galvanic isolators

[daveperce]

Last season, after using shore power failrly regularly, I discovered that the anode attached to the shaft had all but corroded away over a matter of only 4 months. Whilst I am pleased that it is obviously doing its job, I would prefer it to last an entire season! I have heard of a zinc protection device which is wired into earth on the shore power cable and helps to slow down the speed of galvanic action. They seem to cost about £50 - £60. Does anybody have any knowledge of their application/installation ?

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[pvb]

How it works...

There a good explanation of how galvanic isolators work on the <A target="_blank" HREF=http://www.yandina.com/galvanicIsolator.htm>Yandina website</A>. It also tells you how to make your own.

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[qsiv]

Re: How it works...

I have to say that it doesnt quite meet my expectation of a galvannic isolator.

Our galvannic isolator (from Mastervolt) is a large transformer that COMPLETELY decouples the boat from the shore electrics (well it is connected by the magnetic flow in the transformer core). This removes absolutely all possibility of any stray DC elements acting over time. With an aluminium boat we are perhaps a little more cautious than some, but the device shown only appeared to try and isolate the earth wire.

Our isolator (a 5Kw affair), weighs in at over a 100Kg but is well worth the peace of mind it brings.

In principle any 1:1 transformer that will sink the required power would do - but the marine versions tend to have belt and braces insulation and fixings - a domestic transformer wouldnt be expected to be thrown around like a yacht.

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[pvb]

Isolation transformers...

What you've got is generally called an "isolation transformer" and is probably about £750 worth. If I had an aluminium boat, I'd fit one of those too.

Galvanic isolators don't give full isolation, they just work to stop stray currents eating away the anodes so quickly. That's why they're much cheaper.

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