The mechanical effects of short-circuit currents in - Montefiore

small sub-conductor separation as/ds, the pinch is
generally very limited and its duration is also
very short. The oscillograms in Figure 3.5 to
Figure 3.8 show clearly the electromagnetic
force (the 50 Hz can be seen, progressively
transferred to 100 Hz) with a sudden peak, just at
the instance of contact. In the case of very large
subspan and very short sub-conductor separation,
the pinch is noticeable smaller, Figure 3.5. It is
quite obvious that the situation is similar to
Figure 3.3, single strain conductor.
Figure 3.5 Tensile force with bundle pinch in a strain
conductor; similar to case *8, twin bundle;
very large subspan length, short sub-conductor
separation: ls/as = 400; as/ds = 1,9, λ = 211
Figure 3.6 Tensile force with bundle pinch in a slack
conductor; case 3, Figure 1a; twin bundle;
large subspan length, short sub-conductor
separation: ls/as = 79; as/ds = 1,9; λ = 40
Figure 3.7 Tensile force with bundle pinch in a strain
conductor; case *15, Figure 15.2; twin bundle;
large subspan length, short sub-conductor
separation: ls/as = 93; as/ds = 2,1; λ = 44
Figure 3.8 Tensile force with bundle pinch in a strain
conductor; similar to case *8, twin bundle;
large subspan length, short sub-conductor
separation: ls/as = 50; as/ds = 1,9; λ = 26
In the opposite case, a large sub-conductor
separation as/ds, which is so called wide
bundling, the contact do not necessary appear
and the increase of tension can be rather high and
its application rather low. We cannot see any
more the electromagnetic force details in Figure
3.9 to Figure 3.11. The electromagnetic force is
completely masked by the increase of tension in
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the conductor which is due to its movement trying to
come into contact. This case is the most dangerous
case.
Figure 3.9 Bundle pinch in a strain conductor; triple bundle;
case *13, p. 67, Figure 13.3: displacement of the
support and pinch effect in the bus;
large subspan length, large sub-conductor
separation: ls/as = 67; as/ds = 12,4; λ = 4,7
Figure 3.10 Bundle pinch in a strain conductor; case 8 §10.9 of
the volume 2, twin bundle;
short subspan length, large sub-conductor
separation: ls/as = 21; as/ds = 16,5; λ = 1,3
Figure 3.11 Bundle pinch in a strained conductor; case 8 §10.7
of the volume 2, twin bundle;
large subspan length, large sub-conductor
separation: ls/as = 131; as/ds = 16,5; λ = 7,9
The upper oscillogram shows the spacer
compression and the lower one the tensile force in
the sub-conductor.