COBHAM Sailor 250 FleetBroadband, Training Manual, Page: 131 / 270

121
SAILOR FleetBroadBand
Training Manual
4
4.10 Grounding
Figure 4-43
DC Negative
Actually not a ground but a current-carrying conductor which
carries the same current that flows in the positive conductor. The
DC Negative may be electrically connected to seawater (at one
point only, via the engine negative terminal though the shaft and
the propeller) or left completely floating.
Lightning Ground
Ground potential immersed in seawater. Provides a path to ground
lightning strike energy. Please note that this is not a functional part
of any other electrical system. Bonding arrangement that ensures
equal electrical potential for all dissimilar underwater metal parts
and provides galvanic protection by means of sacrificial anodes.
Corrosion System Ground
Ground potential immersed in seawater (typically the hull for
steel and aluminum vessels). Serves as safety ground (protective
earth) thus preventing shocks or electrocution in the event of a
fault situation.
AC Ground (Protective Earth)
Underwater ground potential that is capacitively coupled to
seawater ground. Typically numerous pieces of bonded underwater
metal parts such as keel (isolated), water tank, engine block etc.
will act as a capacitive RF ground (that is; no DC connection to
seawater). Often referred to as “counterpoise” for the SSB/HF
aerial system.
RF Ground (Capacitive)
Underwater ground potential that is electrically coupled to seawater
ground by means of a separate ground plate (e.g. Dynaplate).
Also referred to as “counterpoise” for the SSB/HF aerial system.
RF Ground (Electrical)
Underwater ground potential that is electrically coupled to seawater
ground by means of a separate ground plate (e.g. Dynaplate).
Also referred to as “counterpoise” for the SSB/HF aerial system.
NOTE!
Safety:
First of all grounding of the
system is required for safety
reasons. In the event of a
lightning strike at the antenna a
proper grounding of the system
will provide a low resistance
path to divert the strike
discharge to seawater.
ESD Protection:
The ESD protection circuits
in the terminal rely on proper
grounding of the system
in order to work properly.
Otherwise sensitive circuits
within the terminal might be
damaged due to ESD when
you are handling the
equipment.