GB373603A - Improvements in and relating to dynamo electric machines - Google Patents

Abstract

373,603. Dynamo-electric machines. INTERNATIONAL GENERAL ELECTRIC CO., Inc., 120, Broadway, New York, U.S.A. -(Assignees of Allgemeine Elektricitõts- Ges. ; 2, Friedrich Karl-Ufer, Berlin.) Feb. 20, 1931, No. 5424. Convention date, Feb. 21, 1930. Drawings to Specification. [Class 35.] Motors with unwound iron armatures inductor alternators ; rotary transformers.-The laminated stator and rotor of a dvnamo-electric machine are provided with different numbers of open slots, the quotient of the two numbers differing from a whole number, and the ratio of slot width to tooth width on both stator and rotor is so selected that zones of high magnetic conductivity and zones of low magnetic conductivity are formed at the air gap. The slot width may be the same as the tooth width in both stator and rotor, or the tooth may be slightly narrower than the slot at the outlet. The number of slots on both members is preferably even. If a rotary field is produced in the stator, the speed of the rotor will be given by the formula n = 120 V (Zr -Zs) #P Zs where V is the supply frequency, P the number of poles and Zr and Zs the number of rotor and stator teeth respectively. By providing a winding on the rotor, currents will be generated therein having a frequency V1 = (nf-nr)#120 P where nf and nr are the speeds of the rotary field and the rotor respectively, and the machine functions as a rotary transformer in which the secondary frequency is slightly greater or less than the primary frequency. The two frequencies may be superimposed, e.g. by means of a transformer to produce a very low beat frequency. Single-phase motors may be started by the provision of an auxiliary phase including a condenser. The machine may operate as a high frequency generator. Reference has been directed by the Comptroller to Specifications 13888/15, 14160/15, 14377/15, and 101,447, [all in Class 35, Dynamo-electric generators &c.].