Galvanic Isolator or Isolation Transformer

[alaskanviking]

The S/V Jedi route is to connect the outlet of the transformer wired for 240v as a floating ground to a Victron inverter, then the outlet of that is wired to a Victron auto transformer also as a floating ground. A floating ground is where you use L1 and L2 but don’t use Neutral/Ground, OR in a 230v system you use the Hot and the neutral but don’t use the ground. The outlet of the autotransformer gives you your ground/neutral wire to wire into your ac panel and will balance both legs of your 240v split phase power. IE it lets you use all of your power instead of overloading one leg. As an example say you have 2 30amp 120v plugs coming in. You roughly have 30 amps available per line. The A/C is on one at 25 amps, leaving you 30 amps for charger, water heater, ac power in the boat. You’re limited for any one consumer by the max amps on a line. If this was a 50amp plug this would pop a breaker. Add starting surge amperage for large motors like a water maker, A/C, large AC Refrigeration, and you will easily max out your shore power, IF you had both lines on separate isolation transformers feeding an auto transformer it would balance across both lines so you can have a max load for both ( 2 30amp , would give you 60amp available). This is good if you already have 240v coming in, or too much regularly used equipment on one line where you have to limit what’s on at the same time, or have big equipment or motors. A good plus with this set up is you can install a larger A/C that has a big starting load over 25 amps with 2 phase setup (120v A/C), or over 30 amps with 2 30amp 120v cables. It also gives you a little redundancy if you’re using shore power and it provides less than standard amperage or voltage. Another place where this would be good is if you use 2 inverter/chargers, 1 per line. You’re limited to the max power of the inverter per line. So in usage say you’re running a bunch of stuff on one line and then the wife uses the hairdryer ect. Safety concern here too if your running close to max amps on one cable for hours like on a hot day with a/c, asking for fire. I may not be explaining this well but the essence is this shares all the loads on the boat equally across both lines so you’re not overloading or overheating one any line or cable.

I am putting together a similar system to allow me to run a 5hp dive compressor on the boat. Considering only running amperage, the motor can be run off of a 30amp cable, or one line from 240v without blowing a breaker. However the starting surge of the motor is somewhere between 35-45 amps which makes that all pretty much impossible without plugging the compressor directly to a 240V shore power cable. This all applies to a generator as well, and I would have to turn everything off and wire the generator for 240v to start the motor using a 3-5k generator. Using a S/V Jedi setup and the Victron inverter chargers and some other tricks like soft starts ect gives me a workable solution.

Robert