The story of the induction motor

This paper covers the history of the technical side of the development of the induction motor, principally as the author saw it. It indicates the various stages of development from the early Tesla motor, with polar field construction, to the distributed field construction, and from the early wound-rotor type to the later almost universal cage type. Reference is made to the development of the cage motor with high starting torque, and the reasons which led up to it. The early single-phase induction motor is also treated, indicating various stages in its development. The latter part of the paper covers the growth of the motor as an industrial apparatus and its application to various unusual services, such as heavy mill work, locomotive operation, ship propulsion, etc. Speed control of such motors is also described. The papers refers, principally, to American practise, although occasional reference is made to foreign work. The description covers, primarily, the development work of the company with which the writer is connected, and reference to the work of other companies is incidental, due, largely, to lack of sufficient inside data.