GB920289A - Improvements in or relating to section insulators for use in overhead conductors of electric traction systems - Google Patents

Abstract

920,289. Section insulators. BRITISH INSULATED CALLENDER'S CABLES Ltd. Sept. 25, 1961 [Sept. 26, 1960], No. 33070/60. Addition to 904,944. Class 36. A section insulator for overhead electric traction systems comprises a single pair of outer runners 2, held in spaced horizontal relationship by transverse members 12 and constructed from metal end parts 3 and tension insulators 5 in such a way that the metal end parts 3 do not over-lap, and two inner runners 10 which are formed either from the contact wires 1 or an extension thereof and which diverge from each other over all or part of their length and overlap adjacent their free ends, the outer runners 2 being connected, at their free ends, to the contact wires 1 by a fitting or fittings 6, 7. The tension insulators 5 are preferably made from glass fibre rods or tubes with a covering of an insulating material resistant to abrasion and tracking such as P.T.F.E., P.T.F.C.E., or butyl rubber. This resistant layer may be formed from collars of normal or high alumina ceramic toughened glass or silicon nitride separated by washers of the above materials so shaped as to fit into dish-shaped indentations in the collars. A layer of cold-curing silicone rubber or like resilient insulating material may be provided on the rods or tubes before the collars and washers are threaded thereon. The inner runners are preferably adjustably mounted at the end of a member 13 mounted on one of the transverse members 12 and are preferably bent out and upwards from the centre line at their ends to form arcing horns 11. The metal endparts of the outer runners preferably rise slightly at their ends and are preferably of inverted T cross-section with convex running surfaces.