South African Cross Rope Towers Aim to Optimize Cost & Performance
During the late 1970s, as South Africa began to introduce lines at 765 kV, new families of guyed-Vee structures were studied to achieve cost savings versus traditional self-supporting pylons. The heavy lattice cross-arms from which phase conductors were suspended on these new structures were then further optimized by adoption of metallic rope and later cross-rope designs. For example, a compact cross-rope design employing a delta configuration was introduced in the late 1990s for lines of 200 km or longer. Although not cheaper on a per pylon basis, operational cost savings could be realized due to the design’ s favorable capacitance and inductance characteristics.
Photos: INMR ©
Recently, a new generation of cross-rope structure being tested aims to realize added savings for 765 kV suspension towers in terms of tower weight per conductor attachment point. At a height of 31.5 m, for example, this new structure is some 5000 kg lighter than earlier versions with further reduction in project costs due to the impact on guys and foundations. Clearances marked on cross-rope structure of 400 kV line to Namibia.
Photo courtesy of Eskom
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