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Old 21-11-2020, 17:34   #1
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ELCI / Isolation Transformer.

can you use an ELCI breaker and an isolation transformer together in the same AC main line? Do they interfere with each other? from my current level of ignorance i will assume you cant and its one or the other.

does an isolation transformer protect people on board from electric shock in the case of a ground fault or just people in the water?

i really like the idea of using both. if my understanding of ELCI is accurate it would essentially tell you if you have a ground fault as it measures a difference in return AC...the isolation transformer im not clear on wether it does or not but still trying to figure out the AC side.
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Old 21-11-2020, 22:35   #2
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ELCI / Isolation Transformer.

An isolation transformer will remove earth returns as a source of shock currents. Hence you can touch the live wire output from the transformer but not get a shock. To get a shock you have to insert yourself into the circuit , which an RCD ( residual current detector ) will not trigger in this case

Where you don’t have a transformer , an RCD protects against inadvertent return paths including earth

If you have an isolation transformer and you retain the earth wiring , then equally adding an RCD on the output of the transformer after the common neutral earth interconnection is useful as it will trip the output , if the live of the isolation transformer touch’s anything connected to the earth wire ( even though you can’t actually get a shock from it. )

One of the issues with isolation transformers is you an have an undetected live fault , the above scenario helps mitigate that
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Old 22-11-2020, 07:54   #3
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Re: ELCI / Isolation Transformer.

Quote:
Originally Posted by goboatingnow View Post
An isolation transformer will remove earth returns as a source of shock currents. Hence you can touch the live wire output from the transformer but not get a shock. To get a shock you have to insert yourself into the circuit [1], which an RCD ( residual current detector ) will not trigger in this case

Where you don’t have a transformer , an RCD protects against inadvertent return paths including earth

If you have an isolation transformer and you retain the earth wiring , then equally adding an RCD on the output of the transformer after the common neutral earth interconnection is useful as it will trip the output , if the live of the isolation transformer touch’s anything connected to the earth wire ( even though you can’t actually get a shock from it. )

One of the issues with isolation transformers is you an have an undetected live fault , the above scenario helps mitigate that
Indeed.

If an isolation transformer is installed, within 10 feet of the boat’s shore power inlet, an onboard ELCI/RFD breaker is not required, in order to be ABYC compliant.

Some clarification (obscurification?):

[1] Indeed, but only until the first ground-fault occurs. Until that happens, the circuit is isolated, and theoretically touching either wire will not result in electric shock. In practice, capacitive coupling between the primary and secondary, may cause a small current to flow.

RCDs work by monitoring the live and neutral wires by passing them both through what is a small current transformer. If everything is OK the current in on the live wire returns on the neutral, and cancels out, exactly, resulting in a sum of zero. If there is an ground-fault some of the current returns to the supply, via the ground path, the neutral current is reduced, and now the sum of live and neutral currents is non-zero, the RCD detects this, and trips within 100 milliseconds.

ELCI, RCD, GFCI, GFI, & RCBO* devices perform the same function of detecting an amperage imbalance. The difference is in the level of imbalance, or leaking amperage, that trips the breaker. In-home GFI and GFCI breakers trip at very low imbalance levels (5mA), while RCD, ELCI & RCBO* breakers trip at much higher imbalance levels (30mA). Most 30 mA RCDs usually operate at levels between 18 mA and 23 mA, and must trip at 30 mA.

RCD specifications are more complicated in Europe, where they have different Types, AC, A, B, & F (more?), that respond to varying types of earth fault current.

* Residual Current Circuit Breaker with Overcurrent Protection (RCBO) Circuit Breakers also provide overload and short circuit protection, in addition to ground-fault protection.

Peter Kennedy offers some good explanation(s), as do Blue Sea Systems:

ABYC standard for ELCI's explained ~ by Peter Kennedy (PKYS)
https://shop.pkys.com/ABYC-standard-...ined_b_50.html

See also ➥http://assets.bluesea.com/files/reso...50_002-web.pdf
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Old 23-11-2020, 14:09   #4
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Re: ELCI / Isolation Transformer.

Thank you for the clear explanation and link to PKYS

Some time ago, I was looking at ELCI breakers because we have no AC panel and only two GFI receptacles and 30 amp shore connection and I wanted to bring the service up to current code.

I also while doing this wanted to make the shore connect compatible with European standards, then there were heavy discussions about isolation transformers for in water safety (apparently the best/only way to be adequately safe), and it all got too complicated and expensive (ELCI, Isolation Transformer and configuring for 30a 120vac 60hz and European 50hz shore power connections. So I dropped it all. Is the isolation transformer essential for safety, required by ABYC? Will the ELCI take the place of the isolation transformer? Will the isolation transformer help with 60hz vs 50hz? How to deal with the different shore connection plugs and wiring?

Sorry for bringing this complicated question up, but it has been a serious question for me for awhile.

I would be very nice if there were a simple, practical way to address these issues cost effectively, and safely, perhaps resulting in a good diagram?
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Old 23-11-2020, 16:14   #5
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Re: ELCI / Isolation Transformer.

Quote:
Originally Posted by rgleason View Post
Thank you for the clear explanation and link to PKYS

Some time ago, I was looking at ELCI breakers because we have no AC panel and only two GFI receptacles and 30 amp shore connection and I wanted to bring the service up to current code.

I also while doing this wanted to make the shore connect compatible with European standards, then there were heavy discussions about isolation transformers for in water safety (apparently the best/only way to be adequately safe), and it all got too complicated and expensive (ELCI, Isolation Transformer and configuring for 30a 120vac 60hz and European 50hz shore power connections. So I dropped it all. Is the isolation transformer essential for safety, required by ABYC? Will the ELCI take the place of the isolation transformer? Will the isolation transformer help with 60hz vs 50hz? How to deal with the different shore connection plugs and wiring?

