Italian physicist and electrical engineer. He is noted for his work on alternating current and for his discovery (1885) of the rotary magnetic field, through which he promoted the development of alternating-current motors.
Galileo Ferraris was born in Livorno Vercellese, in what is now northern Italy, on October, 3, 1847. He was one of four sons of a pharmacist. At the age of ten he went to live in Turin with an uncle physician , who guided the boy’s education in sciences. He spent three years at the University of Turin and two years at the Application School (Scuola d’Applicazione) of Turin. In 1869 he took the degree in Engineering; his thesis was on propagation of electricity in homogenous solids.
He was soon appointed as an assistant at the Museo Industriale of Turin, one of the educational institutions that merged in 1906 to form the Politecnico di Torino. While teaching physics he conducted research into light and optics, and the study of optical phase differences in light waves led him to look into similar phenomena in other forms of radiation, including magnetism. In 1877 he was given charge of the course on technical physics at the Museo Industriale, and in 1879 he became a full professor, remaining there until his death in 1897.
He believed strongly that his engineering students should combine theoretical study with practical experimentation, and in 1882 established the “School of Electrotechnology with Laboratory” at the Museo Industriale. He always placed special emphasis on the importance of electrical measurements. One of his earliest papers recorded measurements of the minimum current needed to produce audible signals in a telephone receiver.
When the first International Electrical Exhibition was held, in Paris, in 1881, Ferraris was sent as one of the Italian Government’s representatives to the associated Congress of Electricians. He was a prominent figure in the Exhibition, and he took an active part in the debates at the congress. From that time onward his main technical interests were the increasing number of applications of electricity. In 1883 he again represented his Government, this time at the electrical exhibition held in Vienna.
By 1884, Italy, still a young country having only been united since 1861, wanted its own International Exhibition. This was held at Turin, which had been the first capital of Italy. Ferraris was made President of the Electrical Department of the exhibition. At the exhibition he carried out a practical study, with careful measurements, of the Gaulard and Gibbs transformers that were exhibited.
These had been used for supplying the electric lighting on the London Underground, and during the exhibition a pair of transformers was used in a demonstration of electrical transmission over a distance of about 40 km from Turin to Lanzo. The power was low, only a few kilowatts, but the demonstration was a significant development in electrical engineering.
The device presented here is the one on which G. Ferraris carried out his experiments in 1884. Its iron core is still open. The two windings consist of copper sheet flat rings, 0.25 mm thick, cut at a certain point of the circumference and provided with projections at both ends. The rings are inserted on an iron wire core and are insulated one from the other by means of paper or varnish.
The projections of the next rings are shifted along the circumference in order to form a spiral. Afterwards the projections are metallically connected alternating the rings and this forms the primary winding. The secondary winding is obtained in the same way; this connection stops at one fourth of the column and the two ends are taken out; the process continues with the second fourth of the column and so on, so that the secondary winding is subdivided in four sections, that may in turn be connected in series or in parallel one to the other, with reference to the output line, by means of the plugs arranged on the front side.
In this way it’s possible to have on the secondary winding a voltage and a current different from the ones feeding the primary winding. In the present model the primary winding has 455 rings, as many as the secondary winding. Nowadays it’s possible to detect the main faults of this device: large reluctance of the iron-air magnetic circuit; small area of the iron core section; weak insulation of the turns which doesn’t allow to reach high operation voltages; small ratio between the primary and secondary turns number, even connecting all of the secondary sections in parallel.
At that time little was understood about the theory of transformers, and there were no published studies of their efficiency, so Ferraris’ work attracted considerable interest. The following year he carried out similar studies on the transformers of Zipernowsky and others, which had closed iron cores wheres the Gaulard and Gibbs transformers had an “open” magnetic circuit with the flux path completed through the air.
At the time of the Turin exhibition electricity was used almost exclusively for lighting, but people were beginning to think about electric motors. The idea that a rotating magnetic field might cause a suitable “rotor” to revolve was not new. Walter Baily, for example, had exhibited in London in 1879 a device in which two sets of electromagnets were switched alternatively causing a copper disc to rotate. Ferraris’ transformer studies led him to consider the fact that the primary and secondary currents were out of phase. In the summer of 1885 he conceived the idea that two out-of-phase, but synchronized, currents might be used to produce two magnetic fields that could be combined to produce a rotating field without any need for switching or for moving parts. This idea, which is common place to electrical engineers now, was a complete novelty in the 1880s. Ferraris published it in a paper to the Royal Academy of Sciences in Turin in 1888. This was quickly translated into English, and published in the journal Industries, later the same year. In “Il Nuovo Cimento”, Ferraris published 11 papers: 10 on electromagnetism and 1 on electricity.
