GB1004493A - Method of manufacturing insulated electrical conductors and conductors manufactured according to the method - Google Patents

Abstract

1,004,493. Insulated electric conductors. ALLMANNA SVENSKA ELEKTRISKA A.B. July 4, 1962 [July 5, 1961], No. 25589/62. Heading H1A. To insulate a bundle of conductors 10, consisting of several separate conductors 11 insulated from each other by glass yarn 12, the bundle is wound alternately with layers of insulating material 13 and thermoplastic material 14 and heated under pressure to a temperature sufficient to slightly melt the thermoplastic material so that in subsequent working it adheres to adjacent layers of insulating material and forms a rigid casing around the conductors, and is then impregnated with a liquid thermosetting resin, e.g. an unsaturated polyester resin or epoxy resin. So that the bond between the layers may not loosen during impregnation the thermoplastic material must be insoluble or nearly so in the liquid impregnating resin. The resin in the impregnated insulation can then be cured without placing the insulated conductor in a mould, since the thermoplastic material is usually completely solid at the temperature required for curing. The insulating material is usually mica tape or mica sheet, the mica being attached to a material such as paper or glass fabric with a resinous binder. Other insulating materials may be used such as paper glass tape, glass fabric and tape or fabrics of other fibrous materials such as asbestos, cotton and silk. A number of materials suitable for the thermoplastic material in the form of thin thermoplastic foils can be used (see Specification), the one chosen in each case depends to a great extent on the impregnating resin to be used. A number of impregnating resins may be used (see Specification), and during vacuum pressure treatment the impregnating resin penetrates through the openings 16 left in the outer sealing tape 15 and fills up the pores and spaces in the insulation. The openings 16 are then sealed with sealing tape 15 and the winding is left in a furnace to cure the impregnating resin. The thermoplastic material need not be applied between each layer of insulating material but may be applied only between the outer layers of insulating material. It can also be applied with an interspace, or even in the form of thin loaves of suitable size. Further, the thermoplastic material may be arranged as a component of the insulating material, for example, it may be woven into the product in the form of fibre threads, or it may be arranged on one surface of the insulating material. U.S.A. Specifications 2,324,483 and 2,656,290 are referred to.