Eaton Electrical MN05001002E - page 24

Intelligent Technologies QCPort System Install Manual
November 2005
MN05001002E For more information visit
www.eatonelectrical.com Page 24
Example 3 Middle Connected Power Supply
2. Sum up the currents per section
Section 1 (QCPort Interconnect) = 0.2 + 0.3 + 0.1 = 0.6 A (OK)
Section 2 (Backplane) = 1.0 + 2.0 = 3.0 A (OK)
Find the voltages for each device using the equation for Long Run.
SUM {[(L
n
x (0.105)) + (N
t
x (0.005))] x I
n
} <= 4.65V
Device 1 [(9 x (0.105)) + (3 x (0.005))] x 0.2 = 0.19V
Device 2 [(6 x (0.105))+ (2 x (0.005))] x 0.3 = 0.19V
Device 3 [(3 x (0.105)) + (1 x (0.005))] x 0.1 = 0.03V
Device 4 [(0 x (0.105)) + (1 x (0.005))] x 1.0 = 0.00V
Device 5 [(0 x (0.105)) + (2 x (0.005))] x 2.0 = 0.02V
Add each Devices voltage together to find the total voltage per section.
Section 1 – 0.19+0.19+0.03 = 0.41V (OK)
Section 2 – 0.00+0.02 = 0.02V (OK)
Results
Since the total voltage does not exceed 4.65V in either section, the system will operate
properly.
T D3
.1A PS D4 1 A
D2
.3 A D5 2 A
3 foot 3 foot 3 foot 0 foot
T
D1
.2 A
0 foot
Section 1 Section 2
3 foot