GB1364650A - Structure of coils for use in transformer - Google Patents

Abstract

1364650 Transformers MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 14 Dec 1971 [17 Dec 1970 (12)] 58103/71 Heading HIT A transformer comprises a primary and a secondary coil winding, 100 and 200 (Fig. 3) respectively, each separately impregnated with resin, 7, e.g. polyester or epoxy resin, and individually subjected to thermosetting, and at least one conductive member, 16, which does not form part of any closed circuit and which is connected to one of the coils or to ground. The resins used for impregnation of the two coils may be of different types. The windings are each made in two sections so that the coil unit is still operative if one of the sections should develop a fault. The conductive member is preferably made of a flexible material, e.g. metal wire, vapour deposited aluminium film or metal foil. In one embodiment of the invention a conductive member, connected to earth, is fixed near the H.T. coil, the coils being arranged such that the conductive member is intermediate them. The space between the H.T. coil and the conductive member is determined either by suitably arranging both in the mould when impregnation takes place or by inserting between them insulating material, e.g. unwoven polyester cloth. In another embodiment of the invention, shown in Fig. 8, a coil bobbin 20 is used for mounting the H.T. winding on the iron core of the coil unit. Two conductive members, 16 and 16<SP>1</SP>, are disposed within this bobbin, one being connected to ground or to the L.T. winding and the other to the H.T. winding. Several other embodiments of the invention are described in which one or two conductive (screening) members are used and may be connected together or to the coils and are located in the resin casings of one or both coils or in a separate resin casing intermediate the coils.