Hamilton Jet HJ212, Инструкция по установке и обслуживанию

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Precautions Against Corrosion
Installation and Service Manual
D.C. Systems
The DC system should use two insulated "normally conducting" wires, a positive and a negative.
The negative must not run through the frame of any unit, through the hull of the boat, or through the
bonding system. Do not use an earth return system.
It is recommended that engine starter motors or other DC motors should be the two wire type with an
insulated negative terminal rather than having their chassis connected to the battery negative. This is to
ensure starting currents do not pass through the earth bonding system.
In smaller vessels, it is common to use negative ground engine systems in which the starter motor, starter
solenoid, and alternator are single pole devices using the engine block as the local return conductor. In this
situation, it is important to connect the engine block to the battery negative with a suitably sized heavy
duty cable.
In installations with two engines and two battery banks with cross-connect starting capability, there must be
two suitably sized heavy duty conductors between the engines.
A.C. Systems
Vessels with both AC and DC circuits, must for safety reasons, use a separate earth wire for the AC system.
If a vessel with bonded aluminium jets is connected to a dock supply, without the protection of an isolation
transformer or a galvanic isolator, the dock potentials through the earth wire will cause the aluminium to
corrode. This will happen at a much greater rate than that experienced in normal sea water regardless of
whether the aluminium is protected by anodes or not.
Shore Connections
Using an Isolating Transformer
If using AC shore supply, install an isolating transformer on board at the incoming line to preventing
potentially serious galvanic or stray current corrosion.
When an isolating transformer is used, there must be no connection between the shore supply earth and the
vessels earth bonding system. The primary winding shield is earthed to shore, while the secondary winding is
grounded on board the vessel. Only one side of the secondary winding is grounded on the secondary side of
the transformer and the vessel’s grounding circuit is tied in at this point.
There must be no DC electrical connection between the shore supply and the on board AC circuit.
Further information (including circuit diagrams) can be found in American Boat and Yacht Council (ABYC)
publication E-11 AC and DC electrical systems on boats.
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