GB223924A - Improvements in and relating to induction motors and the like dynamo electric machines - Google Patents

Abstract

223,924. British Thomson-Houston Co., Ltd., (Assignees of Maxwell, H.). Oct. 24, 1923, [Convention date]. Alternating-current induction machines; conductors.-Motors of the squirrel-cage type have conductor slots in the rotor containing a highresistance winding and a low-resistance winding provided with common end-rings, the highresistance winding being permanently closed by the end rings, and means co-operating with the high-resistance winding to close the lowresistance winding gradually as the motor speeds up. The low resistance conductors 15 and the high-reistance conductors 14 are separated from each other in the slots by insulation 19, but are permanently connected at one end to a common end-ring 18. The conductors 14 are of elastic metal and their free ends are bent so that the outer conductors contact permanently with the end-ring 16 and the inner ones with an expansible ring 20 and together keep the free ends of the low-resistance bars 15 out of contact with the rings 16, 20 at low speeds. As the motor speeds up, centrifugal weights 21 mounted on a slidable pivot 22 expand the ring 20 which gradually presses the bars 15 into contact with the ring 16 through the resilient ends of the conductors 14.