GB190606195A - Improvements in and relating to Alternating Current Dynamo Electric Machines. - Google Patents

Abstract

6195. British Thomson-Houston Co., [General Electric Co.]. March 14. Armatures; field magnets; sparking, preventing. -In self - exciting alternating-current machines having a commutator which rectifies superposed shunt and series currents from the armature for field excitation, as described in Specification No. 24,874, A.D. 1904, the auxiliary armature winding described in Specification No. 16,518, A.D. 1905, for the field current has its reactance reduced by the application of a short-circuited winding to the field magnet in inductive relation to the auxiliary winding. The short-circuited winding is particularly applicable to machines with laminated or with cylindrical field magnets. Within slots in the armature are wound the main armature coils A and the auxiliary coil a, which are held in position by suitable wedges. Upon the field magnet F<1>, shown as of the cylindrical type, are wound the field coils F, carried in slots in the field magnet. The field magnet is also provided with a shortcircuited distributed winding f in inductive relation to the auxiliary winding so as to act as a lowresistance short-circuited secondary to reduce the reactance of the auxiliary winding. This shortcircuited winding may be formed as shown by short-circuiting a few of the turns of the field coil and winding some of these short-circuited turns around the portions of the field magnet between the poles.