Chapter 12 Communication Power Supply
12-5
(Example 2) When the total power consumption value varies in each section
Total power consumption value of section 1 = 1.4 A + 1.0 A + 1.0 A = 3.4 A
Total power consumption value of section 2 = 0.1 A + 0.15 A + 0.1 A = 0.35 A
Maximum allowable current value of section 1 = 2.01 A (from Figure 12.1)
Maximum allowable current value of section 1 = 2.01 A (from Figure 12.1)
From the summations above, it can be determined that the current capacity is insufficient in section 1.
(Action 2) Connect the communication power supply so that the total power consumption is divided equally
between each sections.
Total power consumption value of section 1 = 1.4 A + 1.0 A = 2.4 A
Total power consumption value of section 2 = 1.0 A + 0.1 A + 0.15 A + 0.1 A = 1.35 A
Maximum allowable current value of section 1 = 2.562 A (linear interpolation between 100 m to 150 m)
Maximum allowable current value of section 2 = 1.722 A (linear interpolation between 150 m to 200 m)
In this configuration, the total power consumption is within the maximum allowable current value in
each section. Furthermore, it can be determined that power can be supplied to all the devices on the
network.
Device
1.4A
Device
1.0A
Device
1.0A
Device
0.1A
Device
0.15A
Device
0.1A
120 m (section 1)
180 m (section 2)
Communication
power supply
Termination
resistor
Termination
resistor
Trunk line (thick cable)
Trunk line (thick
150 m (section 1)
150 m (section 2)
Device
Device
Device
Device
Device
Device
1.4A 1.0A 1.0A
0.1A 0.15
0.1A
Termination
resistor
Termination
resistor
Trunk line (thick cable)
Trunk line (thick cable)
Communication
power supply