Editing Transformer (section)

===First alternating current transformers===
By the 1870s, efficient [[Electric generator|generators]] producing [[alternating current|alternating current (AC)]] were available, and it was found AC could power an induction coil directly, without an [[interrupter]].

In 1876, Russian engineer [[Pavel Yablochkov]] invented a lighting system based on a set of induction coils where the primary windings were connected to a source of AC. The secondary windings could be connected to several [[Yablochkov candle|'electric candles']] (arc lamps) of his own design. The coils Yablochkov employed functioned essentially as transformers.<ref name=maglab>{{Cite web|url=https://nationalmaglab.org/education/magnet-academy/history-of-electricity-magnetism/museum/stanley-transformer|title=Stanley Transformer – 1886 - MagLab|access-date=2021-07-27|archive-date=2017-10-11|archive-url=https://web.archive.org/web/20171011232657/https://nationalmaglab.org/education/magnet-academy/history-of-electricity-magnetism/museum/stanley-transformer|url-status=dead}}</ref>

In 1878, the [[Ganz Works|Ganz factory]], Budapest, Hungary, began producing equipment for electric lighting and, by 1883, had installed over fifty systems in Austria-Hungary. Their AC systems used arc and incandescent lamps, generators, and other equipment.<ref name="Guarnieri2013-56"/><ref name=Hughes1993-95>{{harvnb|Hughes|1993|pp=95–96}}</ref>

In 1882, [[Lucien Gaulard]] and [[John Dixon Gibbs]] first exhibited a device with an initially widely criticized laminated plate open iron core called a 'secondary generator' in London, then sold the idea to the [[Westinghouse Electric Corporation|Westinghouse]] company in the United States in 1886.<ref name="allan">{{Cite journal | last = Allan | first=D.J.| title = Power Transformers – The Second Century | journal = Power Engineering Journal|date=Jan 1991|volume=5|issue=1|pages=5–14 | doi = 10.1049/pe:19910004| doi-broken-date=7 December 2024}}</ref> They also exhibited the invention in Turin, Italy in 1884, where it was highly successful and adopted for an electric lighting system.<ref name=Uppenborn1889>{{cite book|url=https://archive.org/details/historyoftransfo00upperich|last=Uppenborn|first=F. J.|title=History of the Transformer|publisher=E. & F. N. Spon|location=London|year=1889|pages=[https://archive.org/details/historyoftransfo00upperich/page/35 35]–41}}</ref> Their open-core device used a fixed 1:1 ratio to supply a series circuit for the utilization load (lamps). However, the voltage of their system was controlled by moving the iron core in or out.<ref>{{cite journal |last1=Halacsy |first1=Andrew |last2=Fuchs |first2=George |date=April 1961 |title= Transformer Invented 75 Years Ago|url=https://ieeexplore.ieee.org/document/4500994 |journal=  Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems|volume=80 |issue=3 |pages=121–125 |doi=10.1109/AIEEPAS.1961.4500994 |s2cid=51632693 |access-date=November 28, 2023 |archive-date=November 28, 2023 |archive-url=https://web.archive.org/web/20231128081004/https://ieeexplore.ieee.org/document/4500994 |url-status=bot: unknown }}</ref>

====Early series circuit transformer distribution====
Induction coils with open magnetic circuits are inefficient at transferring power to [[Electrical load|loads]]. Until about 1880, the paradigm for AC power transmission from a high voltage supply to a low voltage load was a series circuit. Open-core transformers with a ratio near 1:1 were connected with their primaries in series to allow use of a high voltage for transmission while presenting a low voltage to the lamps. The inherent flaw in this method was that turning off a single lamp (or other electric device) affected the voltage supplied to all others on the same circuit. Many adjustable transformer designs were introduced to compensate for this problematic characteristic of the series circuit, including those employing methods of adjusting the core or bypassing the magnetic flux around part of a coil.<ref name=Uppenborn1889/>
Efficient, practical transformer designs did not appear until the 1880s, but within a decade, the transformer would be instrumental in the [[war of the currents]], and in seeing AC distribution systems triumph over their DC counterparts, a position in which they have remained dominant ever since.<ref name="Coltman1988">{{harvnb|Coltman|1988|pp=86–95}}</ref>

[[Image:Trafo1885.jpg|thumb|right|Shell form transformer. Sketch used by Uppenborn to describe ZBD engineers' 1885 patents and earliest articles.<ref name=Uppenborn1889/>]]

[[Image:DBZ trafo.jpg|thumb|right|Core form, front; shell form, back. Earliest specimens of ZBD-designed high-efficiency constant-potential transformers manufactured at the Ganz factory in 1885.]]
[[Image:ZBD team.jpg|right|thumb|The ZBD team consisted of [[Károly Zipernowsky]], [[Ottó Bláthy]] and [[Miksa Déri]]]]
[[Image:StanleyTransformer.png|thumb|right|Stanley's 1886 design for adjustable gap open-core induction coils]]