 Answers

100A autotransformer hot without load


I have just installed Quaddro 15kW 230V and I have 100A autotransformer on the output to convert 230V to split phase 120V for my house. I connected inverter and tuning batteries for a while and connected autotransformer input to inverter output, but I haven't connected autotransformer output yet (there is a bypass switch) so there is no load. I left it overnight and today morning I found that temperature LED is on and transformer body quite warm (not hot though). Is there a problem that there is no load connected or I have faulty autotransformer?

rglory asked
Kevin Windrem answered ·

1 Answer


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