GB359207A - Improvements in or relating to electric motors - Google Patents

Abstract

359,207. Induction motors. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London, and SAUNDERS, N. F. T., of General Electric Co., Witton, Birmingham. Oct. 21, 1930, No. 31539. [Class 35.] The bars of a squirrelcage motor having stator windings adapted to give different pole numbers are divided into groups so connected through resistances that when the motor is running on a low-pole number the effective resistance of the winding is greater than when running on a high-pole number, the object being to give more effective braking in motors used for lifts and like purposes. Fig. 1 is a diagram of connections for a motor having 32 bars and stator windings for four and eight poles. The bars are divided into groups of eight alternately connected to end rings 5, 7 at one end and 6, 8 at the other, the end rings being connected through resistances 9 .. 12. The single arrows show the course of the current when the motor is running on four poles and the double arrows when it is running on eight. Fig. 4 shows the construction of the connections. The bars 53 of one set project beyond those of the other and are braced to a ring 49. The bars of the other set are connected to a smaller ring 50 through arcuate packing pieces 56. The resistances are constituted by strips of sheet metal 52 extending from a ring 51 to the rings 49, 50. Connections for a motor having 32 bars and four, eight, or sixteen poles are also described.