KVH Industries TracPhone F55, Installation Manual

Page: 59 / 157

37
Chapter 8
888
Connecting Power
8
8.1 Power cable selection
The length of the BDU power cable depends on the type of cable used and the
source impedance of the ship’s 24 V DC installation. It is required that the total
source impedance at the BDU does not exceed 250 m
Ω
.
Select a power outlet from the ship’s 24 V DC system, and measure the source
impedance of the ship installation as described in
Measuring the Ship Source
Impedance on page 93 in Appendix C.
If a 50 m
Ω
ship source impedance is measured, only 200 m
Ω
is left for power
cable loop resistance, since the total source impedance should be below
250 m
Ω
(250 m
Ω
- 50 m
Ω
= 200 m
Ω
).
For further recommendations on power cable selection, see the appropriate
section on the next page, depending on which power connector the BDU is
fitted with:
• BDU fitted with the old 4-Port power connector: See section 8.1.1 Old 4-port
power connector .
• BDU fitted with the new Sub-D power connector: See section 8.1.2 New
Sub-D power connector .
Note
If the total source impedance is higher than 250 m
Ω
, the terminal
may start to On/Off oscillate.