Questions on shore power
Hi, Iím trying to update my shore power
system similar to the one used by SV Jedi. From My Design to My Installation: New AC Power System [Sitemap] - Cruisers & Sailing Forums
and Jedi AC power system (English) - s/v Jedi
I am putting in the more complicated and higher power system to allow power input from any local and to support 240v dive compressor
maker, and possible A/C. My system differs in a few regards but brings up a couple of questions that are difficult to wrap my head
To allow any incoming voltage to 240v, my plan is to replace my shore power inlet with a 50 amp 240v shore power inlet. I know the 240/50 cables
are heavier and way more expensive, but I prefer the flexibility of using any power source. On the dock
side I will use adapters to allow me to take from two 30amp 120v plugs, or one 240v 50amp plug
. Like S/V Jedi the goal is to get 240v to the boat
if possible. It may be possible to use a 50amp single
phase cord as it will be cheaper and lighter, but I really have to look at adapter wiring
On the boat
side Instead of using one isolation transformer I plan to use two of the Victron 3600watt auto isolation transformers. L1 and neutral will go to one, and L2 and neutral will go to the other. These isolation transformers will automatically sense incoming voltage and switch the unitís inputs for 120v or 240v. The output will be set for 240v output regardless and will be paralleled. 230v and 120v single
phase will use an adapter to power to both L1 and L2 allowing both transformers to be used. That is to protect the system from a large AC load pulling more than 30amps from the circuit when plugged into 50 amp shore power. IF I need the power it would be available i.e. A/C.
From the isolation transformers I wonít use the neutral connection and parrelle the 240v outputs for L1 and L2. This makes it a floating 240v. at that point I believe I have two options;
1. same as S/V Jedi. Isolation transformer to a large 230 (euro spec) Victron Quattro inverter charger
. I am looking at the 5kw model due to the large dive compressor
. The output of the inverter charger
goes to a Victron Auto transformer (this is a different thing than an auto isolation transformer) which balances both legs and gives me my neutral line into my circuit breaker panel. If I use a 5kw inverter charger, using the power boost feature I am looking at a potential 8kw or 11kw into the circuit panel.
2. the second option is to connect the isolation transformers to the autotransformer, and then connect the auto transformer to two 120v 3600 watt inverter chargers. One using L1 and the neutral from the auto transformer, and the second using L2 and the neutral from the auto transformer. L1, L2 and neutral would go to the circuit breaker panel. This would let me use a smaller cheaper 3600watt auto transformer instead of the larger heavier 100amp transformer if it was placed before the inverter chargers. In theory I could use the older 120v 3.6kw Victron Multiplus inverter charger I already have and same money
by just purchasing
a second one. The setup is more complicated setting up the two inverter chargers as 240v single phase, making it more difficult for anyone working on the system later. In theory this would boost my power from the inverters to the circuit board to 60 amps, 30amps per side, am I incorrect? That extra boost assists with starting the larger dive compressor
IF I use two shore power sockets from the pier, two 30amp 120v, that use separate un connected circuit breakers and on different phases, does this essentially mean I have available 30amps 120v on L1 and 30 amps 120v on L2 for a total of 30 amps 240v (vice the normal 16 amp x 240v) coming out the output of the isolation transformers?
If it was a 30amp 120 and a 50amp 120 would that mean Iím looking at 240v 41 amps to the isolation transformers? I am assuming in this case that power would be restricted to the size of the isolation transformer, 240v 16 amps output from each transformer, paralleled output would push 240v 32amps into the inverter charger or auto transformer? That sounds suspiciously like I would need to use the larger 100 amp auto transformer regardless.
Am I correct that using two 3600 watt inverter chargers connected will output 240v 30 amps (120v 30 amps on L1 and 120v 30 amps on L2), and does that mean I need to size L1 and L2 to the circuit panel for 30 amps, and the neutral wire for 60 amps? (FYI Iím trying to simplify this so itís easier to understand, I would also have to account for the power boost from a generator
or shore power which could change depending on the other questions and if I am getting 208v or 240v from the pier)
If using two receptacles, I only brought the L1, L2, and neutral lines from the pier i.e. using a smaller 50 or 30amp 120v 3 wire shore power cord, am I correct that I can only get 240v 16amps to the boat regardless if one is from a 50amp receptacle and one is from a 30 amp, as this would balance between the two lines and match the smaller amperage?
If I do get 240v 30 ampts into the inverter charger, if it is a single 240v 5kw inverter charger and using power boost does than mean I would have ~ 12.2kw or 240v 51 amps available?
I am trying to plan things out appropriately and ensure I understand, so that I can use the right size wire and equipment
. I understand that I donít have to use full power from the pier, and that I will only get the power listed on the circuit breakers from the boat and the pier, IF that all works correctly. I have seen some skeptical shore power towers, and heard bad stories. Iíd like to plan for the worse in this case and size correctly. The Voltage boost and power boost features, of Victronís inverter chargers does complicate things a little, but thinking about the diffrent voltages and possible amperages from two separate receptacles compared to a single 240v 50amp kind of threw me a little. I have ~ 15 years of experience working on small boat
diesels and electrical
systems for the Navy
, and will probably get my ABYC electrical certification
next year if I can swing the leave and schedule. I wont be completing this conversion until this winter/spring so i do have a little time to work
this all out.