Questions on shore power system

[alaskanviking]

Questions on shore power system

Hi, I’m 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, Water 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 around.
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 unit’s 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 won’t 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

Questions;

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 I’m 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 I’m trying to simplify this so it’s 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 don’t 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. I’d like to plan for the worse in this case and size correctly. The Voltage boost and power boost features, of Victron’s 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.

V/R

Robert

[DotDun]

I see lots of issues.

1) a 125/250V 50A shorepower delivers 12.5KW. You are planning to restrict that with only 7.2KW of isolation transformer(s). That doesn't make sense.

2) I'm bothered by the idea of 'paralleling' the output of the (2) 3.6KW isolation transformers. You can only do that if they are the same phase, if the input is 250V 50A or (2) 30A inputs not on the same phase, sparks will fly.

I need to get past these issues before thinking thru the rest.

[smac999]

I was going to say the same things. You just limited yourself to 30a triple pole main breaker before the transformers. Losing 40% of your plug power. And you can't parallel the transformers outputs.

Get a single 240v 50a transformer.
Then you can run a 50a 240 shore cord or dual 30a 120.

That is as far as I read too.

[alaskanviking]

Originally Posted by DotDun

I see lots of issues.

1) a 125/250V 50A shorepower delivers 12.5KW. You are planning to restrict that with only 7.2KW of isolation transformer(s). That doesn't make sense.

2) I'm bothered by the idea of 'paralleling' the output of the (2) 3.6KW isolation transformers. You can only do that if they are the same phase, if the input is 250V 50A or (2) 30A inputs not on the same phase, sparks will fly.

I need to get past these issues before thinking thru the rest.

Your correct. I'm thinking of 2 30amp 120v recepticals on the pier for 7.6 KW, and forgetting if I plug into a 50 amp 120/240 it would be 12.5kw.

I don't need 12.5 into the boat, 7.2 would be good. I can limit the power by using breakers on the boat side, but it's a little concerning that the system wouldn't be able handle max power if the boat circuit breakers or shore power breakers failed.

I think I am also miscalculating how to wire two together. Thinking more on it, they should have the output set at 120, connect the nuetral, and use the hots from each which would be 240v.

However a little more confusion. If if this is using 2 30amp or 240 split phase from the pier into the primary, the output will be opposite phase. But if I connected 120v or 230v single phase 3 wire, wouldnt that mean both legs are the same phase? Would I get 240v out of the secondaries then? Or would I then have to change the secondaries to 240 and parralel them (which would be the same in that configuration. Switching from split phase to 240 is messing me up a bit.

In the case of the split phase into the two primary, and 240v out of both the secondarys I would not be able to parralel, as they would be different phases

The 240v 5kw inverter charger isn't a split phase, there isn't a neutral connection.

If there is no split phase nuetral is there Phases? Or do the phases come from use of the nuetral?

Or am I just twisting myself up right now lol

Thanks

V/R

Robert

[alaskanviking]

Originally Posted by smac999

I was going to say the same things. You just limited yourself to 30a triple pole main breaker before the transformers. Losing 40% of your plug power. And you can't parallel the transformers outputs.

Get a single 240v 50a transformer.
Then you can run a 50a 240 shore cord or dual 30a 120.

That is as far as I read too.

I have been looking, but there doesn't seem to be a 50a 240v transformer that would work well. The Victron and mastervolt don't use coils so they're lighter. Victron 3.6 was 50lbs. I did find transformers that would work, but they're 160lbs and excessively large. You would also have to open it up and rewire it to change, looked more like an industrial unit.

I don't actually need 50amps 12.5kw coming in to the boat. Two 30 amp would be good. IF I connected to a 120/240 50 amp plug I wanted the system to be able to handle that if the breakers failed.

At this point I'm thinking that may not be possible and I will have to limit using circuit breakers and set the inverter charger to limit shore power inlet to 25 or 30 amps. In which case I only need one isolation transformer.

[DotDun]

You need to establish if having 240V appliances is a requirement. If you can live with 120V appliances, things get a lot easier.

[john61ct]

This may be crazy for this use case but putting it out there.

Nice big bank of quality batteries.

High-amp charger(s) that accept whatever shore power is available anywhere in the world, various plugs and adapters as needed.

Inverter(s) chosen for the specific loads required, 240 or 120 as needed. Yes at good quality like Nagnum these are expensive, but less so, and simpler than transformers,

and many load devices are fine on inexpensive low-amp MSW rather than running everything off one huge PSW.

Obviously ordinary consumers should be DC native wherever possible for efficiency, minimum genny runtimes when away from mains.

[Colin A]

Originally Posted by alaskanviking

I have been looking, but there doesn't seem to be a 50a 240v transformer that would work well. The Victron and mastervolt don't use coils so they're lighter. Victron 3.6 was 50lbs. I did find transformers that would work, but they're 160lbs and excessively large. You would also have to open it up and rewire it to change, looked more like an industrial unit.

