In 1889, repeating Hertz's experiments, I found high-frequency current overheated a Ruhmkorff coil. I replaced its insulation with an air gap and a movable iron core, and patented the result in 1891.
In July 1888 my backers negotiated a licence of my polyphase motor and transformer designs to George Westinghouse for $60,000 in cash and stock plus $2.50 per AC horsepower. In 1891 I released the company from that royalty to keep it championing the motor.
In 1887 I developed an induction motor that ran on alternating current, using polyphase current to make a rotating magnetic field. I patented it in May 1888 and demonstrated it at the American Institute of Electrical Engineers.
I am an electrical engineer, inventor and futurist. My engineering work on the induction motor and the polyphase system helped design the modern alternating current (AC) electricity supply.
