Medium Voltage technical guide - Schneider Electric

Design rules Busbar calculation
AMTED300014EN.indd
Mechanical busbar strength
By making the assumption that the ends of the bars are
sealed, they are subjected to a bending moment whose
resultant stress is:
With:
η
η = F1 • l
12
•
v
Is the resultant stress in daN/cm 2
Distance between insulators
l
for same phase
I/v Is the modulus of inertia between
a bar or a set of bars
(value chosen in the table below)
η =
482.3 • 70
12
η = 195 daN/cm 2
•
I
1
14.45
70 cm
14.45
The calculated resultant stress (η = 195 daN/cm 2 )
is less than the permissible stress for the copper busbars
1/4 hard (1200 daN/cm2):
The solution is OK
Arrangement Busbar dimensions
100 x 10 (mm)
S cm 2 10
m Cu daN/cm 0.089
A5/L daN/cm 0.027
x
x'
x
x'
x
x'
x
x'
x
x'
x
x'
I cm 4 0.83
I/v cm 3 1.66
I cm 4 83.33
I/v cm 3 16.66
I cm 4 21.66
I/v cm 3 14.45
I cm 4 166.66
I/v cm 3 33.33
I cm 4 82.5
I/v cm 3 33
I cm 4 250
I/v cm 3 50
cm 3
39