GB406777A - Improvements in and relating to electric motors - Google Patents

Abstract

406,777. Induction machines. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Morrill, W. J. ; 2317, South Wayne Avenue, Fort Wayne, Indiana, U.S.A.) Sept. 28, 1932, No. 26966. Convention date, Sept. 29, 1931. [Class 35.] A single phase motor has displaced primary windings which are energized in parallel for starting one of which produces a sinusoidally distributed flux and another a flux having a large non-fundamental component, and a secondary winding which is responsive only to sinusoidally distributed primary flux, and means are provided to cause the primary member to produce fluxes only of substantially sinusoidal distribution for running conditions. In the form shown in Fig. 7, the main primary winding consists of sections 11, 12 both of which are used for running but 11 only for starting, and the auxiliary primary winding consists of sections 30, 31 parallel connected for running section 30 only being used for starting, whilst the secondary 14 preferably consists of short circuited coils in skewed slots connected at one end to a common end ring, the coils having a pitch approximately ten fourteenths that of the full pitch coil section 11 of the primary. The sections 11, 12 are wound in the same axis, have the same effective number of turns, but whereas 11 is a concentrated full pitch coil arranged so that it produces an approximately uniform flux across the pole, winding 12 is so arranged that it produces a flux which when combined with the square wave flux of winding 11, produces a substantially sinusoidal resultant, and as the secondary is non-inductive to non-sinusoidal fluxes, the arrangement is equivalent to series reactance in the main winding circuit for starting up. The auxiliary winding section 30 produces high leakage fluxes when used alone and the voltage across the condenser is thereby raised; alternatively however, the condenser may be in series with a single auxiliary section permanently in circuit, or the condenser may be omitted and the auxiliary winding disconnected on reaching normal speed. As a further alternative, winding 27, Fig. 6, is similar to winding 11, Fig. 7, and is connected in parallel with a sinusoidal flux producing winding 28 for starting but is subsequently disconnected.