GB507755A - Improvements in or relating to polyphase transformers and polyphase choking coils - Google Patents

Abstract

507,755. Transformers; inductances. SIEMENS - SCHUCKERTWERKE AKT. - GES. Nov. 16, 1937, Nos. 31510 and 31512. Convention dates, Nov. 16, 1936 and Jan. 18, 1937. [Class 38 (ii)] In polyphase transformer or choking coil arrangements comprising two sets of windings arranged on a common iron core and connected respectively in star and delta or in star and zigzag so that the resultant magnetizing current is free from harmonics, one winding 1, Fig. 1 is arranged on the limbs 2 of the core and the other winding 4 is arranged on the yokes 5. The necessary magnetic circuit for the yoke fluxes may be formed by slotting the yokes, and squirrel cage windings may be arranged in the yoke slots to determine the path of the fluxes. The two windings may be fed from a common supply, or one may be fed from tappings on the other or from an auxiliary winding arranged on the complementary part of the core, Fig. 2 (not shown). In another arrangement, a star-connected winding on the limbs is associated with two sets of deltaconnected windings, one on each yoke, both yokes being subdivided. Fig. 3 shows an arrangement in which the core limbs 22 carrying a star-connected winding 21 are arranged at the corners of a triangle, and at least one yoke 23 is arranged to form a magnetic delta and carries a delta-connected winding 24. Fig. 5 shows a further arrangement in which the deltaconnected winding is distributed over both yokes, one part 87 being on one limb of a singleslotted yoke 98 and the other two parts 88, 89 being on two limbs of a double-slotted yoke 100. The Specification as open to inspection under Sect. 91 comprises also (1) the subject-matter of Specifications 505,778 and 506,073, (2) an arrangement in which star and delta connected windings are arranged respectively on opposite limbs of a core structure having a common unwound limb, and (3) flux-suppressing arrangements comprising short-circuited conducting bars inserted within the slots of subdivided cores. This subject-matter does not appear in the Specification as accepted.