A performant antigalloping device for the 400 kV O/H lines with 3 subconductors was designed tested manufactured and installed in Romania in 2015. Live-line procedures available

Following the implementation of the antigalloping devices for the 400 kV o/h lines with 2 subconductors per phase, as explained in our paper presented by the occasion of the ICOLIM 2014 in Budapest, a new antigalloping device of the same torsional damper and detuner pendulum type was created and already implemented on some of the 400 kV with 3 subconductors per phase in Romania, in 2015. The device is characterized by combining the properties of torsional damping with those of detuning, avoiding the energy transfer from the torsion to the vertical motion. The torsional damping leads to a higher critical wind speed at which the galloping instability appears and limits its amplitude, while the detuning characteristic of the device separates the torsional and vertical frequencies. The new device design took the main shape of that used for 2 conductors per phase, the rigid spacers being now triangular and some differences in the dimensions having to be considered. Nine alternatives were taken into account for testing. Finally, based on the transfer function diagrams, two alternatives were further developed and manufactured, the Light (L) and the Heavy(H). The axonometric drawing and the view one are shown in the figure. The difference between these two consists of different counterweights (H-10.9 Kg and L-8.9 Kg) and different distance between the counterweight axis (H-860 mm, respective L-830 mm). The concept of the damping pendulum as torsional damper and detuner (TDD) was created and reported in 1993 by its authors led by Prof. Jean-Louis Lilien from University of Liege-Belgium. Several versions were designed, tested and even used in some minor projects, demonstrating their high capacity to solve the risk of the overhead line conductor galloping with usual frequencies in the range 0.4-0.6 Hz. The parameter describing the damping performance is the transfer function with values in the range 1.5-2.5 in the case of the previous versions. The new version transfer functions came to much better values. A description of the pendulum parts, tests carried out and the final design are presented. The pendulum can be easy mounted in live-line conditions.