I don't actually need 50amps 12.5kw coming in to the boat. Two 30 amp would be good. IF I connected to a 120/240 50 amp plug I wanted the system to be able to handle that if the breakers failed.

At this point I'm thinking that may not be possible and I will have to limit using circuit breakers and set the inverter charger to limit shore power inlet to 25 or 30 amps. In which case I only need one isolation transformer.

If you don't need 240VAC or the higher power of the 120/240 50A connection you can run an adapter to run 2 30A inlets
Y Adapter, 50A 125/250V Male To (2) 30A 125V Females | Marinco



You can look at these transfomers not a huge weight savings but a bit more compact. (note these do not meet current ABYC specs)

Marine-Puck Boat Isolation Transformers | Toroidal Isolation Transformers

[DotDun]

Originally Posted by Colin A

If you don't need 240VAC or the higher power of the 120/240 50A connection you can run an adapter to run 2 30A inlets
Y Adapter, 50A 125/250V Male To (2) 30A 125V Females | Marinco



You can look at these transfomers not a huge weight savings but a bit more compact. (note these do not meet current ABYC specs)

Marine-Puck Boat Isolation Transformers | Toroidal Isolation Transformers

What specs don't they meet?

[Colin A]

Just for Kicks if you really need 240VAC (here in NA 120/240 talking about here) For shore power your stuck with 120/240 50A cord or finding 2 x 30 amp on different legs and a Y adapter with some intelligence inside to make sure you have it right, Like this one.
https://www.hubbell.com/wiringdevice...Q230/p/1631060
You can connect to a single 30A but only your 120 devices on one leg will work. I have used contractors before to allow both legs to have 120 while locking out 240 loads (separate busses) but that gets complicated quick.

[Colin A]

Originally Posted by DotDun

What specs don't they meet?

11.7.1.1


Calls for a metallic grounded enclosure and the one that's a bigger deal also calls for a grounded shield between primary and secondary.

These torrodial transformers don't have the grounded shield. They have become common in the UK and parts of Europe thou, ABYC may look into in the future as I gather it may be outdated.

[DotDun]

Originally Posted by Colin A

11.7.1.1


Calls for a metallic grounded enclosure and the one that's a bigger deal also calls for a grounded shield between primary and secondary.

These torrodial transformers don't have the grounded shield. They have become common in the UK and parts of Europe thou, ABYC may look into in the future as I gather it may be outdated.

Ah, OK. I had a Toroid.com custom build mine, ordered it with the shield between the cores. Shield is connected to shore ground.

[ArmyDaveNY]

While you're installing an upgraded system, you may wish to consider upgrading your cables to a smart plug. They come in 30 and 50 amp versions and the 50 amp plug can handle 250 V.


I read a report, possibly from Boat US, that examined boat fires and of the ones that they could determine the cause for, something like 55% were from electrical issues, and over half of those were from shore power issues.


The issue with the traditional cord such as the Marinco three prong plug is that there are only some 6 square mm of surface area. Add a little corrosion and the heat builds up very quickly. The smart plug has some 190 square mm of surface are for contact. It also has a much improved locking mechanism.


Here's a great link on why the Smart Plug is a much safer and better plug:
https://marinehowto.com/shore-power-...tplug-vs-1938/


Good luck with your project.

[alaskanviking]

Originally Posted by You can look at these transfomers not a huge weight savings but a bit more compact. (note these do not meet current ABYC specs)

[url=http://www.bridgeportmagnetics.com/contents/en-us/d56_Marine_Isolation_Transformers.html

Marine-Puck Boat Isolation Transformers | Toroidal Isolation Transformers[/url]

I haven't seen this brand before, but it looks like it hits the requirements for 12kw shore power. 75lbs isn't much larger than the 50lb Victron. The wiring diagram using two of thier 6kw "marine pucks" is what I had in mind to wire the two 3.6kw Victron isolation transformers.

The wiring for two units appears to be set at 240v incoming, although it appears you can change the wiring. Maybe wire a switch to change. They are also not using the neutral from shore. Where it gets complicated what happens when I wire in 120v or 230v single phase? If L2 comes from neutral and L1 is the 120v or 230v hot line, does the transformer output still come out as 240v? Or since it's the same phase nothing comes out? It almost looks like I wouldn't need an autotransformer to balance the two sides using thier wiring diagram.

Some times cruising your only going to get 120v 30amps, some times 120v/240v split phase, and heading outside of the US 230v 16amps. Im hoping I can work out a flexible wiring on the primary did that accounts for the different voltages.

