Ship Shore Power - Galvanic Corrosion

[davva]

I have searched a few of the topics on this site relating to this issue and would like to confirm the following.

If a ship's 3ph power system is unearthed, i.e. isolated neutral, then I understand that there is no requirement for an isolation transformer to be used when connecting to the shore power. Is this correct?

Also I have another query. Our ship's 690V power system is unearthed (as above), however we transform down to lower voltages for domestic supplies. We earth the star point of the secondary of this step down transformer so that we can run a 1ph & neutral supply to domestic consumers thus allowing savings in our distribution panels. Also it allows domestic consumers to trip on an earth fault. The shore supply will always connect to the isolated neutral 690V system. Do we have a problem with galvanic corrosion due to the earthed domestic supply system?

 

[itsmoked]

I think you have done it correctly. Hang on for further confirmation though.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

You should be OK. The corrosion issues arise when the same neutral is grounded onboard and onshore.

Bill
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