One Power Supply (Middle-Connected) - Parker H Series Installation & Service Instructions Manual

One power supply (middle-connected)

Example using thick cable
This example is used to check loading on both sides of a middle-connected
supply on a thick cable trunk line. Keep the loads, especially the higher ones,
close to the power supply. If the device location is fixed, put the power supply
in the center of the highest current concentration.
section 1
244 m
(800 ft)
TR T T
D3 D2
0.25A 0.25A
TR = terminating resistor T = T-Port tap
PT = Power Tap D = device
According to the look-up method, section 1 is operational while section 2 is
overloaded.
Value of
Total maximum current
Total current required
1. Find the voltages for each device in section 1 using the equation for
thick cable.
SUM {[(L
D1
A.[(100 x (0.0045)) + (1 x (0.005))] x 0.25 = 0.12V
0.25A
D2
B.[(400 x (0.0045)) + (2 x (0.005))] x 0.25 = 0.45V
0.25A
D3 C.[(800 x (0.0045)) + (3 x (0.005))] x 0.25 = 0.90V
0.25A
2. Add each device's voltage together to find the total voltage for section 1.
0.12V + 0.45V + 0.90V = 1.47V
power
supply
122 m
(400 ft)
60 m
30 m
(200 ft)
(100 ft)
T PT
D1
0.25A
Section 1
1.25A (approximately)
0.75A
x (0.0045)) + (N x (0.005))] x I
n t
Determine Power Requirements
section 2
244 m
(800 ft)
122 m
(400 ft)
T T
D4 D5
0.25A 1.5A
Section 2
1.25A (approximately)
2.25A
} < 4.65V.
n
Publication DNET-UM072C-EN-P - July 2004
4-23
T TR
D6
0.5A
31515-M