Power cable selection
5-2 Chapter 5: Connecting power 98-133966-G1
5.2 Power cable selection
5.2.1 Source impedance
The maximum 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 (Start up voltage: 22 VDC
guaranteed, operating range: 20 – 32 VDC; 23 A – 14 A).
Select a power outlet from the DC system and measure the source
impedance of the ship installation as described in the next section.
For further recommendations on power cable selection, see Power
cable recommendations on page 5-3.
5.2.2 Measuring the ship source impedance
Select a power outlet from the ship 24 VDC 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.
Example: 1 A and 50 mV. Source impedance: 50 mV/1 Amp = 50
mOhm.
Note
If the total impedance is higher than the limits stated in
section 5.2.3, 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.
Figure 5-1: Measuring the ship source impedance
SAILOR900TM.book Page 2 Monday, September 16, 2013 11:01 AM
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