I'm in the process of doing something similar. This is based off of work from S/V Jedi, in several other
forums. The switch schematics come from a technician at bridgeport magnetics. You can do this with just one transformer instead of two
I needed to run a 5hp
scuba compressor. This part has changed since 2019, as I'm now using a 5hp 3ph
motor with a VFD for the easy start feature. Reduces the starting amp load considerably. Just tested, so this works. I have to get a clamp ammeter to verify actual power draw, and I'm picking up a different 5hp
motor with higher
RPM to match the stock motor.
So this was put together so the shore power feeds into the isolation transformer using a switch to select voltage. Custom wired transformer from bridgeport magnetics has leads for all the different voltages available in the US and globally in theory. Isolation transformer has set 240v output.
240v from transformer to 240v quattro or multiplus inverter
charger. No neutral just the two hot leads. For generator wire it 240 I to the quattro. A later revision had generator to a switch into a multiplus. I'm using a 5k inverter charger for the
scuba compressor.
Inverter charger 240v is wired to
victron auto transformer, no neutral and only the two floating hot leads. This fully balances both 120v legs so you can use full power across either leg with out popping a breaker. So if I have 2 30amp
cables coming in I can use 60 amps on one leg if I plugged enough stuff in. theorietical and in reality I set things so I can't pull full amps from shore power.
In your setup your limited on each leg to the size of 1 inverter/charger. So you can only have a max combo of ac load of 3000 watts for a 3k inverter charger. So a heat gun, and wife's curling iron could possibly trip the breaker.
The 2 hot leads and neutral come from the output of the auto transformer, which is then wired to the breaker panel with 2 split legs of 120v. The inverter charger will boost voltage slightly and can tap into the batteries if I need a bit more power, say I was starting a 28amp scuba compressor (14amp @ 240v)
I'm using two isolation transformers and the 100amp auto transformer with a 5k inverter charger. This lets me get close to using the full 12000wtts available from a 50amp 240v shore power cable. However the benefit is I can plug in a 1 50a 120v, 1 or 2 30 amp
cables, or 1 or 2 230v euro cables 16amp or 32 amp, depending on what's available and always get my 240 output balanced across the cables. Another added benefit is I can wire adapters so I take a 4 wire 240v 50amp shore power into a 3 wire 50a 120v cable, for a lighter cable setup. This setup is a bit more complicated but makes the system more flexible globally theoretically.
In your setup you could in theory wire the auto transformer before the inverter chargers to balance the shore power or generator load but I don't think you would get the same effect of balancing the loads from your inverter chargers. In theory you could connect the neutrals of the inverter chargers and float the 2 hot wires to an auto transformer but I haven't looking into this
wiring or the
manuals to know if that's a functional option. 2 inverters do add some redundancy, but cost more than a single 240v charger. Keep in mind two 120v inverter chargers set to split phase can fail, or reset, and you must ensure you reprogram correctly before reconnecting to your panel. It's been over a year since I looked into the
manuals and
wiring diagrams figuring this stuff out so I victim would be better help with that setup. I was thinking thay way two before I stumbled into the S/V Jedi way, and talked to bridgeport magnetics.
If you sized things down some say to pull from 2 30amp cables you could switch to 1 isolation charger, the smaller auto transformer, and easier wiring for less cost. Victron has nice isolation transformers including an auto voltage one, but they did not have the capacity. The other brands were too small, too expensive, or too big.
In Test running the VFD i found other advantages with this setup. The vfd can be setup to lower the HZ to drop power or can increase HZ up to 120hz (double) for a power boost. I can wire it up to a speed knob so I can drop to say 80% when at
anchor, and boost to 120% when engine/gen is running. The easy start will let it run off a 30amp shore power connection or batteries with a big enough bank. Very promising, I may go with a 3ph motor for a
water maker or any other large ac motor for the same reasons. A wash down
pump that can be boosted when you need a little extra oomph would be nice.
I haven't refined these files in over a year, there has been changed, and updates I haven't put down on paper fully yet. I put it together after much consultation of the manuals, and conversations with victron and bridgeport magnetics. Use it as a reference if you want, but make sure the wiring will match your system. I'm not responsible for any damages or injury if you do this and don't understand the systems or set something up incorrectly.
Vedrfolnir_Shorepower-AC system wiring-equip detail-Jan2019.pdfVedrfolnir_Shorepower-AC system wiring diagram-switch-27NOV2019.pdf
Maybe if I keep this old watermaker I'll just fork off the generator input line directly, since that's realistically the only way I'd ever run it, and then run the two quattros + an autotransformer in balance mode...
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