GB1229437A - - Google Patents

Abstract

1,229,437. Transformers; inductors. BROWN, BOVERI & CO. Ltd. 24 July, 1968 [10 June, 1968], No. 35380/68. Heading H1T. A core for a three-phase choke or transformer comprises two yokes 13, 14 spaced apart by three columns 10, 11, 12 whose axes are disposed at respective comers of a triangle, each column comprising several coaxial, spaced-apart, cylindrical sections 15, the laminations 41 (Fig. 4b) of which are arranged in radially-disposed packets. The yokes may be annular or of a generally triangular shape and may be wound from a continuous strip. The laminations of the yokes and of the column sections may be glued together with a self-hardening polyester or an epoxy resin. Bandages may also be glued around the column sections. An insulating layer of a synthetic fibrous material, e.g. transformer board, may be glued to the end faces of the column sections. The spacers 16 between the sections are preferably cylindrical, ring-shaped or ring- segment shaped blocks of a ceramic material or of a loaded casting resin. Each column section may be provided with an axial hole 42, which may contain a welded tube, corresponding holes being formed in the yokes either by spacing apart a pair of adjacent laminations or by drilling the yoke after it has been wound. Bolts extend through the holes in the yokes, being fastened on the outer side to clamping plates. Bracing bolts or ropes 74, Fig. 7 (not shown), extend along each column within the hole 42 and are fastened at their ends to the bolts passing through the yokes. The bracing bolts or ropes are made of a non-magnetic insulating material, e.g. a polyester resin strengthened with fibres. In an alternative bracing arrangement the columns are clamped between H-beams adjacent each yoke by tiebolts which pass externally of both the columns and the windings disposed thereon. In either arrangement the tension in the bracing members is maintained by stacks (77) of spring plates having non-linear elastic characteristics.