Chapter 8 Connecting Power; Power Cable Selection - KVH Industries TracPhone F55 Installation Manual

Connecting Power

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 mΩ.
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 mΩ ship source impedance is measured, only 200 mΩ is left for power
cable loop resistance, since the total source impedance should be below
250 mΩ (250 mΩ - 50 mΩ = 200 mΩ).
Note
If the total source impedance is higher than 250 mΩ, the terminal
may start to On/Off oscillate.
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.
Chapter 8
8
37