which galvanic isolator

[kizzyben]

I am about to fit shore power to my boat (Sadler 29) complete with a galvanic isolator.
I have seen Nigel Calders reply to a recent question on an isolation problem in which he said "As far as I know all galvanic isolators currently sold do have a capacitor"
I have come across one which states that "some Isolator manufacturers attempt to by-pass the AC leaks by fitting a capacitor inside the Isolator. This is not practical as it is impossible to fit a single capacitor to by-pass the varying frequencies of AC which may be present".
They market a 70 amp Isolator which they claim controls all galvanic problems up to 2.4 volts.

My question is: which would you consider the safest to use, one with or without a capacitor.

Thanks

 

[Bodach na mara]

This link
http://www.yandina.com/galvanicIsolator.htm
will answer your question. A capacitor is not necessary or desirable, as the function of the isolator is to prevent currents from flowing unless the voltage is greater than that developed by an electrolytic cell. They consist of a high current bridge rectifier, which will allow the AC to flow anyway if there is a short to earth.

 

[VicS]

If you have not already seen it this page on the Yandina.com site is worth reading
http://www.yandina.com/galvanicIsolator.htm Click on the heading in it to go to the page about capacitors.

Yandina appear to offer a capacitor as an optional extra. I have not looked into it but I assume that means something that can be retro fitted.

There used to be insructions in the project section for making a basic GI but it appears to have been axed.

The size of the capacitor will depend upon the frequecy of the AC it is to pass. Low frequencies will need a large value capacitor while high frequencies will need a small one. If both are present then it may be necessay to use high and a low value ones in parallel but I dont understand where frequecies other than 50Hz will be coming from

Sorry Ken, slow typing again.

 

[pvb]

DIY galvanic isolator...

The DIY instructions are still on the Yandina site - see here.

 

[pvb]

Safety...

[ QUOTE ]
My question is: which would you consider the safest to use, one with or without a capacitor.

[/ QUOTE ]I'd consider both types to be safe. There is an argument in favour of having a capacitor, as long as it's big enough to be of real use. The people who say it's not practical to fit a capacitor presumably don't make one with a capacitor (might this be Safeshore Marine?).

Sterling market the ProSafe galvanic isolator, which does have a capacitor.

 

[VicS]

Re: DIY galvanic isolator...

[ QUOTE ]
The DIY instructions .......................

[/ QUOTE ] Thanks. I was looking for it a week or so ago. I still can't see how one would find it from the menus etc.

It's of academic interest really. I don't have shore power or any metal bits below the waterline so I'm not actually thinking of making one.


Would you belive it I actually have a note of its URL all the time!!!!!