Galileo Ferraris (31 October 1847 – 7 February 1897) was an Italian physicist, electrical engineer, and university professor. He is recognized as one of the pioneers of alternating‑current (AC) electrical power systems and the independent inventor of the induction motor.
Early life and education
Ferraris was born in Livorno Vercellese, then part of the Kingdom of Sardinia. He pursued a technical education, obtaining a master’s degree in engineering, and began his career as an assistant in technical physics at the Royal Italian Industrial Museum (later incorporated into the Politecnico di Torino).
Scientific contributions
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Rotating magnetic field – In 1885 Ferraris experimentally demonstrated the principle of a rotating magnetic field produced by two stationary, perpendicular coils supplied with alternating currents displaced by 90°. This concept underlies the operation of induction motors.
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Induction motor – Building on the rotating‑field principle, Ferraris developed the first practical AC induction motor (often called “Ferraris’ motor”). He published his findings in a paper to the Royal Academy of Sciences in Turin on 11 March 1888, contemporaneously with Nikola Tesla’s work in the United States.
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Polyphase alternators and transformers – Ferraris designed alternators that converted mechanical rotation into polyphase alternating current, facilitating efficient long‑distance power transmission. He also authored a comprehensive monograph on open‑circuit transformers based on the designs of Lucien Gaulard and John Dixon Gibbs.
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Optical research – Beyond electricity, Ferraris investigated dioptric (optical) instruments, producing detailed analyses of geometric optics for uncentred lens systems.
Academic and professional roles
From 1889 Ferraris taught at the Italian Industrial Institution, the first Italian school of electrical engineering, which later became part of the Politecnico di Torino. In 1896 he helped found the Italian Electrotechnical Association and served as its first national president.
Honours and legacy
- The “Ferraris disk” motor, a type of induction‑disk motor, bears his name.
- Turin commemorated him with monuments, a dedicated avenue, and a permanent exhibition at the Royal Industrial Museum.
- In January 2021 the IEEE Milestones program recognized Ferraris for “Rotating Fields and Early Induction Motors, 1885‑1888.”
Ferraris died in Turin at the age of 49. His work laid essential foundations for modern AC power distribution and electric motor technology, influencing both industrial practice and subsequent scientific research.
