GB807967A - Improvements in or relating to induction motors - Google Patents

Abstract

807,967. Squirrel cage constructions. GENERAL ELECTRIC CO. June 13, 1956 [June 14, 1955], No. 18266/56. Class 35. A high electrical resistance squirrel-cage rotor in a high starting torque induction motor 1 comprises a cylindrical stack of magnetic laminations 10 having two sets of spaced passageways 13, 15 extending therethrough in directions parallel or substantially parallel to the central axis of the stack one set 13 being adjacent the cylindrical outer periphery 14 of the stack and the other set 15 being at a substantially greater radial distance from the periphery 14 than the set 13, and a mass of cast electrically conductive material filling all the passageways and forming at each end of the stack an end ring 19 joining all the bars 17, 18 formed by the passageway fillings, the passageways 15 being sufficiently deep within the stack that substantially no current flows in its bars 18. The latter of large cross-sectional area, provide the mechanical strength to hold the laminations together while the bars 17, of small crosssectional area, carry the bulk of the current to produce the motor torque; the cast material may be aluminium. The ends of the stack may comprise laminations 11 which are similar to laminations 10 but have larger openings 16 to provide a transition area between bars 17 and end rings 19. In a modification, not shown, the radially aligned openings in these end laminations are formed into radial slots.