Recommended advanced AC power for EU boats

[Thumbs Up]

Originally Posted by s/v Jedi

Show me the requirement for insulation monitoring for mobile installations.

Lacking subscriptions to current standards I was able to dig up these references which I believe are applicable:
IEEE:

12.7.2 IEEE Std 45-2002, 5.9.6.1, System grounding—general
(changed from IEEE Std 45-1998,11.39.1)
Methods of grounding low-voltage (600 V or less) power distribution system should be determined considering the following:
a) Grounded systems reduce the potential for transient over voltage.
b) To the maximum extent possible, system deign should allow for continuity of service under single-line-to-ground fault
conditions, particularly in distribution systems supplying critical ship's service loads.
c) Systems should be designed to minimize the magnitude of ground fault currents flowing in the hull structure.
To satisfy these criteria, it is recommended that systems be designed per one of the following grounding philosophies:
— Ungrounded, with all current-carrying conductors completely insulated from ground throughout the system. Ungrounded systems
should have provisions for continuous ground fault monitoringhttp://digilib.bppt.go.id/sampul/A_G...tallations.pdf

IEC-60092-507 7.2.1

7.2.1 When a distribution system, whether primary or secondary, for power , lighting or heating, with no connection to earth is used, a device capable of continuously monitoring the insulation level to earth and of giving acoustical or optical indication of low insulation values should be providedhttps://documents.pub/document/iec-6...n-general.html

[s/v Jedi]

Originally Posted by Thumbs Up

Lacking subscriptions to current standards I was able to dig up these references which I believe are applicable:
IEEE:

IEC-60092-507 7.2.1

Well, this is great! Thank you for digging up the documents. I see that I set you off to a substantial knowledge gathering spree

So from these documents it is clear that the isolated (I call it floating) system is superior to the grounded system for reasons that I did list before but not as nice as these documents. I used to have a Victron document that I used to quote from but I have trouble locating it.

The ground insulation fault monitoring is described and recommended (they say “should”, not “must”) for both grounded and insulated power, not just for insulated power. This is because these documents are for IMO registered vessels... private yachts are exempt. That doesn’t mean it’s not wise to do, but I would recommend a periodical check instead of continuous.

Here’s the reasoning: you have improved availability because everything keeps working even during the first fault. From there on, it’s exactly like a grounded system (you have that fault acting like the neutral to ground jumper in a grounded system) so you also lost that advantage of improved availability. Now, the AC power on our yachts is not as critical as on a cruise liner, operating room etc. so if the second failure happens and the breaker trips, we’re not in a big bunch of trouble. But it’s better to detect the first fault and fix it.

On another note, these documents describe everything.. also why the hull should not be a return path. This is why I recommend a separate AC ground. The more you isolate, the better it gets. Someone described it as an extension cord from shore into the boat to power an appliance.

I am changing some details in my diagrams as the result of these discussions... this is why I like to do these. I’m also finding normal priced UL listed ELCI breakers in the US. These are not required when the isolation transformer is close enough to the power inlet, but at only a couple bucks extra, why not. I’m also changing the surge protection.

Last but not least I have been trying to find reasons why a 7kW shore power (EU standard) isn’t enough and we need a 12kW (US standard) instead. I can’t so I’ll probably put a 7kW transformer in my “ultimate diagram as well. I found that Hubbell makes a decent 15kW transformer in stainless steel... it’s big, heavy and $1,800 but I can see big boats use that so will make it an option.

[Thumbs Up]

Researching all of this sent me off on some tangents for sure. I discovered the stray current problem of multi grounded utility neutral distribution systems. Did you guys know that the grounding rods and water pipe connections at service entrances are part of a high voltage return path? That the neutral connection in buildings is shared with the 7000 volt utility line neutral? This is a problem studied by the dairy industry. When we connect underwater metals of boats to shore ground, as per ABYC, we become part of a 7000 volt return path for unbalanced high voltage return currents. This is true in North America, Australia, and many other places. My struggle to understand ground loops and grounding impedance has taken a new turn. The requirement to only use one grounding rod near a service entrance only is now clear. There are high voltage utility return currents travelling through and over the earth! We are electrified!
file:///C:/Users/Guest/Downloads/EQU...IAL_PLANES.pdf
https://www.ecs.csun.edu/~bruno/Mult...nal_4-17-7.pdf

[poiu]

Jedi. I’ve ditched my isolation transformer. I rely on a RCD for safety and I think stray earth current problems are really rare and if you detect one you could just unplug. If you must have one, consider Maxpower as they do a switch mode device I think. It is much lighter.

