GB639040A - Improvements in electric conductors for high voltage overhead lines - Google Patents

Abstract

639,040. Electric cables. BRITISH INSULATED CALLENDER'S CABLES, Ltd., BRAZIER, L. G., and HARTSHORN, P. R. Aug. 11, 1948, No. 21158. [Class 36] An overhead power conductor 2 is surrounded by a conduc- , tive structure 1 of openwork or discontinuous form which is in electrical connection with the conductor, the outer edges of the structure, which are of small radius of curvature, defining an envelope that encloses and screens the conductor. The screen may be in the form of an open wire helix, Fig. 1, which may either hang directly on the conductor or be supported, as by conducting spokes, so as to be coaxial with the conductor. The pitch of the helix may be reversed at frequent intervals so that the screen may be sprung into position over the conductor. Alternatively, the helix may be made from a flat metal strip 5 or an L-shaped metal strip 6 applied edgewise, Fig. 3. The radius of curvature of the peripheral edge of the strip corresponds to that of the wire 1, Fig. 1. In a further modification, the screen may comprise a number of thin discs fitted on the conductor at frequent intervals and having rounded peripheral edges which may be continuous or broken up into small domes. Another type of screen comprises a cage of split wire rings connected together by a longitudinal spacing strip. A modified form may be made by bending a single length of wire 11 as shown in Fig. 6. In a further embodiment the screen consists of a series of open wire helices each consisting of a few turns of wire and having a varying diameter so that the ends of each section grip the conductor. In all the above examples the screens may be wholly of metal or may be formed of a non-conductive material such as thermoplastic, parts of which are metallised.