ELECTROTECHNICS. — After the discovery of electromagnetic, electrothermal, and electrochemical phenomena, no one could doubt the possibility of significant practical applications of electric currents, but certainly no one would have dared to imagine that within a century they would reach their present proportions.
Given the impossibility of delving into details, only a brief outline is provided of the salient features of the current state of electrical technology.
I. INDUSTRIAL PRODUCTION OF ELECTRIC CURRENTS
Although surprising and beneficial to the development of electrology, the production of electric currents by means of batteries, even the most advanced, proved too limited, cumbersome, and expensive for widespread use. Therefore, immediately after the discovery of electromagnetic induction phenomena, which allowed for the production of electric currents through an alternative method, the problem of achieving large-scale induction arose. The first devices, still of limited power, consisted of circuits in which lines of force emanating from permanent magnets were alternately connected and disconnected, demonstrating the possibility of a solution to the problem but also revealing its difficulty. The currents that could be produced in this way, besides being too weak, were alternating and could practically only be used to deliver the so-called electric shocks, sometimes for therapeutic purposes but more often as a novel amusement.It was not until 1860 that A. Pacinotti succeeded in constructing the first machine that, further refined, could automatically provide a direct current. Technically, the problem could be considered solved, but it was only about a decade later that the first industrial electric current generator (electric dynamo) was built in France, operating on Pacinotti’s principle.
Today, direct current generators with power outputs of thousands of horsepower and voltages reaching several thousand volts are constructed worldwide according to various designs.
Yet even in this sector of human activity, a curious revolution occurred. Alternating currents (which periodically reverse their direction), which could have been produced in significant quantities even before direct currents and were thought to be of little or no practical use, are now by far the most widely employed, while direct currents—preferred, for example, in railway and tramway traction—are obtained using so-called converters, complex machines that, when supplied with alternating current, produce direct current at usable voltages.
At this point, it is worth noting that the aforementioned processes are only advantageous because the efficiency (i.e., the ratio between input and output) of electromagnetic transformations is exceptionally high compared to other transformations in other fields of physics. Whereas, for example, the efficiency of machines that convert thermal energy into mechanical energy (heat engines) ranges between ten and thirty percent, that of analogous machines converting electrical energy into mechanical energy or vice versa can exceed ninety percent, with the highest figures observed in devices that transform electrical energy from one form to another. Static transformers, in particular, can achieve efficiencies as high as ninety-nine percent.