GB637142A - Improvements in and relating to three phase magnetic cores - Google Patents

Abstract

637,142. Making magnetic cores. BRITISH THOMSON-HOUSTON CO., Ltd. Jan. 19, 1948, No. 1608. Convention date, Jan. 18, 1947. [Class 83 (ii)] [Also in Group XXXV] A magnetic core comprises at least one multiturn spiral member of magnetic material and at least one laminated leg member formed of magnetic strip material, at least some of the leg lamination ends being interleaved between the spiral member turns. Fig. 1 shows a 3- phase core comprising three straight legs 1, 2, 3 having alternately long and short laminations and yokes 4, 5 interleaved with the ends of the long laminations of the legs at spaced parts of the turns. The yokes are formed by winding a long strip of magnetic material with short spacers placed between the turns at three symmetrically-spaced locations separated by 120 degrees. When the yokes are completed and the spacers removed, the spaces between the turns thus provided accommodate the ends of the long laminations of the legs. The legs have a cruciform cross-section and the interleaved joints between the yokes and the legs are also cruciform in section. Fig. 5 shows a modified form in which the leg portions 13, 14 are combined with a U-shaped member 15. The loop with legs 13, 14 is formed by winding a long strip of magnetic material with spacers inserted between the turns at two opposite ends after which it is then cut into lengths of, say, two turns each. This loop is assembled by lacing the cut pieces through coils 16, 18 after which the member 15 is inserted in a winding 17 by lacing its individual laminations through the window of the winding 17.