GB1322973A - High-voltage insulators - Google Patents

Abstract

1322973 Electrical insulator ASSOCIATED ELECTRICAL INDUSTRIES Ltd 5 July 1971 [8 July 1971] 33249/70 Heading H2C A voltage grading capacitance or a high voltage insulator comprises capacitance plates formed by metal ports 26, 34 or 18, 20 and a dielectric layer 28, Fig. 2, 16, Fig. 1, provided along at least part of an insulating support column, Fig. 2, or an insulating enclosure of an interrupting break of an electric circuit interrupter, Fig. 1, and the capacitance is electrically connected in parallel with the support column of the interrupting break. The permittivity of the dielectric layer is > 1000. The connection of dielectric layer 28 to the metal parts may be by means of flexible connections 30, 32, Fig. 2, connecting the metal plates 26, 34 separating insulator sections 22. Alternatively the layer 16 may be extended to make electrical contact with the flanged end members 18 and 20, Fig. 1. The dielectric layer need not extend the full length of an insulator, it being connected to the terminal plates by metallization and it may have varying thickness to improve the field distribution. Barium titanate, a ceramic insulator may comprise the layer used and may be deposited by plasma spraying in thicknesses, for example, ranging from 2À5-25 mm. Electrical connection to the layer may be made by first applying a metallic layer, e.g. nickel, nickel chromium alloy by flame or plasma spraying, to which metal-to-metal connection is made by clamping, soldering &c. Electroless deposition (nickel) and air-drying pastes (silver) may be used to form the metallic layer. The insulator material of Fig. 2, may be of porcelain and the flanges 24 are cemented thereto. The interrupter of Fig. 1 is described in Specification 1,282,570.