GB191026984A - Improvements in Single-phase Alternating-current Motors. - Google Patents

Abstract

26,984. Haigh, B. Parker-. Nov. 21. [Cognate Application, 9957/11.] Alternating-current commutator machines.-A single-phase motor is provided with stator windings arranged for two different numbers of poles in the ratio of two to one, the motor being used alternatively as a compensated series, repulsion, or compensated repulsion motor when running. with one or both numbers of poles. The armature winding is given a coil-step intermediate between the lengths of the stator pole pitches. The field excitation may be produced either by special stator windings, or by suitably arranging the main or the auxiliary brushes. Independent inducing or compensating, and exciting windings may be used for each number of poles; or single windings may be employed. Each single winding may consist of two parts, which are connected in series for 2n-pole operation; for n-pole operation, the two parts are connected in parallel so that the current in one part is reversed. Extra compensating or inducing windings may be placed in some of the stator slots. Fig. 5<a> shows a four-pole exciting-winding A, B, C, D, and Fig. 5<b> shows the same winding reconnected for two-pole operation. The corresponding connexion-diagram is shown in Fig. 9, and the sections CWA, CWB of the inducing-winding, the four parts A, B, C, D of the exciting-winding, and the armature A being joined up as shown. On closing switch R alone, the motor runs as a 4-p-pole repulsion motor; on closing switches CR alone, the motor is changed to a 2-p-pole compensated-repulsion machine. The motors are started by gradually increasing the voltage impressed upon them. Some forms of the motors may run on direct-current circuits.