GB471113A - Improvements in or relating to induction motors - Google Patents

Abstract

471,113. Induction motors. WALSH, A., and METROPOLITAN - VICKERS ELECTRICAL CO., Ltd. Feb. 22, 1936, No. 5395. [Class 35] In order to produce an effect similar to that resulting from cascade connection of two induction motors, the rotor of squirrel-cage motor is made in two parts co-operating with two stators and the parts of the conductor bars lying within one stator are connected with those lying within the other stator in such order that the currents produced in the bars by the rotating field produced by one stator will produce between the other stator and the part of the rotor therein a field rotating in the opposite direction to the first field. The first part of the stator is supplied with current in the ordinary way, and the second may be short-circuited, either directly or through an adjustable resistance, or may be connected to a phase-advancer or other exciter, or the second stator may be a solid mass of magnetic material. Fig. 2 shows an arrangement of the rotor bars in which the bars 1 ... 8 in one half of the rotor extending over a pole pair pitch are connected in reverse order to the bars 1<1> ... 81 of a corresponding portion of the other part of the rotor. The bars extending over a single pole-pitch may also be similarly connected, so that the two rotating fields are displaced with respect to each other by a pole-pitch. Fig. 4 shows an arrangement in which the bars through a single pole-pitch are reversely connected as above, but one bar in each pole-pitch is in alignment with the bar to which it is connected in the other part of the rotor, thus producing a further displacement of the fields. Fig. 7 shows an arrangement in which the number of slots in one of the rotor parts B is double that in the other part A. The conductor in one of the slots of part A such as the slot 201 divides into two portions passing to two slots 20 of the part B spaced by an amount equal to a pole-pitch of the part A or a pole-pair-pitch of the part B. The connections intercross as shown to produce the effect of reversing the direction of rotation of the field as described.