Artikel,
Phase-to-phase Spacers for EHV Bundle Conductor Transmission Lines
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Zusammenfassung
Recent trends in EHV transmission line construction are
toward the use of large-diameter bundle conductors to meet
the increasing power demand. But these conductors are
likely to be subject to low-frequency high-amplitude oscillation,
i. e., galloping, due to increased torsional rigidity.
Also because of the increasing difficulty in securing the
right-of-ways, it has often become necessary to build such
lines even in areas geographically and meteorologically unfavorable
for conductor oscillation performance.
The conductor galloping may cause such electrical faults
as phase-to-phase or phase-to-ground flashovers and mechanical
failures as conductor fatigue and damages of conductor
fittings and insulator assemblies. It has been confirmed
that phase-to-phase spacers are effective for preventing
the conductor galloping, but in Japan so far, practical
use of such spacers is limited to single conductor lines of 77
kV and below. This paper presents the results of a fullscale
test conducted under natural wind condition using a
plastic air-foil as simulated icing on conductor for the
purpose of applying the spacers to EHV bundle conductor
lines, and also introduces the mechanical design criteria of
the spacers for control of galloping. The following outlines
the contents of the paper:
1) The amplitude of conductor movement and conductor
tension during galloping are reduced by about 50 % by
installing a set of spacers at a point of the span.
2) The galloping inception wind velocity is raised by about
3 times by adopting the spacers.
3) It is desirable to restrain the torsional oscillation of the
conductors which is a cause of developing galloping, by
making t..1-ie end connection of the spacers rigid against
the conductor rotation.
4) Not only static but also dynamic strength are required
because of the inertia of the spacers during galloping.
