It is generally accepted that electric traction originated around 1880, when Werner von Siemens first presented a machine powered by an electric motor at the Berlin World's Fair. By the dawn of the twentieth century, all types of electric motor were known, whether direct current, synchronous or asynchronous. What these machines lacked, however, was the flexibility of adjustment, which power electronics was to provide when it made its debut with thyristors at the end of the 1960s.
The foundation of power electronics is essentially based on the concept of the static switch, made possible by silicon, a material with astonishing properties, capable of transforming from an insulator to a conductor by means of a simple electrical command.
By exploring the field of electric traction from its origins through all the technological stages up to the advent of electronic switches, we can appreciate the inventive genius of railway engineers and measure the gradual but constant increase in the performance and compactness of traction equipment with each evolution of power semiconductors, diodes, thyristors, GTOs and IGBTs.