GB1220577A - Improvements in transformers having laminated magnetic cores - Google Patents

Abstract

1,220,577. Transformers. ENGLISH ELECTRIC CO. Ltd. 1 March, 1968 [6 March, 1967], No. 10369/67. Heading H1T. A transformer core leg comprises a number of packets of laminations of different widths, as in Fig. 6, the laminations in at least the outer two packets 50, 51 on each side of the leg having a plurality of laterally-spaced slots extending between the junctions of the leg with top and bottom yokes so as to reduce the eddy currents induced near these junctions by leakage flux. The laminations may be slotted as in Fig. 4, the unslotted end portion being interleaved with the laminations of one of the yokes. The slots near the sides of the laminations may, however, be more closely spaced than those near the centre. The laminations in each packet may be similar, so that the slots are in alignment, or they may be slotted in different ways to provide greater subdivision of the leg. The ends of the laminations may be mitred. Some of the slots may be filled with a solid non-magnetic electrically insulating material and the unfilled slots used for the circulation of the cooling fluid. The laminations preferably have an additional or more effective electrically insulating coating over their slotted portions to prevent slots being electrically bridged by the adjacent laminations. The core legs may be clamped between a number of non-magnetic electrically insulating plates 16 or the laminations may be held together by banding or bonding. The core is insulated from the windings by a barrier 53.