Mechanical Design and Test of 1200 KV Semi-Flexible SF6 Insulated Transmission Line

An SF6 insulated Semi-Flexible transmission line is described which uses a corrugated aluminum enclosure to reduce cost and provide flexibility. Mechanical behavior was evaluated using finite element computer analysis, bending, hydrostatic, thermal, vacuum and fatigue tests. A 711 mm (28 in) internal diameter, 4 mm (0.16 in) wall, 3004 aluminum enclosure with 19 mm (0.75 in) deep corrugations at a pitch of 70 mm (2.75 in) was shown adequate for internal and external pressure. A field installation centerline bending radius of 15 m (50 ft) was demonstrated. Electrical and mechanical parameters of the 1200 kV and a 550 kV design are reported. These meet the performance and cost objectives of a development program for semi-flexible SF6 insulated transmission lines jointly funded by the U. S. Department of Energy and Westinghouse.