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When a conductor is iced, it presents an unsymmetrical corss-section with the windward side having less ice accumulation than the leeward side of the conductor. When the wind blows across such a surface, there is an aerodynamic lift as well as a drag force due to the direct pressure of the wind. the two forces give rise to torsional modes of oscillation and they combine to oscillate the conductor with very large amplitudes sufficient to cause contact of two adjacent phases, which may be 10 to 15 metres apart in the rest position.

Let the final temperature = t°C. 95}. 28t) 108. A trial and error solution yields t ≈ 44°C. ). Example. 5 In the previous example, calculate the final temperature (or temperature rise) if the solar irradiation adds (a) 10 watts/m, and (b) 1160 W/m2 giving a contribution of 37 watts/m to the conductor. Solution. 1°C. We observe that had the ambient temperature been 50°C, the temperature rise would reach nearly the maximum. This is left as an exercise at the end of the chapter. v. transmission lines.

5. 3, work out dc alternative for India to evacuate these powers to load centres. 6. Write brief descriptions of (a) aeolian vibration, and (b) wake-induced oscillations. Describe the measures taken to minimize the damage due to them. v. transmission lines are always stranded. Most common conductors use a steel core for reinforcement of the strength of aluminium, but recently high tensile strength aluminium is being increasingly used, replacing the steel. The former is known as ACSR (Aluminium Conductor Steel Reinforced) and the latter ACAR (Aluminium Conductor Alloy Reinforced).