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TECHNICAL BACKGROUND
Using an isolation transformer
The risk of corrosion may mean you do not wish to
fit your protective earth onto the hull of your boat.
However, to ensure your power system is safe you will
need to install an isolation transformer.
With an isolation transformer, the earth wire remains
within the power cable for safety reasons but is not
connected to the boat. The phase and the neutral of
the power connection will instead be connected to
the primary (shore) side of the transformer, which will
‘convert’ the voltage to the same or, if necessary, a
different voltage.
A new phase and neutral, galvanically separated from
the shore, will be available on the secondary (boat) side
of the transformer.
The neutral will be connected to the onboard protective
earth system, which will now have nothing to do,
electrically, with the protective earth of the power
connection. This way the connection between two
different metals (or two different types of the same
metal) is blocked, eliminating the risk of electrolytic
corrosion.
The neutral connection of the other power suppliers
onboard, such as the generator and the inverter, also
needs to be linked to the onboard protective earth
system. An earth leakage switch is prescribed by directive
ISO 13297 for recreational craft up to 24 metres. The
various options for earth leakage switches and isolation
monitoring are subject to this directive.
Consult an expert for more details.
By the proper use of an isolation transformer, galvanic corrosion can be avoided.
ISOLATION
TRANSFORMER
ISOLATION
TRANSFORMER
AC GROUND WIRE
NO CURRENT FLOW
GROUND
ALUMINIUM
STERNDRIVE
BRONZE AND STAINLESS
STEEL HARDWARE
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