The mechanical effects of short-circuit currents in - Montefiore

a) b)
4
+25 %
0 %
3
2
F t,c / F st
1
0
-25%
0 1 2 3 4
F t,m/F st
123
6
5
4
3
F pi,c/ F st
Figure 8.14: Cases *12 to *14
a) Case *12: Short-circuit tensile force F t (18 tests)
b) Cases *13 and *14: Pinch force F pi (19 tests)
8
6
4
F c / F st
2
0
+25 %
0 %
-25%
34 m 68 m 102 m
0 2 4 6 8
F m / F st
Figure 8.15: Cases *9 to *11: Short-circuit force Maximum of F t and
F f
Span lengths: 34 m (4 tests), 68 m (4
tests), 102 m (8 tests)
2
1
0
+25 %
0 %
-25%
0 1 2 3 4 5 6
F pi,m / F st
Cases *4 to *7 (Laborelec 1980)
There are droppers in the distance of 2,5 m and 5 m
from the ends of the span, but through 88 % of the bus
conductor the short-circuit current flows. The conductor
in the west cable is able to swing out free, but the
movement of the cable in the east is hindered by the
droppers to ascend as high as the west cable.
Nevertheless, these droppers are ignored.
In Cases *4 and *6, the conductor is Cu 324 mm 2 , in
Cases *5 and *7, it is Cu 105 mm 2 .
In Figure 8.16a and Figure 8.17a, the forces are
separately shown for west and east. In Figure 8.17a, the
standard calculates higher drop forces because in the
tests, the conductors have a considerable kinetic energy
at the beginning of the fall.
In three tests, droppers are in midspan. Therefore the
calculation is done according to paragraph 3.3. The
results are shown in Figure 8.16a and Figure 8.17a.
The horizontal displacements are given in Figure 8.16b
and Figure 8.17b without and with droppers in midspan.