Victron autotranformer triggers inverter overload

I bought the auto transformer. I tested it with commercial power. I got 2 120v (240).

Everything was good. I hooked up it to my GIANDEL 4000W 24 Volt Heavy Duty Pure Sine Wave Power Inverter DC24V to AC120V w.

I hooked up current monitor on each phase and readings looked good. 2 x 120v.

I wired the transformer into electrical. When i turned on the breaker It immediately sent the inverter into overload status.

When i was reading up on the autotransformer someone mentioned they hooked up a 3000 W to their transformer and it worked fine.

I belive i have a sub standard inverter.

Any help would greatly appreciated.

Can you provide a schematic of the system?

Sorry been sick and the only one i got is in word. Word doesn’t want to ben lines right.

A more detailed one coming

The ground on L1 on the transformer might be an issue

That is s a typo , that ground symbol shouldn’t be there. That is actually the L1 connection only. it is actually attached to the L2 per their wiring schematic. Neutral (white wire from inverter goes to N on the transformer) , L1 on Inverter goes to L2 on the transformer.

Let me step back a moment and give some history:

Currently, i am running my RV off the 4000w / 40 amp inverter. This works for everything, except when i turned on my AC unit the AC unit overloaded my inverter and drained my 12,000 WH batteries in under 30 minutes.

So, after reading many articles i need to boost my amps tp at least 50 amps, the Victron 100amp transformer with my 4000w / 40 amp inverter is supposed to be able to handle it according to all i read. Autotransformer(see comments/ratings) . I wired the transformer up according the manufacture design in the manual for 120->120/240 step up (split phase).

I wired the 4000w / 40 amp inverter to the transformer and all looked good. My electrical meters showed 2 line of 120±. Then i wired the transformer to the electrical panel to a 240 v 50amp fuse. All that was on in the rv was a small fan and the lights were on. (same load from the first paragraph). I turned on the fuse breaker and the 4000w / 40 amp inverter immediately went into overload and took a decent size charge on my batteries). I checked the next day and batteries got recharged just fine.
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Has your panel ever been used with 240V? Have you checked for a bridge between both phases? It was single phase 120V before, so chances are that theres a simple wire bridging them somewhere

Your inverter was not powerful enough before, so adding the autotransformer didnt change that. If its 4kW were not enough to handle your AC at 120V, then they wont be enough at 240V.

Yes the autotransformer can handle up to 100A, but those need to come from somewhere. The inverter can produce 40A at 120V, but going trough the autotransformer, it will be 20A at 240V. The power stays the same.

In reality the 240V side might only be able to produce 19.5A or something, since nothing is perfect, everything has its resistance and efficiency, and you’re going to loose some power in the transformer

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That is where my thing was going. The comment from the person on the amazon link mentioned he had a 12v 5000W that worked to power the transformer. He claims to be able to run everything on it. So i am going to go with a better inverter, most likely Victron inverter / charger because you can run them in parallel and boost amps.

Thanks for being helpful with this. I appreciate the help. I need to get as close to the 50 amps as i can.