Isolation Transformers.
Galvanic isolation on shore power
Through the protective earth of the shore connection, the boat is electrically connected to the marina and to other boats. If different metals lie in the same water, a galvanic current flows through this connection and slowly dissolves the less noble metal – drive, saildrive, propeller or, on metal yachts, the hull. Galvanic isolators and isolation transformers interrupt this circuit.
All products. 2 items.
Galvanic isolation – isolation transformer and galvanic isolator
In brief: The galvanic isolator blocks the small corrosion currents in the protective earth. The isolation transformer separates the onboard system completely from the shore supply. The range includes the GI galvanic isolator from philippi and the Mass GI 3.5 isolation transformer from Mastervolt.
Isolation transformer
Isolation transformers with a 230/230 V ratio galvanically separate the 230 V onboard system from the shore supply. On the boat side a new network isolated from shore is created, which is protected by a downstream residual current device. Devices with input voltage switching also allow a 230 V onboard system to run on 115 V shore power.
Galvanic corrosion
Two different metals in the same electrolyte form a voltage source because of their different electrochemical potentials. If they are conductively connected, current flows until the metal with the lower potential is consumed. Yachts with a metal hull on shore power are particularly at risk – for example an aluminium yacht next to a steel sheet pile wall or a steel yacht. But the drive of a GRP boat can also be attacked in this way. More on this on the topic page Shore power on boats.
Frequently asked questions. Answered briefly.
What does a galvanic isolator do?
A galvanic isolator such as the philippi GI sits in the protective earth of the shore connection and blocks the small direct currents that flow between different metals in the harbour water and attack the drive or hull. The protective earth remains continuous for fault currents. It is the simple and economical solution against galvanic corrosion via shore power.
When is an isolation transformer the better choice?
An isolation transformer completely separates the onboard system from the shore supply, including the protective earth. On board, a separate network isolated from the shore is created, which is again protected by residual current devices. This is recommended especially for steel and aluminium yachts and boats often in foreign harbours. The Mastervolt Mass GI 3.5 delivers 3500 VA.
Does galvanic corrosion also affect GRP boats?
Yachts with metal hulls whose protective earth is connected to the harbour via the shore connection are most at risk. But on GRP boats too, the saildrive, propeller and shaft can be attacked galvanically via the shore power earth. An isolator or isolation transformer interrupts this circuit; the sacrificial anodes of the drive are still needed.
Which version do I need, GI 16 or GI 32?
That depends on the fuse rating of your shore connection: the GI 16 galvanic isolator is designed for 16 A, the GI 32 for 32 A. Both have a 5000 A peak current, two M6 studs and a waterproof potted anodised aluminium housing of 200 x 120 x 60 mm. The isolator is installed in the protective earth.