The first spacer damper designed in Italy, and one of the first in the world, is the RIGANTI spacer damper. It was developed more than 35 years ago, and, since then, widely used in Italy and abroad. Its exclusive and ingenious articulation, world patented, allow the rubber components to work in full compression, developing the maximum damping effect with practically limitless fatigue endurance.
After NES took over the RIGANTI Fitting Department, the spacer damper design has been continuously updated taking advantage of the new technologies and materials. The shape and the weight have been improved to meet to the increasingly stringent requirements of the transmission line. However, the core of the design: the damping articulation, still remains unchanged in its principles.
To date, NES can offer a modern spacer dampers, well proven on the field, capable to control, within the safety limits recommended by IEEE and CIGRE, the aeolian vibration and the subspan oscillation of the conductor bundles, while maintaining their elastic and damping characteristics practically constant for the whole life of the line. Moreover, NES Design Department disposes of computer programs able to anticipate the vibration behaviour of any transmission line conductor bundle and to define the quantity and optimum positioning of the spacer damper units.
The distribution scheme of the NES spacers dampers considers a staggered positioning optimized for the control of the subspan oscillation. Moreover, the end subspans are kept short enough to increase the torsional stability of the bundle, which strongly contribute to the restoration of the bundle rest position in case of short circuit, galloping and ice drop.
NES provides the Clients with a clear and complete description of the installation procedure and the in-span location of the spacers dampers for any span length.
NES spacer dampers are fully in accordance with IEC 61854 Standards and with the main Utilities’ Specifications. Besides, they are specifically designed to make the installation on the line easy and univocal considering the difficult working conditions of the linemen along the overhead conductors.
The spacer damper clamps can be of four different types:
- Nut cracker bolted clamp
- Cantilever bolted clamp
- Cantilever rubber lined clamp
- Open clamp with armour rods
The central frame is dimensioned and shaped to provide a suitable inertial effect and to protect the articulations during short circuits.
The NES spacer dampers are designed to withstand tension and compression forces developed by short circuit currents up to 50 kA.
The NES spacer dampers are free of defects and irregularities; they have all outside surfaces smooth and all edges and corners well rounded to allow safe handling and minimise Corona emission and radio interference (RIV).
NES spacer damper components are made of materials conforming to the requirements of IEC 61284 and having an excellent corrosion resistance that is maintained for the whole expected conductor lifetime, without the need of maintenance. Elastomers, used in the articulations as damping elements, have been formulated to provide good resistance to ageing, to be electrically conductive and to have adequate resistance to the effect of ozone, ultraviolet radiation, air pollution and conductor heating, over the entire range of service temperature.