Transformers

Past and present

1884 was the year of the first presentation of Goulard and Gibbs secondary generator (see figure) at the International Electricity Expo in Turin, Italy, largely applauded by the judges.
This year sees the official birth of the first AC transformer and it is also thanks to Goulard and Gibbs for its present name. Unfortunately, as it happened for many inventors, history did not recognize immediate glory and they died very poor, so let’s remember them every time we use an electrical transformer.
After them other technicians such as Ganz, Stanley, Mordey, the Westinghouse Co., Siemens, De Ferranti and Varley studied and designed various electrical transformers, and in a few years’ time developed structures not much different from today’s model.
After over 120 years from its birth, the interest continues in variable transformer development and manufacturing. What has changed from then to present days?
The basic physics is obviously the same. The major changes concern the material, characteristics and accessories.
From wooden supports to the gum varnish coated cardboard insulation, from soft iron wiring to cut magnetic sheets with very low losses to insulating materials which can operate at 200 °C, without loosing their high dielectric characteristics.
From oily varnish coatings for the copper wiring to the present enamels which can operate at 220 °C; from the use of cellulose paper or gutta-percha to the present insulating material in Mylar, Nomex or Kapton.
In the last 50 years, the demand for transformers has increased, from simple use in feeder systems to electronics (where it must work with curve less wave shape).
The three-phase transformer, thanks to its high quality electric performance, is able to balance always more frequently non-linear electronic and electric systems.
With the wide spread of computers and gaseous discharge lighting systems, the old transformer can help remove from the electric lines the harmonicas that would otherwise travel freely.
During the past years and thanks to a continuous technological improvement, variable transformers are always more frequently used for everyday devices and have become essential for setting regulations.