Furuno FELCOM251, Installation Manual

Page: 49 / 122

3. CONNECTING POWER
3-2
3.2 Power Cable Selection
3.2.1 Source impedance
The length of the power cable depends on the type of cable used and the source im-
pedance of the DC power installation in the ship.
The maximum allowed source impedance depends on the usage of the power range
of the Communication Unit DC input (12 to 24VDC (-10% to +30%); 14 A to 5.5 A).
Select a power outlet from the DC system and research the source impedance.
Note: If the total impedance is higher than the limits stated in this section, the Com-
munication Unit may become unstable and start to on/off oscillate.
The total impedance is made up of the source impedance of the ship power supply
plus the impedance of connected cables including connectors and joints where cables
are extended.
For further recommendations on power cable selection, see section 3.2.2.
3.2.2 Power cable recommendations
Overview
The Communication Unit is delivered with a power cable, which can be extended ac-
cording to the recommendations in this section.
• When extending the power cable, positive and negative supply wires must be in-
stalled closely together side by side to keep cable inductance low.
• Ensure that cable inductance for the selected cable at the desired length is below
the 50

H requirement.
The power cable contains the following wires:
Power cable pinout
Colour of wire
in power cable
Pin number in
connector
Function
Red A1 Vin+
Black A2 Vin-
Black 1 not connected
Green 2 not connected
Brown 3 not connected
Red 4 not connected
Orange 5 not connected