The mechanical effects of short-circuit currents in - Montefiore

Figure 3.61 Displacement of the span at
a) t = 0.1 s; b) t = 0.4 s
Figure 3.62 Displacement of the span at
c) t = 0.62 s; d) t = 0.93 s
X
TIME 0.15
a.)
X
Z
Z
Y
Y
TIME 0.40
TIME 0.62
c.)
b.)
Z
X Y
X
TIME 0.93
Whereas, due to the halving of the conductor length, the
horizontal motion now has twice the frequency ( Figure
d.)
Z
Y
64
3.63b), the period for the unrestrained vertical direction
(Figure 3.63c) remains approximately the same as for
the calculations without interphase-spacers. From
(Figure 3.63d) it can be seen that the horizontally
unmoving mid-point of the conductor moves vertically
in sympathy at the same frequency. For the tensile force
on the conductor in (Figure 3.63a) this means that, due
to the fitting of the interphase-spacers, although twice as
many tensile maxima F t occur, the number of drop
maxima F f and their times remain the same. Overall, it
can be seen that the value of amplitude F t ≈ F f ≈ 22
kN governing the design of the points of suspension has
remained largely unchanged. This means that, although
fitting a interphase-spacer does not cause higher shortcircuit
tensile forces, it does not cause substantially
lower forces either.
a.)
b.)
c.)
d.)
Seilzug
-kraft
in kN
.5
Seilaus
-
lenkung
in m
.0
-.5
.0
Seil-
-.2
durchhang
in
m
-.4
-.6
Seildurchhang
in .0
m
-.5
-1.0
30.
20.
10.
0.
.0 .5 1.0 1.5
Zeit in s
2.0 2.5 3.0
.5
1.Auschwingmaximu
1.Fallmaximum
.0 .5 1.0 1.5
Zeit in s
2.0 2.5 3.0
.0 .5 1.0 1.5
Zeit in s
2.0 2.5 3.0
.0 .5 1.0 1.5
Zeit in s
2.0 2.5 3.0
Figure 3.63 Time characteristics of the span
with interphase-spacers
a) conductor tensile force
b) horizontal motion at l/4
c) vertical motion at l/4
d) vertical motion at l/2
Figure 3.64 shows the tensile/compressive stresses
caused by the horizontal motion of the conductors in the
phase spacer.