I like the MultiPlus units and the way they invert and charge. You have redundancy and simplification. I don’t have them, but I will get them next time. I think Mastervolt do linking units too now. They didn’t do so previously.

[David B]

Originally Posted by s/v Jedi

Can you post some links to the 32A inlet and shore power plugs/cables? I’m having trouble finding these here in the Americas, even though 16A isn’t too hard to find.

I’ll probably adapt to your setup with the 32A inlet for EU boats even when only using a 3.6kW transformer... which allows them to use 120V 30A shore power.

For protection I think a 32A ELCI works. If only a 3.6kW transformer is used, you simply put a 16A breaker behind that to limit it’s output current. The whole path from shore outlet, cable, boat inlet, ELCI to transformer is 32A rated. Many EU boats find themselves with a 16A ELCI which is costly to upgrade to 32A.

If you have a link to a DIN rail style 32A ELCI breaker that would be great as well.

You mean these?

https://www.ebay.com.au/itm/18473172...4AAOSwEP5gnwzt

https://www.ebay.com.au/itm/17442389...QAAOSwKgdac3WR

https://www.ebay.com.au/itm/15371170...cAAOSwFZddwWKx

https://www.ebay.com.au/itm/18343800...AAAOSwZRlbntZp

The line plugs I usually get from our local electrical trade outlet, as with the line sockets. Especially with the sockets, I keep a few onboard, and when confronted with yet another pedestal connector, source one at the local chandlery and make up yet another 'something' to 32A line socket adaptor lead.
So far we have:
3-P 16A & 32A to Marinco (our main shore leads)
5-p 16A & 32A to 3-p 16A & 32A line sockets
5-p 125A to 32A line socket
3-p 300A (from memory) to 32A line socket
3-p Schuko to 16A line socket
3-P 32A to 3-P 16A line socket
3-p 32A to 3-p 16A & 32A line sockets ('Y' adaptor)
Plus a couple of others I cannot remember at the moment

The breakers would come from the trade outlet too (but the boat is factory wired with 16A and 32A circuits, so that's taken care of).

The Marinco inlets are another thing, and the price varies wildly .....

[Baronkrak]

Originally Posted by Thumbs Up

….. The diagram is showing a fully floating A/C distribution system ….

Not at all. A fully floating A/C system would not have:
A Ships Ground
Interconnecting Green wiring.

A fully floating A/C system would have per circuit:
Only one appliance that require to be earthed.

Note: circuit breakers prevent overload, do not prevent electrocution.

[WHEELEYBIN]

Originally Posted by Baronkrak

Not at all. A fully floating A/C system would not have:
A Ships Ground
Interconnecting Green wiring.

A fully floating A/C system would have per circuit:
Only one appliance that require to be earthed.

Note: circuit breakers prevent overload, do not prevent electrocution.

Correct about circuit breakers but if you use an RCBO coupled with an RVD(Residual Voltage Device) on the outlet of a Victron Combi and turn off the earth link you have human safety this is proven to work and Australia exceeds the standards and is gaining popularity.
Please research RVD-SAFE .

[s/v Jedi]

Originally Posted by WHEELEYBIN

Correct about circuit breakers but if you use an RCBO coupled with an RVD(Residual Voltage Device) on the outlet of a Victron Combi and turn off the earth link you have human safety this is proven to work and Australia exceeds the standards and is gaining popularity.
Please research RVD-SAFE .

You don’t need it behind an isolation transformer, but it’s protection comes pretty close. The thing is that by definition the isolation transformer is always the best option because it is 100% galvanically isolated

[Baronkrak]

Originally Posted by Baronkrak

…..1…1. Fully floating is safer,….

