GB311341A - Improvements in and relating to dynamo-electric machine windings - Google Patents

Abstract

311,341. British Thomson-Houston Co., Ltd., (Assignees of Chase, D. D.). May 9, 1928, [Convention date]. Void [Published under Sect. 91 of the Acts]. Windings.-The armature winding of a dynamo electric machine .consists of a number of independent circuits with the coil sides of the different circuits interspersed in different slots. The circuits may be wound for different voltages or numbers of phases or may be operated independently or connected in parallel if they are exactly similar. The invention is particularly applicable in the case of a synchronous alternating current generator, the. winding of which comprises two parts or circuits, which can supply equal or unequal loads to different external circuits, the parts being magnetically coupled in a manner to introduce reactance between the separate circuits and permit power to flow therebetween within safe operating limits. Fig. 1 shows a two layer lap winding for a two pole, two circuit, threephase alternator. The winding coils are shown as having a fractional pitch and the three phases of one are A1-A4, A2-A5 and A3-A6, while the three phases of the other circuits are B1-B4, B2-B5 and B3-B6. The common terminals A4, A5, A6 and B4, B5, B6 may be arranged to connect the winding parts in star or delta. The winding parts A and B are located in alternate slots, and in order to avoid the effect of the two voltages being out of phase by an angle corresponding to one slot pitch, the lead of the circuits is alternated in adjacent phase belts. For example, as shown in Fig. 2 which shows phase A2-A5 of one winding and phase B2-B5 of the other, the coil sides of the two circuits are arranged in alternate slots, but whereas the first slot 9 in the phase belt in the centre of the Figure is occupied by a, coil side of circuit A, the first slot 21 in the succeeding phase belt is occupied by a coil side of circuit B. Instead of disposing the sides of the two winding parts in alternate slots, two coil sides of one part located in adjacent slots may be succeeded by two coils of another circuit of corresponding phase in the next two adjacent slots. In the case of machines having a number of poles greater than two the leads of the circuits in adjacent phase belts may be varied, for example, one circuit may lead under two poles, or lag under two succeeding poles. The machine may be used to interconnect bus sections of bus-bar systems in generating or sub-stations or it may be used as a synchronous motor, starting being effected with one winding only or with both windings in series.