Tottie
New Member
Hi. I'm a live aboard in Plymouth and have been advised to fit a galvanic isolator to my Twister. Does anyone have any opinions on these, either way?
Thanks
Thanks
Galvanic isolator?
- Thread starter Tottie
- Start date
Mistroma
Well-Known Member
I fitted one as it wasn't expensive and I'd be connecting to power is various countries. It seemed like a good safeguard. I bought one with some LEDs to warn of some failure modes and also test it annually. Worthwhile if you connect to shorepower reasonably often and I'm guessing that is the case.
Anodes seem to last a little longer but still shrink at a reasonable rate. It isn't doing any harm and may well have saved problems.
I would have preferred an isolation transformer but they were much more expensive. Sod's law came into play and I saw someone selling them at very reasonable prices just after I'd installed it. Unfortunately it was ages ago and I can't remember seller's address.
Anodes seem to last a little longer but still shrink at a reasonable rate. It isn't doing any harm and may well have saved problems.
I would have preferred an isolation transformer but they were much more expensive. Sod's law came into play and I saw someone selling them at very reasonable prices just after I'd installed it. Unfortunately it was ages ago and I can't remember seller's address.
l'escargot
Well-Known Member
If you search the forums for "galvanic isolator" you will find quite a lot of information and discussion.
http://www.ybw.com/forums/search.php?searchid=154276
Basically a GI is only necessary if your DC and AC circuits are bonded - the 12v negative connected the 240v earth - if the two systems are totally separate a GI is of no benefit.
http://www.ybw.com/forums/search.php?searchid=154276
Basically a GI is only necessary if your DC and AC circuits are bonded - the 12v negative connected the 240v earth - if the two systems are totally separate a GI is of no benefit.
Last edited:
Mistroma
Well-Known Member
It appears that technology has moved in favour of fitting an isolation transformer instead of a galvanic isolator.
http://www.smartgauge.co.uk/galv_tran.html
When I first looked at fitting a galvanic isolator it seemed to be a reasonable choice, especially as isolating transformers were very expensive. It looks as if benefit from a GI is less than it used to be in the past.
http://www.smartgauge.co.uk/galv_tran.html
When I first looked at fitting a galvanic isolator it seemed to be a reasonable choice, especially as isolating transformers were very expensive. It looks as if benefit from a GI is less than it used to be in the past.
sailvayu
New Member
A galvanic isolator will prevent DC current from coming into your AC system through the shore ground wire. A DC current is set up when there is an imbalance between you and other boats sharing the same shore ground. DC is what causes most corrosion. This is one of those subjects that often gets a lively conversation going but I would say yes install one it won;t hurt and could save your underwater metal.
Thanks
Capt. Wayne Canning, AMS
www.projectboatzen.com
Thanks
Capt. Wayne Canning, AMS
www.projectboatzen.com
Tottie
New Member
GI
OK .... thanks for that. I just get different advice from so many people about what I need ... This is helpful though
OK .... thanks for that. I just get different advice from so many people about what I need ... This is helpful though
Tony Cross
Well-Known Member
I've found the advice given at http://www.smartgauge.co.uk/galv_tran.html to be very useful in the past. Lots of other good stuff on this website too.
l'escargot
Well-Known Member
You will on here too - post the same question in the PBO Reader to Reader section and watch...
rivonia
Well-Known Member
We have a CAT and fitted galvanic Isolaters one to each engine bay. The corrosion of the Annodes stopped and instead of only lasting around about a year they are still going strong after two years. We are in the Med in a Marina.
Peter
Peter
rivonia
Well-Known Member
We have a CAT and fitted galvanic Isolaters one to each engine bay. The corrosion of the Annodes stopped and instead of only lasting around about a year they are still going strong after two years. We are in the Med in a Marina.
Peter
Peter
Mistroma
Well-Known Member
Last edited:
RichardS
N/A
I don't quite get that (either time!) Peter.
Presumably you only have one shore power cable running through to the battery charger. As the GI connects into the shore cable, why would you need a GI on each engine?
Richard
tcm
...
galvanic isolator - good idea, cheap. Isolation transformer pain in the a*** threw it over the side, far too picky a machine.
Mistroma
Well-Known Member
Interesting, I'd always heard that an isolation transformer was the better option and that a GI was a simple, low cost, but less effective option. The Smartguage link in my previous post concluded that GIs were becoming less effective now that switch mode power supplies were commonplace.
I had not heard of many problems with isolation transformers. What sort of problems did you find? e.g. Power regulation issues?
Not that I'm planning to replace my GI. It seems to work and anode don't vanish in a short time. Most of my AC items aren't switched mode anyway (heater, immersion element, kettle, toaster iron etc.) Microwave isn't used for long periods. That just leaves TV, laptops and phones but these tend to be on 1 or 2 at a time for an hour a day. The Smartguage article indicates that 1 or 2 switched mode supplies should not cause huge problems.
Last edited:
rivonia
Well-Known Member
Hi Richard,
If there is any earth leakage in a marina (there always is) then the boats without the G I's will get corosive effects, which usually means the annodes and a worst case scenario the engine.
The G I does NOT connect to the shore cable. We have an isolated ring main on board and it works off that all earthed and very efficient.
I am not an electrician and the G I's were fitted proffesionaly.
Hope this helps
Peter
RichardS
N/A
Many thanks Peter
My understanding (which may be completely wrong as my testing of my GI with an ohm-meter simply served to confuse me!) is that the galvanic current, if there is any, is only a problem if it can leak to earth, which it can only do down the shorepower cable - presumably down the earth wire. The GI therefore fits into the shorepower earth cable to stop any galvanic DC voltage to earthing itself but still allow dangerous higher voltages, which would result from an AC fault, to be earthed safely.
I'm going to use my voltmeter again next time I'm on the boat to try and understand all this better!
Richard
My understanding (which may be completely wrong as my testing of my GI with an ohm-meter simply served to confuse me!) is that the galvanic current, if there is any, is only a problem if it can leak to earth, which it can only do down the shorepower cable - presumably down the earth wire. The GI therefore fits into the shorepower earth cable to stop any galvanic DC voltage to earthing itself but still allow dangerous higher voltages, which would result from an AC fault, to be earthed safely.
I'm going to use my voltmeter again next time I'm on the boat to try and understand all this better!
Richard
rivonia
Well-Known Member
The system on the YBW is not allowing me to reply correctly-it keeps saying that my message is too short? so it will be all mixed up now that is if it goes through at all.
Peter
vyv_cox
Well-Known Member
Your understanding is the same as mine. The function of the galvanic isolator is to prevent adjacent boats from being linked galvanically through their earth wires. Without it various preferential galvanic reactions can take place, e.g. your anodes protecting next door's prop, or worse, your prop protecting theirs!
Tottie
New Member
I'm hooked up to the mains all the time ..... time to do some shopping around I think. Thanks for all the advice. I'm new to this live-aboard thing