Originally Posted by WHEELEYBIN

….Please research RVD-SAFE .

« We are Australian Owned, Australian Designed, Australian Made and Supported with genuine Australian Warranty?.

You are joking ?

[Lyric]

Originally Posted by s/v Jedi

This post requires some clarification:

It is valid for all power systems that have one phase and a neutral. It is not valid for US split phase, for which I will post a separate diagram later.

The shore power norm in the EU is 230V at either 16A or 32A. Victron has an isolation transformer for either option, but there are consequences to the choice:

- I never saw a 32A outlet anywhere. Of course they will exist somewhere, but they are very rare.

- The Victron 7kW isolation transformer is 230V in/out only. It does not allow you to change a jumper and connect to a US 120V outlet like the 3.6kW transformer does.

For above reasons I recommend to use a 3.6kW transformer with 16A inlet. But I also recommend to upgrade all inlet wiring incl. shore power cord to 6mm2 (10AWG) so that it can be adapted for use with a US 120V shore power outlet. This is why the input breaker is 32A even for a 16A inlet.

Do not worry about 3.6kW not being enough to run everything aboard: the inverter/chargers have Power Assist which can add 6kW for a total of more than 9kW of available power. The 3.6kW, added to solar power generated, must be enough for the average consumption so that the batteries get charged when power demand is lower.

An advanced AC power system like this used to be for the big boats. Today, with solar power, lithium batteries and electric galleys on the rise, it has become normal for boats from 12 meter (40') and up.

This diagram is not all that is needed. It assumes you have lots of power generation systems, mainly solar (recommend 1500W minimum to mostly eliminate genset use), aboard as well as at least a 10kWh 24V lithium battery. These numbers are based on my direct experience... which may change in the future as we only have such a system for 6 months.

The diagram has two 3kW inverters instead of smaller ones or one larger model. The total 6kW is required for the all-electric option and multiple units provide redundancy and price effectiveness.

There is an old fashioned manual transfer switch to change between shore power and generator. This switching is typically not done often, with the manual switch being much more reliable than an automatic transfer switch or a Quattro inverter/charger setup which have two inputs... at much higher price. The only reason to select a Quattro would be higher capacity.

There are three output busses. Two are familiar as they connect to OUT1 and OUT2 of the Multiplus units, where OUT2 only gets power when shore power or genset power is available.

This can be changed in case you want to operate the inverter/chargers independently instead of in parallel. in that case bus 1 becomes the output of the first unit and bus 2 the second unit. This setup has a powerful benefit: using the breakers around the inverter/chargers, one can be forced to only charge the battery while the other can be forced to inverter mode. This allows the use of 50Hz power aboard while connected to 60Hz shore power. If this is used often and/or full inverter power is needed, a third unit or just a battery charger can be added to the diagram.

Bus 3 is a bypass bus. This can be used like the OUT2 for power only from shore or genset but it's also useful in case of equipment problems.

The distribution breakers are double pole for additional safety as well as flexibility and future modifications.

I have examples of panels included. Note that single pole breaker panels can be modified to double pole and that panels with rotary switches are available as well. I don't have these panels yet but plan to have them custom fabricated by online services that do just that.

Hi S/V Jedi. I have been reading this discussion thread as well as others you've been a part of about IT Network wiring with much interest and I very much appreciate your contributions. The Victron literature isn't always clear to me especially since I don't have their hardware in front of me yet to test. My question to you is with the green wire in your EU diagram. Is it necessary? Maybe I am not understanding what you are showing or otherwise it is Victron I am misinterpreting but if you look at their .PDF "Wiring Unlimited" (english version) page 61 they depict a simple IT Network without the green "ground" wire. Is your green wire there to comply with shore power hookup grounding/earthing while on land or something else?

I would have thought that if there was an isolation transformer without the ground/earth connected to the output that the system after the isolation transformer would be just an IT Network. To further confuse what is probably simple is the manual for the isolation transformer on page 9 says that a jumper is needed between J21 and J23 to allow a necessary RCD to function at the output side of the isolation transformer but I feel that is in contradiction to their "Wiring Unlimited" page 61 IT Network diagram.

