A Finite Element Analysis of Detuning Pendulums
for the Control of Galloping
(-)Abstract
The higher incidence of galloping in bundle conductors as compared with
single conductors is discussed together with the merits of some torsional control
approaches which increase the bundle's torsional/vertical frequency ratios. The
outline of a finite element analysis of a twin bundle is presented and is shown to
give good results for the vertical and torsional frequencies. Pendulum detuners
and the effects of ice and wind-, using the Ontario-Hydro expressions, are
incorporated. The first three torsional and vertical modes of one span in a
five span section are presented for a range of ice thicknesses. The results
support the effectiveness of pendulum detuners in increasing the frequency
ratios. There is a broad agreement with the Ontario-Hydro theory but certain
differences are apparent, particularly with regard to the rate and order of
modal convergence. The conclusions concerning the importance of these
differences are necessarily tentative and require the examination of further
span configurations.before firm conclusions can be formed.
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