ELCI with Isolation Transformer and Inverter/Charger

[goboatingnow]

Originally Posted by CharlieJ

@goboatingnow # 26



For your information, the Electrical Project Technical Committee is the ABYC group of volunteers that create the various electrical standards. It is comprised of 28 formal members from all areas of the marine industry: e.g., Brunswick Corporation, Blue Sea Systems, Underwriter Laboratories, marine surveyors, USCG, service sector, marine technical authors, etc., etc. Collectively there is a vast knowledge base of all things dealing with the marine electrical world.

Clearly that knowledge doesn't extend to ELCIs , isolating transformers or bonding in my view. I'll stick to ISO who have a better understanding

[CharlieJ]

#30
And I will stick to the knowledge base of the industry experts on the PTC over some unknown poster on a forum.

[shimari]

Originally Posted by shimari

Correct you need an isolation transformer to do the voltage conversion - 230/60 in and 230/50 out of the inverter without the power assist.

I'll look into turning the pass thru off. I'm looking into this as it seems the only boats I like set-up for 230/50, and I want to understand the problems if I go that route.

Unfortunately, pass thru can't be turned off (at least on a Mass combi).


That leaves either installing a stand-alone battery charger and running things off of the inverter at 230/50. Or, installing an isolation transformer and running everything at 240/60.

[goboatingnow]

Originally Posted by CharlieJ

#30
And I will stick to the knowledge base of the industry experts on the PTC over some unknown poster on a forum.

hardly unknown here since 2009 and I know my ISO specs. The fact remains ABYC doesn't understand isolation transformers and only " discovered " ELCIs about 10 years ago , when they have been in general use in Europe in houses , on marinas and in boats for 25 years

The bonding recommendations date from wooden boats and make no sense for a modern GRP vessel and contribute to impressed corrosion and all the issues of degrading seacocks, ABYC need to modify their recommendations to be in line with the better thought out ISO electrical specs, which were actually developed by technical experts without any commercial imperative

As S/V jedi and I have maintained there are flaws in the ABYC approach ( The insistence on a electrostatic shield is a classic one as this is NOT a safety device )

[s/v Jedi]

Originally Posted by CharlieJ

#30
And I will stick to the knowledge base of the industry experts on the PTC over some unknown poster on a forum.

Sorry Charlie but the IEC standards are not just a national institution of volunteer experts, it is a worldwide organization, founded in 1906 with 89 countries as member and a 20 million budget. If we compare experts, then this organization comes on top, in close cooperation with ISO and ITU.

On the subject of this thread, they have demonstrated to be decennia ahead of ABYC.

[s/v Jedi]

Originally Posted by shimari

Unfortunately, pass thru can't be turned off (at least on a Mass combi).


That leaves either installing a stand-alone battery charger and running things off of the inverter at 230/50. Or, installing an isolation transformer and running everything at 240/60.

Instead of blocking pass through, you just turn the output breakers off. This will make it a battery charger.

[Texlan]

Originally Posted by CharlieJ

#30
And I will stick to the knowledge base of the industry experts on the PTC over some unknown poster on a forum.

I wasn't trying to convince you, you didn't have to put me down. I was merely offering my interpretation of the situation to the op/others as an american boat owner who is confused by the ABYC standards' lack of clarity on this particular subject (ELCIs around an Iso xfmr + inverter/charger). Some parts are clear (transformer more than 10 feet from inlet, put in ELCI) some are not clear (all diagrams only show branch circuits after iso transformer, do not show how to deal with other independent sources after iso transformer neutral/ground bond that also neutral/ground bond.. .like an inverter charger when it's inverting (or God forbid boosting). or a genset.)


I am an extra class amateur radio operator, I kinda now a thing or two about electricity, so I am inclined to believe that the lack of clarity is real and not a problem in my reading/comprehension skills.

Also goboatingnow's point about abyc requiring a grounded shield between the primary and secondary is also a good point. It's REALLY hard to find any commercially available iso transformers that actually meet this requirement. It's a little confusing why they would do that.


In any case, if my air conditioner pump's green ground wire breaks in 5 years, and my pump shorts its hot to its case in 7 years and leaks current through my wet stringers, to my bilge, to my dc ground via a bilge pump, and back to my iso transformer via the dc negative to ac ground bond, at the point the current reaches 30ma an ELCI on the output of either the iso transformer or the inverter(when it's inverting) would trip.

I'd rather find out a problem existed when my ELCI tripped then find out while grabbing onto the engine with my left hand while I reach down with my right into my bilge to clean the damn bilge pump grate again.

If i'm going to be an "unknown poster on a forum," I want to be a live one. YMMV.

Peace...

