GB557968A - Improvements in and relating to dynamo electric machines - Google Patents

Abstract

557,968. Dynamo-electric machines. MANDL, A., and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. Jan. 6, 1942, No. 224. [Class 35] Two or more poles 4, 5, Fig. 1, are excited by windings 8, 9, each pole having nine slots a ...i, j ... r respectively. The rotor has 24 slots with a pitch slightly less than the stator pitch, so that movement of the rotor through one rotor slot pitch causes a region of maximum flux concentration to travel right across each pole. The induced windings are in four groups, A ... D, Fig. 3, each group comprising concentric windings' with alternate coils wound oppositely ; groups which in any position of the rotor have the same inductance are connected in parallel to reduce armature reaction. In Fig. 3, A and C are in series and are connected in parallel with the series-connected groups B and D. The common terminal of groups A, C is shown connected to the common terminal of the groups B, D, at the same potential, but this is not essential. In an alternative all the windings are connected in parallel. The rotor may carry a D.C. winding; the D.C. output may then be controlled by varying the excitation, while the high-frequency A.C. output is controlled by a series resistance. Specification 14377/15, [Class 35], is referred to. According to the Provision Specification the pitch of each pole is 150 degrees, and all the windings may be connected in series; in a further modification, one winding may extend from slot e to slot a, thus embracing half the stator, and other coils may be in planes parallel to this, e.g. slot h to slot k.