 Hi folks Does anyone have a circuit diagram of a galvanic islolator, i think the current prices are crazy and would like to build my own with components bought individually.
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 Sorry, I have drawn a blank on this one. The Marine Electrical and Electronics Bible by John C Payne (Adlard Coles, my copy was published in 1995, £22.99, there may have been a new edition since then) has a diagram showing how to wire the galvanic isolator into the boat's electrics, but has no information of what there is inside the isolator or how it works. There is however a 15 page chapter on galvanic corrosion. It is the most thorough explanation/exploration of the subject I have found. Sorry not to be able to be more helpful
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Yes i am finding that there are numerous sources for fixing them but no actual circuits to be seen, i will live in hope, many thanks. PS. should be able to post some details by end of season on the work i have done to my MacWester26.
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Yes please, would love to have info on boat project!
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 | TMS Poloshirt winner |
08/07/08 22:39
 Not sure they re really a home build project, copied from an electrical forum: I was provided information on galavnic Isolators from Z-Guard Zinc anodes. They told me that these isolators must be tested at 5000 amps for 24 hrs and that the 30amp Isolator is good for European IMO standards and costs around £70 GBP. However the US standard is alot more stringent and the system requires monitoring aswell hence the price is also higher. Below are their details:
Z-Guard Zinc Anodes
Unit 203,
Tedco Business Works
Henry Robson Way
Station Road
South Shields
NE33 1RF
England
Tel: 0870 242 1973,
Fax: 0870 242 1974
Email: sales@z-guard.co.uk
website: www.z-guard.co.uk I ve not dealt with them so not a personal revcommendation but have had a quick look at their site and there seems to be some useful info there - maybe give them a call? W.
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thanks have emailed them and asked for a diagram.
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The circuit is basically two matched diodes back to back. anode to cathode, anode to cathode. The isolation is achieved by the diode forward breakdown characteristics. However they are quite high value types and usually expensive. If I get lucky I may find the circuit diagram among my junk box bits but right now I cant recall whereit is. Hope it points you in the right direction anyway. Martin
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| Edited: 16/07/08 22:38 |
OK Tafski Here is the circuit. Four diodes two this way -------l>l---l>l---- and two this way -------l<l---l<l---- Connected these in parallel together anode to cathode all in series with the earth line. No way of telling when they have gone open circuit or shorted. If you want to do the job properly use a 1:1 isolation transformer and dont connect the shore supply earth to the boat. Use the negative of the isolation transformer secondary as the boat earth. Even better never use a shore supply. Martin l
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If you have a big fat boat and weight doesn't matter there are ex computer bank isolation transformers about which provide the ultimate protection: they also feature a 110v tapping which is useful for pro power tools. About £100 and 30kilos. Very reassuring though on a steel/alloy/ferro vessel. Bond earth and neutral (on the boat side of the transformer!), fit a 30ma RCD & you have in effect your own power station. NO LIABILITY ACCEPTED FOR THE ABOVE ADVICE-please don't mess with 240v systems and salt water if your not completely au fait with it!
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