JRC JMA-5212-4, Installation Manual

Page: 32 / 156

3-7
Caution
Incorrect connection between the ship's power supply or the rectifier and the
power cable may cause an equipment failure.
Selecting a cable when a long power cable is required
The input voltage to an indicator is determined by subtracting the voltage drop up to
the power cable from the ship's power supply voltage.
Therefore, if the power cable is too thin or too long, the voltage drops substantially,
preventing the radar from functioning at its full capacity. Use the following guideline
for selecting a power cable.
(a) Take the voltage fluctuation rate into consideration when determining a voltage
(Vs) value of the ship's power supply.
(b) Use the following formula for calculating a voltage drop (V).
V=2LRKI
L : Cable length
R : Direct current resistance at 20C (/m)
K : Conductor resistance temperature counting (=1.22)
I : Maximum peak current (A)
(c) Various cable direct current resistances (R) and allowable current (Imax)
Cable type R (20°C) Imax
(45°C continuously)
CVVS2 x 1.25 16.7 /km 13A
CVVS2 x 2.0 9.42 /km 19A
CVVS2 x 3.5 5.30 /km 26A
Provide a sufficient extra current value to Imax when selecting cables.