GB746930A - Improvements in or relating to electric motors - Google Patents

Abstract

746,930. Split-phase induction motors; transformers. HUTCHINS ELECTRIC CO., Inc. June 23, 1954 [Sept. 9, 1953], No. 18485/54. Classes 35 and 38 (2). A split-phase motor without starting switch, has main and auxiliary windings a, b, the common point 4 and the free end of the auxiliary winding being connected through transformer windings t2, t1 to the supply line. Transformer winding t1 has about three times as many turns as t2, and motor winding a has about four times as many turns as b. Thus the winding t1 which carries the currents of both windings a and b governs, through secondary winding t2, the amount and phase of the current flowing in the auxiliary winding b. It is advantageous to proportion the transformer core so that it is saturated at starting but not during running. The transformer may be mounted round the motor shaft inside the motor shell, and is composed of windings 30 embraced by a series of annular cup-shaped laminµ 26 of progressively greater diameter nesting together, a hole being provided for the conductors 34. In a modification the stator core is used as a transformer core, slots being provided in its outer surface to carry the transformer windings which pass, together with the motor windings, through certain of the internal stator slots. Specifications 716,453 and 740,136 are referred to.