A transformer is an electrical device that transfers alternating-current energy or signals between circuits through electromagnetic induction.
The transformer was invented to meet the need to use electricity and transmit power over long distances. Its birth and gradual perfection took a very long time.
In 1831, Michael Faraday discovered that an electric current produces a magnetic field and vice versa – and that a changing magnetic field also produces electricity.
In 1880, Thomas Edison patented a power distribution system, which played a key role in bringing electric lighting into use. By 1887, 121 Edison power stations in the United States supplied direct current to customers. The problem was that direct current could only reach customers within a radius of about 2.4km from a station. Electrifying the whole country would have required a huge number of Edison stations at enormous cost – so a way was needed to transmit power over long distances without building so many stations.
From this need, in 1884, the first transformer was invented by a group of engineers – Károly Zipernowsky, Miksa Déri and Ottó Titusz Bláthy. They designed transformers for both experimental and commercial systems, known as the “ZBD transformer”.
Ottó Bláthy (1860–1939), Miksa Déri (1854–1938), Károly Zipernowsky (1853–1942)
The “ZBD transformer”
Later, Lucien Gaulard, Sebastian Ferranti and William Stanley refined the design and produced later generations of transformers. William Stanley’s first transformer was built in 1885 for single-phase alternating current.
William Stanley (1858–1916), Lucien Gaulard (1850–1888) and Sebastian Ferranti (1864–1930)
Transformer of 1885
In 1886, Stanley’s first transformer was put into service for electric lighting in Great Barrington, Massachusetts, USA.
Transformer of 1886
In 1889, Russian-born engineer Mikhail Dolivo-Dobrovolsky developed the first three-phase transformer at AEG in Germany, a year after developing the first three-phase generator. Dolivo-Dobrovolsky used his transformer in the first complete AC power system (generator + transformer + line + transformer + motor and lamps) in 1891.
In 1891, the Tesla coil was built by Nikola Tesla, able to produce alternating current at high frequency and high voltage.
Three-phase transformer (round-core type), 1891
Since the 1880s, transformers have been continuously improved – becoming more efficient, more compact and more powerful.
Air-cooled transformer built by William Stanley in 1895 for a three-phase AC power station
Large Westinghouse transformer from 1917 at the Folsom hydropower plant, California
Inchicore substation, 1930
1200kV transformer – India (2011)
800kV transformer (2014)
The world’s largest transformer in 2017
