Selection Of Power Supply Cable - Furuno FS-1575 Service Manual

1.2.2 Selection of Power Supply Cable

Select a power supply cable that allows power loss in the power supply cable, i.e.,
voltage drops in the cable, to fall within the range of 3% to 5%.
Cable selection is determined by current passing through the cable and the cable
length.
Fig. 1.2.2 shows a graph for 5% voltage drop in individual cables. For example,
supposing that current passing through the cable is 20A and the cable length is 30 m,
DPYC-25 should be selected. However, be noted that voltage drops are caused not
only in the cable, but also in power supply connection terminals, power supply unit,
and internal wirings of devices. As a result, it is advisable to select a power supply
cable slightly larger than a calculated size.
Voltage drop in cable: e = (K×I×L) / 1000
Cable length: L = (1000 ×e) / (K×I×r)
- K = Coefficient (Single phase/DC: 2, three phase: √3)
- I = Current (A)
- R = Resistance per 1-km cable (ohm/km)
- L = Cable length (m)
Current (A)
1.2.3 Miscellaneous
CONFIDENTIAL (internal use only)
This confidential document is used only by FURUNO authorized persons.
It is strictly prohibited to reproduce the document in whole or in part without prior written permission of FURUNO.
Fig. 1.2.2 Voltage Drops in Cables:5%
1-7
1.2 Installations
Cable length (m)