GB660965A - Improvements in and relating to electric transformer cores - Google Patents

Abstract

660,965. Transformers. BRITISH THOMSON-HOUSTON CO., Ltd. Sept. 12, 1949 [Sept. 24, 1948], No. 23522/49. Class 38 (ii). A laminated core for electric transformers having at least one closed magnetic circuit of substantially rectangular configuration including two straight legs interconnected by yoke portions so that a core opening is encircled by the legs and yokes wherein each yoke portion has two branch members, one at one side and the other at the other side of the median plane of the core defined by the axes of the legs and wherein each branch member includes a plurality of laminations whose median lines are curved and lie in planes at right angles to the median plane of the core so that the ends of these laminations join the laminations of the legs whose planes are at right angles to the median plane of the core. Leg portions 2, 3 are built up of straight laminations into a cruciform pattern as shown at 4, the inner layers 6, 9 ... 14 being interconnected by means of yoke caps 7, 11 ... 13 so as to form closed loops while the outer layers 15, 18 ... 20 are connected by means of U-shaped parts 16, 21 ... 23 lying in a plane at right angles to the plane through the leg portions. The joints between the leg portions and the yoke caps and between the leg portions and the U-shaped parts may be of any well-known type. A core construction according to the invention occupies less space than the conventional type of core since the " yoke height " is only half that which obtains in the latter type of core; also there is a saving of material in the leg portions due to the fact that the packets of laminations in the leg portions are progressively shorter towards the outside of the leg. Another embodiment is described in which the internal layer of the leg portions and the interconnecting yoke caps are replaced by the conventional flat stacked lamination construction and in yet another modification the yoke caps are replaced by a further series of U-shaped members. The construction may equally well be applied to cores having a single winding leg and a socalled divided yoke.