Simulations of the controlling effect of interphase spacers on conductor galloping

Conductor galloping on overhead transmission lines can be a major problem and the interphase spacers is a countermeasure which has been found to be effective. There is, however, little theoretical basis for their use and for defining their design parameters. In this paper, a galloping simulation model is used in which the aerodynamic force is replaced by a sinusoidal excitation with a frequency equal to the natural vertical galloping frequency of the line. This is used to analyze the ability of interphase spacers to control the galloping amplitude. A full-scale free oscillation test on a triple-span transmission line was conducted and good agreement was obtained with the simulation calculation. Then by simulation, the changes of galloping amplitude and conductor tension were determined in terms of the initial excitation amplitude, both with and without interphase spacers. The dynamic spacer tension during galloping was also computed. The results clearly indicated the effectiveness of interphase spacers to control galloping, and show that the methods used will be useful and applicable to the design of interphase spacers to control galloping and to determine where they can best be deployed.