GB357225A - Improvements in and relating to dynamo electric machines - Google Patents

Abstract

357,225. Dynamo-electric machines. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Wieseman, R. W.; 1, Rosa Road, Schenectady, New York, U.S.A.) June 18, 1930, No. 18634. Convention date, June 21, 1929. [Class 35.] In a synchronous or other dynamo-electric machine in which the number of field-magnet poles is to be changed, the field element consists of one or more salient-pole units, each composed of four large poles and four small poles arranged in pairs, the small poles having magnetically symmetrical pole-tips facing each other. All the poles are provided with windings and are divided into two groups, the direction of the current in one group being reversible, in such a manner that the number of poles is changeable from 2N to 3N, N being an even number. In the arrangement shown, the revolving field magnet comprises one or more units, according to the desired number of poles, each comprising four large and four small salient poles 2, 3 respectively, with windings which are divided into two groups, one group being connected to the slip-rings 4 and the other to slip-rings 5. The polarity of the poles connected to the slip-rings 4 is constant, but the polarity of the other group may be reversed by the switch indicated, thus changing the polarities from the lettering shown at the top of the poles to that indicated at the bottom. The small pole-tips are sloped as indicated in Fig. 3, and the cross section of two small pole cores should equal that of one large pole core. The invention is applicable to water-wheel driven generators and to ship-propulsion motors. Specifications 25858/03 and 196,750, [both in Class 35, Dynamo-electric generators &c.], are referred to.