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.