I want a safe IT Network AC at the dock and while at sea to play nice with my fully isolated DC setup. I was planning on using the 2000 watt isolation transformer together with the compact Multiplus 12/1600/70 along with other Victron DC hardware components with a REQ BMS.

Thanks in advance for any clarity you can offer.

[s/v Jedi]

Originally Posted by Lyric

Hi S/V Jedi. I have been reading this discussion thread as well as others you've been a part of about IT Network wiring with much interest and I very much appreciate your contributions. The Victron literature isn't always clear to me especially since I don't have their hardware in front of me yet to test. My question to you is with the green wire in your EU diagram. Is it necessary? Maybe I am not understanding what you are showing or otherwise it is Victron I am misinterpreting but if you look at their .PDF "Wiring Unlimited" (english version) page 61 they depict a simple IT Network without the green "ground" wire. Is your green wire there to comply with shore power hookup grounding/earthing while on land or something else?

I would have thought that if there was an isolation transformer without the ground/earth connected to the output that the system after the isolation transformer would be just an IT Network. To further confuse what is probably simple is the manual for the isolation transformer on page 9 says that a jumper is needed between J21 and J23 to allow a necessary RCD to function at the output side of the isolation transformer but I feel that is in contradiction to their "Wiring Unlimited" page 61 IT Network diagram.

I want a safe IT Network AC at the dock and while at sea to play nice with my fully isolated DC setup. I was planning on using the 2000 watt isolation transformer together with the compact Multiplus 12/1600/70 along with other Victron DC hardware components with a REQ BMS.

Thanks in advance for any clarity you can offer.

It’s gonna sound silly but apart for power use while hauled out (which I think requires grounding) the biggest reason for having the ground wire is so that the test button on gfci outlets work. I mean that literally, so the gfci protection will work without the ground wire but the test button doesn’t.

It’s pretty easy to put it in though, as long as it’s made sure that no other wires from DC power or engine blocks or bonding systems connect to it. Just the AC power and of-course not the primary side of the isolation transformer

[manitu]

To clear up some misunderstandings:

Using a isolation transformer makes the ships's AC system ISOLATED.
no ground cable at all makes it UNGROUNDED , and not IT (isolated terra) or TN (terra neutral).
Connecting Ships "ground" wire to the transformers N output JUST BEFORE a GFCI breaker, but NOT to ships submerged metal structure makes it a ISOLATED "TN" system.

To get a IT-system you should connect the ground wire to the center tap of the transformer. This makes the highest live-to-earth voltage onboard about 115v, and much more survivable than 230.

I'm not up to date on connecting "isolated ground" to ships metal ground , according to code.
Both has pro's and con's.

.manitu

[s/v Jedi]

Originally Posted by manitu

To clear up some misunderstandings:

Using a isolation transformer makes the ships's AC system ISOLATED.
no ground cable at all makes it UNGROUNDED , and not IT (isolated terra) or TN (terra neutral).
Connecting Ships "ground" wire to the transformers N output JUST BEFORE a GFCI breaker, but NOT to ships submerged metal structure makes it a ISOLATED "TN" system.

To get a IT-system you should connect the ground wire to the center tap of the transformer. This makes the highest live-to-earth voltage onboard about 115v, and much more survivable than 230.

I'm not up to date on connecting "isolated ground" to ships metal ground , according to code.
Both has pro's and con's.

.manitu

With the ground wire connected as shown in my diagram, the highest live to earth voltage is zero Volt, so better than 115V (but this is an EU 230V schematic so all moot point)

[Lyric]

Here is the Victron literature I mentioned:

[s/v Jedi]

Originally Posted by Lyric

Here is the Victron literature I mentioned:

Yes, and that info is correct. It says that the ground (earthing) conductor is not installed. Even though we install the conductor, it is not connected to any power carrying conductor, just to ground lugs on outlets, inverters etc.

This means that the test buttons on gfci outlets work plus it enables switching to a grounded network while on the hard (Victron isolation transformers come with a jumper for that).