GB907827A - Improvements in or relating to magnetic core structures for use in electrical inductive apparatus - Google Patents

Abstract

907,827. Transformers. WESTINGHOUSE ELECTRIC CORPORATION. Oct. 12, 1959 [Oct. 15, 1958], No. 34458/59. Class 38 (2). A magnetic core formed of grain oriented strip laminations has the lamination layers stacked in groups of three or more with their edges overlapping the edges of adjacent laminations so that the joints are staggered. Figs. 1 and 2 show a core formed with yoke strips 58, 78 arranged in stepped groups. The strips are located in their correct positions when positioning holes 72, 74, 76 or notches 82, 84, 86 in the leg laminations are in alignment and the yoke laminations are in place. The projecting edges of the groups of yoke laminations shown in Fig. 2 assist cooling but instead of the repeating arrangement shown the slope of the joints in alternate groups of lamination layers may be in opposite directions. In an alternative arrangement, the laminations may be square ended and have two preferred directions of orientation (Fig. 4, not shown). In other arrangements overlapping of the joints is achieved by shaping the strips as shown in Figs. 8 or 10. The partly squared ends of the strips shown in Figs. 8 and 10 enable pressure to be applied to them, mechanically or manually, during assembly. Fig. 14 shows the arrangement of a three-phase shell type core in which the joints between the limbs 304, 306, 324, 326 and the intermediate yoke members 312, 314, 332, 334 are stepped by shaping the V-ends of the latter as shown in Fig. 20. The groups of laminations may have their joints in repeating order or the second group may be reversed to form a continuous stepped arrangement as shown in Fig. 21. The yokes may be wider than the limbs and the overlap between joints in adjacent layers is normally at least six times the lamination thickness. There may be slight air gaps at the joints but the arrangements described are said to reduce both the effective air gaps at the joints and the noise level. The core may be clamped in a frame after assembly. Specification 554,000 is referred to.