Hitachi HIDIC EH-150 Applications Manual page 95

(Example 2) When the total power consumption value varies in each section
Trunk line (thick cable)
Termination
resistor
Device
1.4A
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.
Trunk line (thick cable)
Termination
resistor
Device
1.4A
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.
150 m (section 1)
Device Device
1.0A 1.0A
Communication
power supply
120 m (section 1)
Device
1.0A
Communication
power supply
Chapter 12 Communication Power Supply
150 m (section 2)
Trunk line (thick cable)
Device Device
0.1A 0.15
180 m (section 2)
Trunk line (thick
Device Device Device
1.0A 0.1A 0.15A
12-5
Termination
resistor
Device
0.1A
Termination
resistor
Device
0.1A