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chris-saunders avatar image
chris-saunders asked

Shore Power - 30A & 50A - How to?

Hi,

I am in the process of refitting SV ZoZo, a CT54. I am in the process of designing the new shore power connections and wanted some advice. I intend to have a single 240/50A shore power inlet on the boat which, with adaptors, can be hooked up to either 120v, 30A or 240v, 50A. I have a victron Isolation autotransformer (3600W) which will work fine for 120v 30A or 240v 15A giving me 240v out at approx. 13-14A. However, if I plug into 240v 50A I assume that the isolation transformer will not provide more than the 13-14A. Firstly, will I damage the isolation transformer if it is connected to a 50A supply or will it only draw 15A? Secondly, if this will limit the current I can draw from the shore supply I would like to add a 3P rotary selector switch to the supply before the isolation transformer to bypass the transformer and route the earth through a galvanic isolator to my Quattro (24/5000/240). If the selector switch output goes to the quattro then the supply will go across the isolation transformers output. Will this damage the transformer? Any better solutions?

Thanks, Chriszozo-ac-source-schematic.jpg

Isolation Tranformer
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2 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

The transformer will not actively limit the current.
It is rated for the current mentioned in the datasheet and if you pull more current it will damage/destroy the transformer.
So you have to add a fuse/breaker rated to the current of the transformer before it to prevent that.

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chris-saunders avatar image
chris-saunders answered ·


Thank you for your reply. So, if I connect the rotary switch after the isolation transformer then presumably only a minimal current will pass through the transformer (no load current) if a 240v 50A supply is connected to the input with switch position 2 selected?

The shore power input feeds the isolation transformer and the rotary switch via a 60A RCD breaker. Only when position 1 of the isolation transformer is selected will any significant curent pass though it.zozo-ac-source-schematic-11.jpg


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