GB253189A - Improvements in or relating to insulating bushings for electrical apparatus - Google Patents

Abstract

253,189. Reyrolle & Co., Ltd., A., and Allan, A. March 10, 1925. Transformers.-In an insulating bushing for high voltage apparatus comprising outer insulators A, A<1>, Fig. 1, each of one or more sections, connected together by a supporting casing or member B, and to permit relative movement between the central conductor C and insulators due to unequal expansion, the conductor C is rigidly attached at one end C<1> to one of the insulators A<1>, whilst the other end makes a plug and socket or other sliding connection with a socket or member G, Fig. 2, fixed to the other insulator A. The conductor C is immediately surrounded by a condenser insulator D of paper or like material on a metal core D<1> which is connected to the conductor C by a flexible lead. The condenser insulator is supported by the casing B by means of a flange D<2> clamped to an intermediate part of the condenser insulator, the ends of which are thus left free. The casing B also contains a protective transformer arranged around the condenser insulator D, the secondary windings being connected to terminals mounted in an outer box E on the casing B. The bushing may be filled with oil. The socket G may have a safety valve G<1> to relieve excessive pressures; and a casing F with inspection windows F<1> and an arcing ring F<2> is fitted on the upper insulation section A. In a modified construction more especially for use with oil immersed apparatus the central conductor is hollow, the upper socket has slots to allow oil to flow into and out of the bushing through the conductor and at the lower immersed end of the conductor a ball valve is fitted to prevent any sudden or rapid rush of oil.