Onboard Isolation Transformer vs Safety

[Ahmet Erkan]

Originally Posted by Ahmet Erkan

Hello dfelsent,
We are so lucky that one of the engineers who helped originate E11 is actually participating in this discussion and it was his recommendation for all to actively collaborate with ABYC technical board by making recommendations.
If you noticed, transmitterdan is recommending shore power grounding conductor to not be brought on board which is a big change from the current recommendations by ABYC so he should submit a complete technical data package describing what he is recommending be changed.
Since it is your belief that "drawings in the standard represent current industry best practices" thus there is no need for improvement, you could (if you like) add value and participate by critiquing other EE's recommendations and defend the current drawings in E11.
So why do you think the second ELCI that I am recommending to be added to E11 diagram 8 is not necessary?
Thank you Sir.
Ahmet

Ooops sorry.
I should have said, "Thank you Sir or Madam"

[transmitterdan]

Ahmet,

You put words into my mouth i did not say. I say again for the record, use the recommendations in ABYC.

My idea of removing shore ground was just to show you how to remove the possibility of shock hazard altogether. But I don’t think the risk is sufficiently high with ABYC drawings to warrant any change to the standard.

Again, the ABYC drawings are well thought out and correct. No change is needed IMO.

This thread should be deleted IMO.

[DotDun]

Originally Posted by transmitterdan

....
This thread should be deleted IMO.

vote #2 !!!!

[Ahmet Erkan]

Originally Posted by transmitterdan

Ahmet,

You put words into my mouth i did not say. I say again for the record, use the recommendations in ABYC.

My idea of removing shore ground was just to show you how to remove the possibility of shock hazard altogether. But I don’t think the risk is sufficiently high with ABYC drawings to warrant any change to the standard.

Again, the ABYC drawings are well thought out and correct. No change is needed IMO.

This thread should be deleted IMO.

transmitterdan,
You are either recommending removal of the earth ground from the transformer or not. You can't have both. So which is it?

Ahmet

[Ahmet Erkan]

Originally Posted by SteveWrightNZ

Do not bring the earth wire anywhere near the yacht - don't even connect it at the shore power plug.

What is quoted above is an unsafe recommendation even if you own the most reliable isolation transformer in the world.
An isolated ground AC power system cannot be implemented on board a vessel if the earth ground is not brought on board.
Not only the earth ground conductor but the shore power neutral must be brought aboard so that a common marina failure known as "open ground" can be verified not to exist.
The earth ground is used by the on board isolated ground system control relays/monitors to verify the isolation barrier in the transformer. By the way, in a isolated ground system both the phase to ground and neutral to ground have high impedances that are continuously monitored so the E11 diagrams connecting the neutral to hull ground have eliminated any possibility of an isolated ground system.
OK I will put all this on paper and make it available for the interested with a link.
By the way, what I am sharing here are all based on scientific theory plus my own 45+yr design experience at square D, Bell labs and a reputable defense contractor company. So if a moderator gets triggered by DotDun or transmitterdan and deletes this thread claiming technical errors that will be a shame.
I would like to share with you at least the response to my change request to E11 diagrams.
In my mind, the redlines presented to ABYC technical director are so black and white (no pun intended) that if he agrees with all the CF experts who have been pushing back on just about everything I said here and claims the diagrams in E11 are just fine.....Well we will cross that bridge if we ever get there :-)
Thanks
Ahmet

[transmitterdan]

Ahmet,

Are you unfamiliar with the concept of discussing and debating ideas? This is an internet discussion forum.

For the record, I only recommend using the ABYC recommended configurations.

However, we are all free to discuss other configurations and share opinions. You know my opinion of the proposal to use an isolation transformer with shore ground going to the boat metal thus requiring a GI. In my opinion it’s not a terribly useful configuration in case that was not clear.

[DotDun]

All,

Beware that if you decide to view Ahmet's drawings on the link he provided, they are not on a CF site and you will be giving up some privacy in that he will then be able to see your iCloud username. You have to decide if this privacy breach is something you accept.

IMO, it hinges on breaking a CF rule, "Do not use posts to promote your blog", as these drawings are his proposal, his blog, to ABYC, they are his opinion only, and it appears he is trying to build a groundswell of support for his proposals at ABYC via these drawings. There is no reason Ahmet can't post his drawings on CF, so his motive for using a site outside of CF should make you suspicious.

[CharlieJ]

Here is a trick question:

Q: What do you call an isolation transformer connected as put forth by the OP?

A: Not an isolation transformer!

[Pelagic]

Mine is labeled

[transmitterdan]

Originally Posted by CharlieJ

Here is a trick question:

Q: What do you call an isolation transformer connected as put forth by the OP?

A: Not an isolation transformer!

Right. In the industry they call it a polarization transformer. It only serves to correct polarization issues caused by incorrectly wired shore side pedestals.

See for example: http://www.charlesindustries.com/mar...MR6T-1_PR2.pdf

I note that, according to this installation guide, the OP's suggested configuration is ABYC compliant. And it obviously is but it is not preferred since it requires a galvanic isolator which is the prime motivation to install an isolation transformer in the first place.

Perhaps the only reason to dislike the isolation configuration, in favor of the polarization configuration, would be if one owned a galvanic isolator factory...

[Pelagic]

Personally I think we have enough polarization in this thread

[Ahmet Erkan]

Originally Posted by DotDun

All,

Beware that if you decide to view Ahmet's drawings on the link he provided, they are not on a CF site and you will be giving up some privacy in that he will then be able to see your iCloud username. You have to decide if this privacy breach is something you accept.

IMO, it hinges on breaking a CF rule, "Do not use posts to promote your blog", as these drawings are his proposal, his blog, to ABYC, they are his opinion only, and it appears he is trying to build a groundswell of support for his proposals at ABYC via these drawings. There is no reason Ahmet can't post his drawings on CF, so his motive for using a site outside of CF should make you suspicious.

Thank you for your inputs DotDun,
Couple of pieces of wrong information.
* You do not need to use your icloud username just enter a number or letter as a workaround.
* Not a blog promotion, just a means to safely share a document (engineering change request ECR) submitted for ABYC review. IMO this ECR is of interest to many boaters.
Now I will post the ECR from the menu above if that is what you prefer. (First time uploading a file to CF so not sure if it is going to work)
OK I tried to load the editable word file but got an error message.
Now I will try a pdf version. Here goes.

No joy. Exceeded the 400kb CF size limit.
I could divide it into smaller files but really icloud has the best virus protection and safety.

Let me know if you are OK now.
Ahmet

[Ahmet Erkan]

Originally Posted by CharlieJ

Here is a trick question:

Q: What do you call an isolation transformer connected as put forth by the OP?

A: Not an isolation transformer!

Here is another trick question:

Q: What do you call an isolation transformer connected as put forth by ABYC E11 diagrams 6 and 7?

A: A miswired isolation transformer.

[transmitterdan]

Originally Posted by Ahmet Erkan

Here is another trick question:

Q: What do you call an isolation transformer connected as put forth by ABYC E11 diagrams 6 and 7?

A: A miswired isolation transformer.

Here is a real non-trick question.

Can you provide any example of anyone injured from a system wired per ABYC E11? If not, then explain why there has never been an injury.

[CharlieJ]

Post # 163: Wrong answer. An "isolation transformer" wired as you recommend is non-compliant with the ABYC Standard and is not an isolation transformer in that it does not isolate the mains safety ground system from the vessel's safety ground system which is the primary reason for installing an "isolation transformer".
Post # 160: Correct answer.. Couldn't have said it better myself.