Editing Transformer (section)

===Closed-core transformers and parallel power distribution===
In the autumn of 1884, [[Károly Zipernowsky]], [[Ottó Bláthy]] and [[Miksa Déri]] (ZBD), three Hungarian engineers associated with the [[Ganz Works]], had determined that open-core devices were impracticable, as they were incapable of reliably regulating voltage.<ref name=Hughes1993-95/> The Ganz factory had also in the autumn of 1884 made delivery of the world's first five high-efficiency AC transformers, the first of these units having been shipped on September 16, 1884.<ref name="Halacsy1961">{{harvnb|Halacsy|Von Fuchs|1961|pp=121–125}}</ref> This first unit had been manufactured to the following specifications: 1,400 W, 40&nbsp;Hz, 120:72 V, 11.6:19.4 A, ratio 1.67:1, one-phase, shell form.<ref name="Halacsy1961"/> In their joint 1885 patent applications for novel transformers (later called ZBD transformers), they described two designs with closed magnetic circuits where copper windings were either wound around an iron wire ring core or surrounded by an iron wire core.<ref name=Uppenborn1889/> The two designs were the first application of the two basic transformer constructions in common use to this day, termed "core form" or "shell form" .<ref name="Lucas (2000)">{{cite web|last=Lucas|first=J.R.|title=Historical Development of the Transformer|url=http://www.elect.mrt.ac.lk/Transformer_history_2000.pdf|publisher=IEE Sri Lanka Centre|access-date=Mar 1, 2012}}</ref>

In both designs, the magnetic flux linking the primary and secondary windings traveled almost entirely within the confines of the iron core, with no intentional path through air (see [[#Toroidal cores|Toroidal cores]] below). The new transformers were 3.4 times more efficient than the open-core bipolar devices of Gaulard and Gibbs.<ref name=Jeszenszky>{{cite web|last=Jeszenszky|first=Sándor|title=Electrostatics and Electrodynamics at Pest University in the Mid-19th Century|url=http://ppp.unipv.it/Collana/Pages/Libri/Saggi/Volta%20and%20the%20History%20of%20Electricity/V%26H%20Sect2/V%26H%20175-182.pdf|publisher=[[University of Pavia]]|access-date=Mar 3, 2012|archive-date=June 27, 2022|archive-url=https://web.archive.org/web/20220627060208/http://ppp.unipv.it/Collana/Pages/Libri/Saggi/Volta%20and%20the%20History%20of%20Electricity/V%26H%20Sect2/V%26H%20175-182.pdf|url-status=bot: unknown}}</ref> The ZBD patents included two other major interrelated innovations: one concerning the use of parallel connected, instead of series connected, utilization loads, the other concerning the ability to have high turns ratio transformers such that the supply network voltage could be much higher (initially 1,400 to 2,000 V) than the voltage of utilization loads (100 V initially preferred).<ref name="Ideal (2008)">{{cite web|title=Hungarian Inventors and Their Inventions|url=http://www.institutoideal.org/conteudo_eng.php?&sys=biblioteca_eng&arquivo=1&artigo=94&ano=2008|publisher=Institute for Developing Alternative Energy in Latin America|access-date=Mar 3, 2012|url-status=dead|archive-url=https://web.archive.org/web/20120322223457/http://www.institutoideal.org/conteudo_eng.php?&sys=biblioteca_eng&arquivo=1&artigo=94&ano=2008|archive-date=2012-03-22}}</ref><ref name=BUTE-OMIKK-BlathyOtto>{{cite web|title=Bláthy, Ottó Titusz|url=http://www.omikk.bme.hu/archivum/angol/htm/blathy_o.htm|publisher=Budapest University of Technology and Economics, National Technical Information Centre and Library|access-date=Feb 29, 2012}}</ref> When employed in parallel connected electric distribution systems, closed-core transformers finally made it technically and economically feasible to provide electric power for lighting in homes, businesses and public spaces. Bláthy had suggested the use of closed cores, Zipernowsky had suggested the use of [[Shunt (electrical)|parallel shunt connections]], and Déri had performed the experiments;<ref name="Smil">{{cite book|url=https://archive.org/details/creatingtwentiet0000smil|url-access=registration|quote=ZBD transformer.|last=Smil|first=Vaclav|title=Creating the Twentieth Century: Technical Innovations of 1867–1914 and Their Lasting Impact|location=Oxford |publisher=Oxford University Press|year=2005|page=[https://archive.org/details/creatingtwentiet0000smil/page/71 71]|isbn=978-0-19-803774-3}}</ref> In early 1885, the three engineers also eliminated the problem of [[eddy current]] losses with the invention of the lamination of electromagnetic cores.<ref>{{cite book|author=Electrical Society of Cornell University|title=Proceedings of the Electrical Society of [[Cornell University]]|publisher=Andrus & Church|year=1896|page=39}}</ref>

Transformers today are designed on the principles discovered by the three engineers. They also popularized the word 'transformer' to describe a device for altering the EMF of an electric current<ref>{{cite web|url=http://www.kfki.hu/~aznagy/lecture/lecture.htm|last=Nagy|first=Árpád Zoltán|title=Lecture to Mark the 100th Anniversary of the Discovery of the Electron in 1897 (preliminary text)|location=Budapest|date=Oct 11, 1996|access-date=July 9, 2009|archive-date=November 25, 2012|archive-url=https://web.archive.org/web/20121125115109/http://www.kfki.hu/~aznagy/lecture/lecture.htm|url-status=dead}}</ref> although the term had already been in use by 1882.<ref>{{cite book|title = Oxford English Dictionary|url=https://archive.org/details/oxfordenglishdic0015unse|url-access = registration|edition=2nd|year=1989|publisher=Oxford University Press}}</ref><ref>{{cite book|url=https://archive.org/details/modernapplicati00hospgoog| last=Hospitalier|first=Édouard|year= 1882|title=The Modern Applications of Electricity|translator= Julius Maier|location=New York|publisher=D. Appleton & Co.|page=[https://archive.org/details/modernapplicati00hospgoog/page/n121 103]}}</ref> In 1886, the ZBD engineers designed, and the Ganz factory supplied electrical equipment for, the world's first [[power station]] that used AC generators to power a parallel connected common electrical network, the steam-powered Rome-Cerchi power plant.<ref>{{cite web|url=http://www.iec.ch/cgi-bin/tl_to_htm.pl?section=technology&item=144| title=Ottó Bláthy, Miksa Déri, Károly Zipernowsky| publisher=IEC Techline| access-date=Apr 16, 2010| url-status=dead| archive-url=https://web.archive.org/web/20101206042832/http://www.iec.ch/cgi-bin/tl_to_htm.pl?section=technology&item=144| archive-date=2010-12-06}}</ref>