Sean
WK7R

[s/v Jedi]

Originally Posted by Texlan

I wasn't trying to convince you, you didn't have to put me down. I was merely offering my interpretation of the situation to the op/others as an american boat owner who is confused by the ABYC standards' lack of clarity on this particular subject (ELCIs around an Iso xfmr + inverter/charger). Some parts are clear (transformer more than 10 feet from inlet, put in ELCI) some are not clear (all diagrams only show branch circuits after iso transformer, do not show how to deal with other independent sources after iso transformer neutral/ground bond that also neutral/ground bond.. .like an inverter charger when it's inverting (or God forbid boosting). or a genset.)


I am an extra class amateur radio operator, I kinda now a thing or two about electricity, so I am inclined to believe that the lack of clarity is real and not a problem in my reading/comprehension skills.

Also goboatingnow's point about abyc requiring a grounded shield between the primary and secondary is also a good point. It's REALLY hard to find any commercially available iso transformers that actually meet this requirement. It's a little confusing why they would do that.


In any case, if my air conditioner pump's green ground wire breaks in 5 years, and my pump shorts its hot to its case in 7 years and leaks current through my wet stringers, to my bilge, to my dc ground via a bilge pump, and back to my iso transformer via the dc negative to ac ground bond, at the point the current reaches 30ma an ELCI on the output of either the iso transformer or the inverter(when it's inverting) would trip.

I'd rather find out a problem existed when my ELCI tripped then find out while grabbing onto the engine with my left hand while I reach down with my right into my bilge to clean the damn bilge pump grate again.

If i'm going to be an "unknown poster on a forum," I want to be a live one. YMMV.

Peace...

Sean
WK7R

Have you considered that the manufacturer of that one transformer that complies with the recommendation may supply one of the “volunteers” to the committee that writes the recommendations?

Also, if behind the isolation transformer, I do not recommend to bond AC ground nor any other AC conductor to anything and that includes other AC conductors. After doing the best job possible by isolating the AC, bonding it to other things can only make it worse.

[goboatingnow]

the secret to isolation sucess

RCBO( ELCI) on the input lead adjacent to the shore power entry point , many European boats already have this as opposed to the one on the panel

Isolating transformer with or without electrostatic shield , optional RCBO on the traffo output, doubles as main output over current breaker

no connection between shore protective earth and boat protective earth or any boat fittings or DC negative

No connection between boat protective earth and any DC connection whatsoever

Dont bond underwater fittings together on a modern GRP boat

Youll be a safe and happy camper

( if it was available and affordable an isolated SMPS convertor would actually be better as you could change input voltage and frequency )

[s/v Jedi]

Some pictures with ideas/hints:

- use crimped ferrules to connect big conductors to shore power inlets (30A and 50A SmartPlugs shown)

- when your isolation transformer allows 1:2 so that you can get 240V from a 30A 120V shore outlet, then you must have breakers on primary side (30A) and secondary side as well (15A)

- don’t forget the breaker for the genset

- also a galvanic isolator and a surge suppressor are in this picture: see our full diagram for setup.

[Statistical]

Originally Posted by s/v Jedi

Some pictures with ideas/hints:

- use crimped ferrules to connect big conductors to shore power inlets (30A and 50A SmartPlugs shown)

- when your isolation transformer allows 1:2 so that you can get 240V from a 30A 120V shore outlet, then you must have breakers on primary side (30A) and secondary side as well (15A)

- don’t forget the breaker for the genset

- also a galvanic isolator and a surge suppressor are in this picture: see our full diagram for setup.

Nice DINrail setup. Curious why you have both 50A and 30A shore inlets. Couldn't you use 50A for everything?

[goboatingnow]

WHy no RCBOs ( ELCOs) though ?

[s/v Jedi]

Originally Posted by Statistical

Nice DINrail setup. Curious why you have both 50A and 30A shore inlets. Couldn't you use 50A for everything?

My 50A inlet does not have a transformer (yet) and there are many places where only 30A/120V is available.

Now that we have plenty solar power we’ve been in marinas using our A/C without even connecting shore power, so I am considering going back to just simply the 30A inlet with 3.6kW transformer.

The lithium house bank and big inverters change everything.

[s/v Jedi]

Originally Posted by goboatingnow

WHy no RCBOs ( ELCOs) though ?

At the shore power inlets I have no problem with those and would recommend them. For the 30A I don’t need one because of the very short distance between inlet and transformer and for the 50A inlet, which has a Yandina (also on the forum) galvanic isolator, I first have what I call surge suppressor installed. It’s also an energy management system that doesn’t even pass power through unless it qualifies to much more than what a RCBO does. It is approved for mobile applications and I went that route because of being in thunderstorm alley often ;-)

Pic showing short leads from inlet to surge suppressor. On its output Neutral is dropped as it’s only needed for the power management tests.

[goboatingnow]

I first have what I call surge suppressor installed. It’s also an energy management system that doesn’t even pass power through unless it qualifies to much more than what a RCBO does.

sounds interesting , links to the product?