Power Cable Selection - KVH Industries FleetBroadband FB250 Installation Manual

Chapter 3: Connecting power

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 impedance of the DC power installation in the ship.
The maximum allowed source impedance depends on the usage of the power
range of the terminal DC input (10.5 - 32 V DC; 14 A - 5.5 A).
Select a power outlet from the DC system and measure the source impedance
of the ship installation as described in the next section.
Note
If the total impedance is higher than the limits stated in this section,
the terminal 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 Power cable
recommendations on page 56.
3.2.2 Measuring the ship source impedance
Select a power outlet from the ship 24 V DC or 12 V DC system, and measure
the source impedance of the ship installation as described below.
1. Measure the voltage without load (R.var disconnected).
2. Set the current to e.g. 1 A by adjusting R.var.
3. Measure the corresponding voltage change.
54 Power cable selection