On the plus side a single 6kw puck would replace two Victron for close to the same power, which would

I do need 240v. My dive compressor needs a 5 HP 230 or 240v motor. Run times are ~30-45 min. Bauer Oceanus. The motor I looked at (needs a replacement) runs on 22amps 240, but even with a easy start/capacitors wired in, the startup load will be around 40 amps or so

240 will be more efficient and the wires carry less amperage. The larger AC motors are a bit more cost effective also. The only thing the isolation transformer is used for is shore power. If I used the 3.6v Victron isolation transformer it would auto switch from 120v/240v simplifying some aspects. But using only 1 would output 240v 16amps, shy of what I need to run the compressor. The inverter charger could pick up the excess load, but we're talking about pulling full power from one 120v 30amp shore power recepticals and that's asking for trouble at a lot of marinas with poor wiring. Why my preference will be to use 2 30 amp recepticals, or 120/240 50 amp if available. 120v 50 amp is rare but also possible.

At my current marina I have 1 120v 30amp and 1 120/240 receptical with only one hot line connected (supposedly 50 amps). I tested these recepticals they are on different phases and I get 240v between the hot lines of both recepticals. They won't rewire So I would have to make my own y adapter to make a single 120/240 receptical from the two. Because the one receptical is breakered with a single 30 amp, does that not limit the other line to 30 amps when wired for 240? Or because it's different breakers one is 30 amps and one is 50? I have been trying to size for 50amps on both lines in case there is a breaker or other malfunction, but I don't need that much power. 25-30 amps at 240. So could I size down slightly to 6-7.5 kw components and not have to worry about overload from a 120/240 50 amp receptical?

Generator would be wired direct to the second input of the inverter charger. And is far simpler and less confusing to wire.

[DotDun]

Originally Posted by alaskanviking

I haven't seen this brand before, but it looks like it hits the requirements for 12kw shore power. 75lbs isn't much larger than the 50lb Victron. The wiring diagram using two of thier 6kw "marine pucks" is what I had in mind to wire the two 3.6kw Victron isolation transformers.

The wiring for two units appears to be set at 240v incoming, although it appears you can change the wiring. Maybe wire a switch to change. They are also not using the neutral from shore. Where it gets complicated what happens when I wire in 120v or 230v single phase? If L2 comes from neutral and L1 is the 120v or 230v hot line, does the transformer output still come out as 240v? Or since it's the same phase nothing comes out? It almost looks like I wouldn't need an autotransformer to balance the two sides using thier wiring diagram.

(1) Changing the primary from 240V to 120V can be done with external 4P transfer switch(es)

(2) The diagram referenced for the dual MP6 is fed with 240V single phase, not sure where you see the complication.

(3) The secondary side of the transformer is a brand new power source, you can create 240V/120V split phase with a single transformer if you want

Originally Posted by alaskanviking

Some times cruising your only going to get 120v 30amps, some times 120v/240v split phase, and heading outside of the US 230v 16amps. Im hoping I can work out a flexible wiring on the primary did that accounts for the different voltages.

I have yet to find a marina with only 120V 30A service, but I don't visit very many marinas, so YMMV.

Originally Posted by alaskanviking

On the plus side a single 6kw puck would replace two Victron for close to the same power, which would

I do need 240v. My dive compressor needs a 5 HP 230 or 240v motor. Run times are ~30-45 min. Bauer Oceanus. The motor I looked at (needs a replacement) runs on 22amps 240, but even with a easy start/capacitors wired in, the startup load will be around 40 amps or so

Generators and inverters care about in-rush current, transformers not so much (although I've heard of problems with Victron transformers).

Originally Posted by alaskanviking

240 will be more efficient and the wires carry less amperage. The larger AC motors are a bit more cost effective also. The only thing the isolation transformer is used for is shore power. If I used the 3.6v Victron isolation transformer it would auto switch from 120v/240v simplifying some aspects. But using only 1 would output 240v 16amps, shy of what I need to run the compressor. The inverter charger could pick up the excess load, but we're talking about pulling full power from one 120v 30amp shore power recepticals and that's asking for trouble at a lot of marinas with poor wiring. Why my preference will be to use 2 30 amp recepticals, or 120/240 50 amp if available. 120v 50 amp is rare but also possible.

At my current marina I have 1 120v 30amp and 1 120/240 receptical with only one hot line connected (supposedly 50 amps). I tested these recepticals they are on different phases and I get 240v between the hot lines of both recepticals. They won't rewire So I would have to make my own y adapter to make a single 120/240 receptical from the two. Because the one receptical is breakered with a single 30 amp, does that not limit the other line to 30 amps when wired for 240? Or because it's different breakers one is 30 amps and one is 50? I have been trying to size for 50amps on both lines in case there is a breaker or other malfunction, but I don't need that much power. 25-30 amps at 240. So could I size down slightly to 6-7.5 kw components and not have to worry about overload from a 120/240 50 amp receptical?

Generator would be wired direct to the second input of the inverter charger. And is far simpler and less confusing to wire.