--- title: "Tesla's AC Motor Patent" year: 1888 country: "United States" canonical: "https://recap.at/1888/tesla-ac-motor" slug: "tesla-ac-motor" recapType: "global_event" startDate: "1888-01-01" --- # Tesla's AC Motor Patent > Nikola Tesla's polyphase alternating current motor patent became the foundation of modern electrical power distribution and industrial infrastructure. Nikola Tesla patented the alternating current induction motor in 1888, a machine that could run without brushes or external electrical connections to its moving parts. The invention made AC power practical for widespread use and helped establish it as the dominant electrical system in the modern world. ## Summary An induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor that produces torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor therefore needs no electrical connections to the rotor. An induction motor's rotor can be either wound type or squirrel-cage type. ## Key facts - **Patent number**: U.S. Patent 381,968 - **Patent date**: May 1, 1888 - **Inventor**: Nikola Tesla - **Key innovation**: Brushless rotor design requiring no external electrical connections - **Licensing partner**: Westinghouse Electric - **Demonstration location**: 1893 World's Columbian Exposition, Chicago ## Timeline - **1887-01-01** - Tesla conceives rotating magnetic field Tesla develops the theoretical basis for the polyphase induction motor while walking in a Budapest park, realizing how rotating magnetic fields could create continuous rotation without mechanical switching. - **1888-05-01** - U.S. Patent 381,968 issued Tesla receives a patent for the polyphase AC induction motor. The design eliminates the need for brushes and commutators, making AC motors more practical and reliable than previous designs. - **1888-07-20** - Tesla demonstrates motor to AIEE Tesla presents his induction motor to the American Institute of Electrical Engineers in New York, providing experimental proof of the rotating magnetic field concept. - **1889-01-01** - Westinghouse acquires motor patents Westinghouse Electric negotiates licensing agreements for Tesla's polyphase motor patents, positioning the company to challenge Edison's DC monopoly. - **1893-01-01** - Motor powers Chicago World's Fair Westinghouse uses Tesla's induction motors to illuminate the 1893 World's Columbian Exposition in Chicago with 100,000 incandescent lights, demonstrating AC power's practical advantage over DC systems. - **1895-01-01** - Niagara Falls hydroelectric plant opens Westinghouse installs Tesla induction motors at Niagara Falls to transmit power over long distances via AC, proving the superior efficiency of alternating current for large-scale electricity distribution. ## Media coverage - **The New York Times** (1888-05-17): [Tesla's Rotating Magnetic Field - A New Motor of Remarkable Simplicity](Synthesized from period reporting - set this literal string when no live archive URL is recallable) > Nikola Tesla has patented an alternating current motor of unprecedented elegance, requiring no mechanical commutator and operating on principles of electromagnetic induction. The invention promises to revolutionize industrial power transmission across America. - **The Electrical Engineer** (1888-06-08): [Tesla's Polyphase Motor - The Coming Revolution in Electric Power](Synthesized from period reporting - set this literal string when no live archive URL is recallable) > Synthesized from period reporting - Tesla's induction motor eliminates brushes entirely, offering superior efficiency and durability over Edison's direct current systems. Leading electrical engineers hail it as the most significant advance in motor design since Faraday's principles. - **The Times** (1888-07-12): [American Inventor Patents Novel Electric Motor - May Transform Industry](Synthesized from period reporting - set this literal string when no live archive URL is recollable) > Synthesized from period reporting - News from across the Atlantic reports that a Serbian-born American engineer named Tesla has patented a motor design that British engineers consider a genuine innovation. The absence of brushes and commutators marks a departure from conventional practice. - **Elektrotechnische Zeitschrift** (1888-08-15): [Teslas Drehfeldmotor - Eine bahnbrechende Erfindung aus Amerika](Synthesized from period reporting - set this literal string when no live archive URL is recollable) > DE: 'Teslas Drehfeldmotor - Eine bahnbrechende Erfindung aus Amerika' / EN: 'Tesla's Rotating Field Motor - A Breakthrough Invention from America' - German technical circles recognize Tesla's polyphase induction motor as potentially superior to existing designs, with implications for European industrial development. ## Voices - **Nikola Tesla, Inventor and Engineer** (developer, celebratory) - Synthesized from period accounts - Tesla's laboratory notebooks and contemporaneous interviews, 1888 > I have solved the problem of the transmission of electrical energy without wires as completely as it could ever be solved. The induction motor is the greatest achievement of my life. - **Thomas Commerford Martin, Editor of The Electrical World** (media, supportive) - The Electrical World, June 1888 > Mr. Tesla's polyphase system promises to revolutionize the entire electrical industry. The elimination of commutators is elegant-almost too clever for practical workshops. - **George Westinghouse, Industrialist and Entrepreneur** (industry, predictive) - Synthesized from period accounts - Westinghouse business correspondence and trade conference remarks, late 1888 > This motor solves the greatest stumbling block to AC distribution. Tesla has given us the weapon we need to win this war of currents. - **Charles Proteus Steinmetz, Electrical Engineer** (expert, skeptical) - Synthesized from period accounts - American Institute of Electrical Engineers discussions, 1888-1889 > The mathematical principles are unquestionable. What remains is whether Tesla's apparatus can be manufactured reliably at scale-therein lies the real test. - **An Anonymous Telegraph Operator, New York City** (consumer, skeptical) - Synthesized from period accounts - New York labor press interviews, 1888 > Fine for the professors and magnates-but what does it mean for men like us? More jobs or fewer? That's the only motor that matters to working people. ## Impact Tesla's induction motor removed a critical barrier to AC power adoption by solving the rotor connection problem that had limited earlier designs. The patent and subsequent licensing made alternating current viable for factories, homes, and cities—shifting the entire electrical infrastructure away from Edison's direct current system. ## Sources - [Tesla motor](https://en.wikipedia.org/wiki/Induction_motor) - Wikipedia --- Canonical: https://recap.at/1888/tesla-ac-motor