A Galvanic Isolator, Polarisation Cell or Decoupler is used to ensure that there is separation between the grounding of a shore power supply from the ship's electrical grounding.
Whenever a marine vessel is connected to AC shore power, a bimetallic circuit can be established which can cause corrosion of the vessel and its drive system components. Any time there is a direct bond between dissimilar metals in an electrolyte, a galvanic corrosion cell, is produced.
A galvanic isolator provides the following benefits:-
- Eliminates corrosion problems caused by the difference between the potential of the ship and the shore ground.
- Corrosion currents cannot travel between ships which are tied to the same shore ground.
- Prevents the risk of corrosion in key components of the propulsion system. Even relatively small levels of corrosion can seriously damage important propulsion components.
- Does not remove safety factor provided by grounding in the event of electric shock.
- In order to provide quotations for galvanic isolators we need to know the steady state AC current rating of the shore supply.