GB1209690A - Improvements in or relating to electrical insulators - Google Patents

Abstract

1,209,690. Insulators. CENTRAL ELECTRICITY GENERATING BOARD. 22 Aug., 1969 [19 Aug., 1968], No. 39547/68. Heading H2C. An electric insulator comprises a plurality of rigid plastics sheds 11-14 closely spaced so that the re-entrant shapes between the sheds have a ratio of depth to width of at least 5 to 1, preferably 10 to 1. Adjacent sheds are of different sizes to avoid arcing. The sheds which may be conical, as shown, or in the form of a frustum of a cone with a flat top or a double cone with two portions of differing apex angles and which may have a cone semi-angle between 10 and 90 degrees are secured by adhesive to a rod or tube body member 10 of porcelain or resinbonded fibre-glass. The cones may be flared outwardly at the bottom end. The sheds may be formed with grooves on their inner end surfaces containing adhesive for sealing to the body member 10. The sheds may also have webs or regions of increased thickness at their inner ends so as to fit against one another along member 10. (Figs. 3, 4, not shown). Insulating spacers or elastomeric O-rings may be provided between the sheds (Figs. 5-8, not shown). Fig. 9 (not shown) indicates a disc type insulator having concentric cylindrical sheds of plastics having different depths. Alternatively a plastics spiral may be secured on one face of a disc and the extent by which the sheds extend downwardly from the disc varies along the length of the spiral so that the outer peripheries of the sheds are well separated and may be formed with incisions. The sheds may be directly secured to a porcelain disc or through an intermediate plastics disc. An outer skirt, preferably cylindrical, may be provided around the disc outside the sheds.