GB359988A - Improvements in and relating to dynamo electric machines - Google Patents

Abstract

359,988. Dynamo-electric machines. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Taylor, H. D.; 1358, Dean Street, Schenectady, New York, U.S.A.) May 20, 1930, No. 15492. Convention date, May 20, 1929. [Class 35.] Cores.-In a salient pole dynamo-electric machine, open unwound slots are provided in the periphery of the poles to reduce noise due to variations in the radial magnetic pull between the two members of the machine. These slots are so situated as to minimize the variations of the reluctance of the magnetic path from the peripheral portion of the pole to the corresponding part of the core of the other member for all the relative positions of the salient pole and non-salient pole members. In the form shown in Figs. 3 and 4 variation of the flux path is caused by the slots 17 which are only ineffective when the salient pole 13 is in the position shown in Fig. 3. This variation is counteracted by empty slots 18 spaced approximately half a tator tooth pitch from the slots 17. In the form shown in Figs. 7 and 8, the flux distribution is disturbed by the slots containing the conductors 20 when the pole 19 is in the position shown in Fig. 7, which is also the position when the pole is presented to the minimum number of teeth. Fig. 8 shows the pole 19 moved through half a stator tooth pitch so that the pole is opposite four teeth 16. To counteract these inequalities, the conductor containing slots are plugged with magnetic material 23 and empty slots 24 are provided which are only effective when the number of teeth opposite the pole is greater than the mean number. When a pole without a pole-face winding is used, unwound open slots are provided so as to be effective when the pole is opposite the larger number of stator teeth, the slots being approximately a stator tooth pitch apart. Reference has been directed by the Comptroller to Specifications 104,535 and 232,794, [both in Class 35, Dynamo-electric generators &c.].