3-3
Section
Sharing the Communications Power Supply
31
Thick Cable
Distance (m)
0
25
50
100
150
200
250
300
350
400
450
500
Max. 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
Max. current (A)
Distance (m)
8
7
6
5
4
3
2
1
0
0
Thin Cable
Distance (m)
0
10
20
30
40
50
60
70
80
90
100
Max. current (A)
3.00
3.00
3.00
2.06
1.57
1.26
1.06
0.91
0.80
0.71
0.64
Max. current (A)
Distance (m)
3
2
1
0
0
Verify the Items 1. to 3. below for each node located in the same direction viewed
from the power supply. Therefore, if nodes are located on both sides of the pow-
er supply, these items must be verified for all nodes located in each direction.
1, 2, 3...
1. Find A, the total current consumption of all the nodes to which communica-
tions power is to be supplied.
2. Using the graph compute B, the maximum current flow in each cable from
the power supply to the end of the trunk line according to the types of cables
(thick or thin).
3. Compare the values found in steps 1. and 2., above. If the first value (A) is
less than the second (B), this shows that power supply specifications are
met and power can be supplied to all nodes at any point in the network.
Note Be sure to refer to the correct graph because the maximum current
flow is different for thick and thin cables.
If the second value (B) is less than the first (A), use the following procedure to
locate the communications power supply.
•
Locate the communications power supply in the center of the network and the
nodes to both sides of it.
Determining the Best
Location of the Power
Supply from a Graph
Countermeasures