Sorry for bringing this complicated question up, but it has been a serious question for me for awhile.

I would be very nice if there were a simple, practical way to address these issues cost effectively, and safely, perhaps resulting in a good diagram?
Yeah i agree. I think im going to skip the transformer for now but i definately am going with an ELCI main breaker before my panel. Still pricey but easy to install and i need a new breaker anyways.
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Old 23-11-2020, 16:33   #6
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Re: ELCI / Isolation Transformer.

I use commonly available 230vac encapsulated isolation transformers available for around €120 https://www.screwfix.ie/p/carroll-me...30v-230v/320hv, these are 1k5 continuous 3kva peak , and represent good value if somewhat peak AC limited ( that’s suits me )

Isolation traffos are really the best solution , I connect the existing boat side protective “ Earth “ wire to the neutral atvthe output of the transformer and fit a standard type AC ( speed S) rated RCBO into that circuit. This provides the hot fault disconnect feature I mentioned . I Typically fit the isolation transformer strapped down in the lazzarette close to the shore power inlet , no further protection is provided

In order to prevent any stray currents flowing I break the input earth to output earth pin links these site transformers typically have . The transformer casing is plastic so this represents zero risk.
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Old 23-11-2020, 16:38   #7
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Re: ELCI / Isolation Transformer.

Quote:
Originally Posted by rgleason View Post
Thank you for the clear explanation and link to PKYS

Some time ago, I was looking at ELCI breakers because we have no AC panel and only two GFI receptacles and 30 amp shore connection and I wanted to bring the service up to current code.

I also while doing this wanted to make the shore connect compatible with European standards, then there were heavy discussions about isolation transformers for in water safety (apparently the best/only way to be adequately safe), and it all got too complicated and expensive (ELCI, Isolation Transformer and configuring for 30a 120vac 60hz and European 50hz shore power connections. So I dropped it all. Is the isolation transformer essential for safety, required by ABYC? Will the ELCI take the place of the isolation transformer? Will the isolation transformer help with 60hz vs 50hz? How to deal with the different shore connection plugs and wiring?

Sorry for bringing this complicated question up, but it has been a serious question for me for awhile.

I would be very nice if there were a simple, practical way to address these issues cost effectively, and safely, perhaps resulting in a good diagram?
One of most cost effective ways to make the boat dual standard is to use a smart battery charger , capable of dual voltages and use an onboard inverter to generate AC.
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Old 23-11-2020, 18:11   #8
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Re: ELCI / Isolation Transformer.

It does not look like Victron has those, but Stirling Procharge Ultra.
  • Input voltage range 90-270 v 40-70 hz
  • Power Factor at 230 v 0.976
  • Efficiency 89.4%
  • Full load current (110/230v) 9.8/4.6
  • Ripple noise (R.M.S.) 14mv
  • Ground leakage 0.5 ma
These are available from 10a to 60a and charge all kinds of batteries.
I know how the DC side would be wired, but how would the AC side work?
They don't have bluetooth interfaces like the Victron equipment.

Would we have to have two different types of connectors for European and US with some kind of a matrix switch arrangement?
Also how and where would the isoloation transformer go, particularly with the dual input (European and US)?
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Old 23-11-2020, 20:06   #9
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Re: ELCI / Isolation Transformer.

FWIW, IN the USA, the xfmr recommended by goboatingnow #6 is not compliant with ABYC Standards.
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Old 23-11-2020, 20:10   #10
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Re: ELCI / Isolation Transformer.

OK, CharlieJ what would you suggest?
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Old 23-11-2020, 20:21   #11
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Re: ELCI / Isolation Transformer.

@rgleason
The ABYC Standard requires that the xfmr is encapsulated and has an electrostatic shield between the primary and secondary windings and this shield is connected to shore safety ground. Further, the case must be metallic, grounded aboard and meet the requirements of UL 1561.
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Old 23-11-2020, 20:35   #12
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Re: ELCI / Isolation Transformer.

The Victron isolation transformers are great and a common choice in the US as well, but there are others being sold by the usual suspects. A 3.6kW model is suitable for a US 30A shore power connection and a 12kW for the 50A connection.

For safety against electrocution and galvanic issues there is nothing that will come near: the transformer is the gold standard.

Also, all residual current devices are fully functional with an isolation transformer. They may never trip but that is because they don’t need to. If something would somehow be wrong, they will trip (but the test button will only work when you ground the ships “neutral”. I guess the test button is important to verify the device and wiring ground is just okay as long as it doesn’t connect to shore ground.
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Old 23-11-2020, 20:41   #13
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Re: ELCI / Isolation Transformer.

Full disclosure: I am a Victron Ambassador. I am also a huge fan of isolation transformers. Unfortunately, Victron isolation xfmr are toroidal and do not have the electrostatic shield required by the ABYC so they are non-compliant.
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Old 23-11-2020, 21:36   #14
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Re: ELCI / Isolation Transformer.

Quote:
Originally Posted by CharlieJ View Post
Full disclosure: I am a Victron Ambassador. I am also a huge fan of isolation transformers. Unfortunately, Victron isolation xfmr are toroidal and do not have the electrostatic shield required by the ABYC so they are non-compliant.
They are toroidal because toroidal transformers are far better. I can see how ABYC likes to see that shield for old style transformers but isolation transformers are not mandatory at all so all it tells me is that they should get on with the times and understand “new” transformer technology.

They conform to IEC standards, which is more European oriented.
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Old 23-11-2020, 21:41   #15
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Re: ELCI / Isolation Transformer.

#14
True that.

BTW, A.N.G. does make toroidal isolation xfmrs that have a shiel and comply with the ABYC Standard.
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