Chapter 12 Communication Power Supply
12-2
12.2 Layout of Communication Power Supply
Follow the procedure shown below when determining the position and number of communication power supplies
to be used.
1. Calculate the power consumption necessary for each device on the network.
2. Measure the total length of the network.
3. Calculate the maximum current capacity corresponding to the network distance and the cable type used.
See Figures 12.1 and 12.2 for how to calculate it.
4. If the power consumption calculated in step 1 above is lower than the maximum current capacity, any of the
positions to connect the power supply shown in Section 12.3 may be used.
5. If the power consumption calculated in step 1 above is greater than the maximum current capacity, it is
necessary to examine the position in greater detail in order to connect the power supply. For more
information, see Section 12.4.
M
axim
u
m
c
urr
ent
8
7
6
5
4
3
2
1
0
0 50
100
150
200
250
300 350
400
450
Length of network (m)
Figure 12.1 Maximum current capacity (thick cable)
Distance
(m) 0 25 50 100 150 200 250 300 350 400 450 500
Maximum
current (A)
8.00 8.00 5.42 2.93 2.01 1.53 1.23 1.03 0.89 0.78 0.69 0.63
Figure 12.2 Maximum current capacity (thin cable)
Ma
xim
u
m
current
3
2
1
0
0 10
20
30
40
50
60 70
80
90
Length of network (m)
Distance
(m) 0 10 20 30 40 50 60 70 80 90 100
Maximum
current (A)
3.00 3.00 3.00 2.06 1.57 1.26 1.06 0.91 0.80 0.71 0.64
