GB341518A - Improvements in electrical generating machines to give drooping voltage characteristics of the same nature at varying outputs - Google Patents

Abstract

341,518. Dynamo-electric machines. GREENWOOD & BATLEY, Ltd., Albion Works, Leeds, and CARRICK, J. H., 7, Hvde Park Road, Harrogate. Oct. 17, 1929, No. 31522. [Class 35.] Exciting.-In a drooping characteristic dynamo having a series excited auxiliary field system in opposition to the shunt or compound main field, the main brushes are arranged substantially diametrically opposite one another on the commutator and an additional pair of brushes is arranged at points corresponding to points on the armature lying within the effective path of the main flux whereby the main shunt field winding which is energized from these brushes is excited at a voltage due substantially wholly to the main flux and which is substantially constant at all loads. In the form shown, the main poles 4 carry a winding 10 connected to the brushes 8, 9 the voltage across which is due to the main flux only. A cumulative compound winding is also placed on the poles 10. The auxiliary poles 5 are series wound and oppose the main poles, the voltage across the main brushes 6, 7 being, therefore, that due to the resultant of the main and auxiliary pole fluxes. The voltage may be adjusted by tapping the coils on the poles 5 or by using a diverter in conjunction with these coils. In a modified form, the compound main winding may embrace both the main and auxiliary poles. The auxiliary poles will then aid the main poles at no load but will require more series ampereturns. Commutating poles may be used if desired.