AT THE COMMISSION ON THE HISTORY OF THE PHYSICAL AND MATHEMATICAL SCIENCES OF THE USSR ACADEMY OF SCIENCES

On March 31 in Leningrad, under the chairmanship of Corresponding Member T. P. Kravets, the regular, XXIV meeting of the Commission on the History of the Physical and Mathematical Sciences of the USSR Academy of Sciences took place.

At the meeting a report was heard by Corresponding Member of the USSR Academy of Sciences M. A. Shatelen, “From the History of the Invention of Transformers.” M. A. Shatelen began his report by pointing out that in the recently published first volume of Faraday’s Experimental Researches in Electricity, on one of the first pages of the book there is placed the contemporary drawing by Faraday himself, depicting the iron ring with two windings which is regarded as the ancestor of modern transformers. Faraday’s ring, just like a number of so-called induction coils constructed by many inventors (Page, Wright, and others), was not a transformer in the present-day sense of the word. They were intended for obtaining induction currents, chiefly for medical, physiological, etc., purposes. Likewise, the Ruhmkorff coil and similar devices operating on direct current can hardly be called transformers in the modern sense of the word, although they already have two separate windings and serve to obtain high-voltage current.

The first use of an induction apparatus for purposes of practical electrical engineering was proposed by P. N. Yablochkov, who in 1876 received a French privilege for his invention, and subsequently privileges in other countries as well. Yablochkov used alternating current for his transformer.

current, and used it in exactly the same way as modern transformers are used to supply, from a single generator, a number of different receivers requiring the application of different voltages, provided that the receivers can operate quite independently of one another.

Depending on the required power and voltage, Yablochkov made his transformers of various sizes and with different numbers of turns. At the time the transformer was invented, Yablochkov himself attached no special importance to it, although it was demonstrated both in Paris at three world exhibitions and in St. Petersburg at electrotechnical exhibitions, and in Moscow at an industrial exhibition. Interest in transformers arose only after alternating currents began to find ever wider application, and transformers were rediscovered first by Gaulard and Gibbs, and then by Zipernowsky and others. The question of priority in the invention arose, and then Yablochkov’s inventions and patents were recalled. The existence of these patents enabled the court to decide the dispute between these two groups of inventors, rejecting both and recognizing priority for Yablochkov. Subsequently this priority was also recognized by most electrical engineers in Germany, France, England, and the USA. In Russia the invention of the transformer was sometimes attributed to Usagin, a co-worker of Stoletov at Moscow University. However, it may now be considered established that Usagin’s proposal was made several years after Yablochkov’s and was an improvement of Yablochkov’s apparatus.

Yablochkov’s transformers, though with considerable delay, were also taken up by the French firm that had held Yablochkov’s patents since 1876. The company issued special sheets with illustrations of the transformers it was producing, in which it was written: “The Company must correct a grave error made earlier: namely, among the numerous patents which it owns, there is one little known, but of definite importance concerning all patents that do not concern transformers; this is Yablochkov’s patent of 1876 and 1877, in which both the principle of operation and the method of application of transformers are described. Yablochkov’s priority in this matter has recently been recognized in England as well.”

Thus the priority of Yablochkov in the invention of the alternating-current transformer may be regarded as established. The priority of another Russian inventor, M. O. Dolivo-Dobrovolsky, in the invention of the three-phase-current transformer with three cores should likewise be considered established. To him also belongs the idea and the constructive development of an instrument for measuring, by the wattmeter method, losses due to Foucault currents and hysteresis in sheet steel intended for the manufacture of transformer cores. Another Russian scientist, A. G. Stoletov, devised a method for the most accurate measurement of the magnetic permeability of materials, rediscovered two years later by Rowland. The possibility of simply measuring losses and magnetic permeability made it possible substantially to improve the quality of the sheet steel used for manufacturing transformer cores, and thereby to improve the quality of transformers.

The invention of transformers marked the beginning of a new era in the history of electrical engineering. Only the existence of transformers and the use of three-phase current made it possible for the idea of electrification to develop so widely and to become the basis for the development of the modern national economy. For this reason, the speaker concluded, the names of P. N. Yablochkov and M. A. Dolivo-Dobrovolsky must be placed alongside the names of the greatest inventors of the world.

M. Radovsky