JRC JMA-3300 Series Installation Manual page 35

 Selecting a cable when a long power cable is required
The input voltage to the display unit 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.
 Take the voltage fluctuation rate into consideration when determining a voltage (Vs)
value of the ship's power supply.
 Use the following formula for calculating a voltage drop (V).
V=2LRKI
L: Cable length
R: Direct current resistance at 20°C (/m)
K: Conductor resistance temperature coefficient (=1.22)
I: Maximum peak current (A)
 Various cable direct current resistances (R) and allowable current (Imax)
Cable type
CVVS2×1.25
CVVS2×2.0
CVVS×3.5
Provide a sufficient extra current value to Imax when selecting cables.
Chapter 3 INSTALLATION OF THE DISPLAY UNIT
3.3 INSTALLATION OF THE POWER CABLE (CFQ-5436)
R (20°C)
16.7 /km
9.42 /km
5.30 /km
Imax (45°C
continuously)
13A
19A
26A
3-5
3