COBHAM Sailor 900 VSAT, Technical Manual

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Power cable selection
98-133966-G1 Chapter 5: Connecting power 5-3
5555
Connec
ting power
5.2.3 Power cable recommendations
5..2.3.1 Overview
The ACU is delivered with a power connector (PCB plug-in connector,
female plug, Weidmuller, Part number 1930050000), which accepts
wires up to AWG10/6 mm
2
.
• When installing the power cable, install positive and negative supply
wires closely together side by side to keep cable inductance low.
• Ensure that cable inductance for the selected cable at the desired
length is less than 50 uH. Approximately 50 m maximum length.
5..2.3.2 Calculating the maximum power cable length
For 24 VDC operation, the total impedance must be max. 60 mOhm
(R
max
), including the source impedance in the ship installation (R
source
).
The total impedance is made up of the following:
• Source impedance in the ship installation
• Impedance of the selected power cable
To calculate the maximum cable extension, do as follows:
1. First measure the source impedance in the ship installation as shown
in Measuring the ship source impedance on page 5-2.
2. Find the resistance per meter (Rwire) for the cable type you are going
to use.
For 4 mm
2
/AWG 11, the value is 4.8 mOhm/m at 55°C
For 6 mm
2
/AWG 10, the value is 3.8 mOhm/m at 55°C
For other cable types, refer to the data sheet for the cable.
The length is multiplied by 0.5 above because there are two
conductors in the cable.
If the TT-6080A Power Supply is used, use R
source
= 0 mOhm.
5..2.3.3 Examples for using the TT-6080A Power
Supply:
AWG11
max
=0.5 x (60 mOhm-0)/4.8 mOhm/m = 6.2 m
AWG10
max
=0.5 x (60 mOhm-0)/3.8 mOhm/m = 7.9 m
Maximum length
0 5

Rmax Rsource
–
 
Rwire
   
=
SAILOR900TM.book Page 3 Monday, September 16, 2013 11:01 AM