GB546862A - Improvements in or relating to electric induction motors - Google Patents

Abstract

546,862. Rotor windings for induction motors. SCHWARZ, B. Dec. 30, 1940, No. 18224. [Class 35] A rotor winding for an induction motor comprises a number of winding elements each of which includes three conductors two of which, 4, 5, lie respectively in the upper and lower halves of slots 8, 9 near the periphery of the rotor and form a double layer low reactance winding of shortened pitch, whilst the remaining conductor 7 lies in a deep slot 10 and forms in series with the other conductors a high reactance winding. The conductors may be joined to a common short circuiting ring 3. Each group of conductors may be formed by splitting a thick bar 1 the split extending over any desired length of the end connection 6, or by placing two conductors bent to form loops of different widths upon each other and soldering them together to form the third conductor, Fig. 2 (not shown). In a further modification, Fig. 3, the third conductor is formed in two parallel-connected parts 20, 21 which lie in slots 22, 221 situated at different depths in the rotor core. Other modifications are described involving different slot arrangements and the use of pairs of winding elements in which the pitch between the high reactance and low reactance conductors of one element of a pair differs from the corresponding pitch of the other element.