Ferraris devised a motor using electromagnets at right angles and powered by alternating currents that were 90 out of phase, thus producing a revolving magnetic field. The motor, the direction of which could be reversed by reversing its polarity, proved the solution to the last remaining problem in alternating-current motors. The principle made possible the development of the asynchronous, self-starting electric motor that is still used today. Believing that the scientific and intellectual values of new developments far outstripped material values, Ferraris deliberately did not patent his invention; on the contrary, he demonstrated it freely in his own laboratory to all comers. Meanwhile, other physicists came independently to the same principle–among them Nikola Tesla, who applied and patented it. Ferraris was also an early advocate of alternating-current distribution systems for electrical power.
At the time Ferraris seems not to have thought that his principle would lead to a motor for industrial purposes, but he did suggested that it could be used as the basis of a meter for alternating current measurements. In 1891, however, he attended the Electrical Congress at Frankfurt where three-phase transmission was demonstrated over a line from Lauffen, more than 100 miles distant. At the Congress Dinner Ferraris was hailed as “the father of three-phase current.”
The models shown here are not the original devices, designed and made by G. Ferraris. In 1899 the original models (along with other devices and papers of Galileo Ferraris’s) were sent to the “Esposizione Nazionale Elettrica e di Prodotti serici” (National Electrical and Silk Products Exhibition), organized in Como to celebrate the centennial of the discovery of Volta’s pile. They were almost completely destroyed in the fire on the exhibition, on July 8, 1899, along with Volta’s historical apparatus.
The few scorched remains were placed in G. Ferraris’s old office in the “Politecnico di Torino” and were definitely destroyed in the Politecnico fire, due to a bombing, on December 9, 1942. After the 1899 fire the destroyed models were re-made by Prof. Guido Grassi, G. Ferraris’s successor at the Turin School and according to an oral tradition, by the same artisan who had made the original devices 14 years earlier. Two of them still bear the tags written by Prof. Grassi. They escaped the fire of 1942 because they were kept in the “Istituto Elettrotecnico Nazionale”.
Ferraris universal indicator (Voltammeter, Ammeter and Wattmeter) for balanced three-phase loads produced by Siemens & Halske. The Ferraris rotating field instruments were released on the market by Siemens around 1900. This column-shaped model, with 400 A, 6500 V and 4000 kW range, very probably comes from the Thermal Power Plant called “Martinetto”, owned by the Torino Municipality, and was used for one of the two turboalternators installed there, each one of the power of 3100 kVA.
Although his laboratory work was vital to him, Ferraris found time to use his abilities as an engineer in the service of the wider community. In 1897 he became a city councillor in Turin and proved to be an active councillor especially where his technical knowledge could be of use. Naturally he was closely involved with the electric street lighting of Turin, and he was concerned that the lighting should include the suburbs as well as the city center. Turin had long had horse-drawn trams, and when electric trams powered by accumulators were proposed Ferraris resisted that idea, preferring a tramway system with electrical distribution by either overhead or underground conductors.
Because of his “social” concerns, he argued that electric power should be distributed as widely as possible and available to everyone. He argued, for example, that with electric power in the home a mother might earn money by working at home with a loom, rather than “abandoning her children” by going out to work.
Ferraris died in Turin on February, 7, 1897 at the age of 50. Both for his contributions to electrical engineering and for his work to make the benefits of electricity widely available, Galileo Ferraris deserves to be remembered as one of the great names in connection to electricity.
He has been:
Assistant of Prof. Codazza at the Royal Industrial Museum of Turin (from 1870)
Doctor at the Faculty of Physical, Mathematical and Natural Sciences at the University of Turin (from 1872)
Teacher of Industrial Physics at the Royal Application School of Turin (from 1877)
Professor of General Physics at the War School (1877)
Professor at the Application School of Engineering of Turin (from November, 1, 1878)
Delegate of the Italian Government in the jury at the International Electricity Exposition at Paris (1881)
Delegate to the Paris Conference on electrical units standards (1882 )
Italian delegate to the Electrical Exposition in Vienna (1883)
President of the International section of the Electricity Exposition in Turin (starting from 1883)
Director of the electro-technical laboratory of the Industrial Museum of Turin (from December, 16, 1888)
Vice-President of the Electrical Exposition in Chigago in 1893 where the henry, the joule and the watt have been adopted
Italian delegate at the Congress of Geneve (summer 1896)
Senator of Italian Reign (October, 21, 1896)
One of the founders of the Electrotechnical Italian Association in Milan on December 1896
President of Metrical Italian Commission (from 1897)