Polyphase Patents

The Westinghouse Electric & Manufacturing Company has announced in connection with the expiration this week of the three fundamental Tesla patents, that it holds numerous other patents relating to polyphase synchronous motors and subsidiary apparatus. Seven of these patents were granted to Nikola Tesla on dates between September 3, 1889, and January 2, 1894, the subjects being as follows: Induction motors; the use of the induction motor as a starting device for the synchronous motor; relation between the number of poles on generator and motor, and four patents on the split-phase method of operating motors. Three of the list of patents were granted to Hutin and Leblanc, the subjects being damping devices for alternating-current motors, variable-speed induction motors, and alternating-current transformation. Nine patents were granted to Mr. B. G. Lamme, the subjects being induction motors, starting arrangements for induction motors, and alternating-current motor. Of the remaining patents, two were granted to Mr. William Stanley for an alternating-current motor with compensated field and a self-regulating transformer (1892), another to Nolan for armature core construction and two others to Dusinberre for induction motors.