Editing Alternating current (section)

=== Transformers ===
The development of the alternating current [[transformer]] to change voltage from low to high level and back, allowed generation and consumption at low voltages and transmission, over great distances, at high voltage, with savings in the cost of conductors and energy losses. A bipolar open-core [[Transformer|power transformer]] developed by [[Lucien Gaulard]] and [[John Dixon Gibbs]] was demonstrated in London in 1881, and attracted the interest of [[Westinghouse Electric (1886)|Westinghouse]]. They exhibited an AC system powering arc and incandescent lights was installed along five railway stations for the Metropolitan Railway in [[London]] and a single-phase multiple-user AC distribution system [[Turin]] in 1884.<ref>{{Cite journal |last=Allerhand |first=Adam |date=2019 |title=Early AC Power: The First Long-Distance Lines [History] |url=https://ieeexplore.ieee.org/document/8802330 |journal=IEEE Power and Energy Magazine |volume=17 |issue=5 |pages=82–90 |doi=10.1109/MPE.2019.2921059 |issn=1540-7977|url-access=subscription }}</ref> These early induction coils with open magnetic circuits were inefficient at transferring power to [[Electrical load|loads]].{{fact|date=December 2024}} Until about 1880, the paradigm for AC power transmission from a high voltage supply to a low voltage load was a series circuit.{{fact|date=December 2024}} 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.{{fact|date=December 2024}} 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.{{fact|date=December 2024}} 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="FJU1889" /> The direct current systems did not have these drawbacks, giving it significant advantages over early AC systems.

In the UK, [[Sebastian Ziani de Ferranti|Sebastian de Ferranti]], who had been developing AC generators and transformers in London since 1882, redesigned the AC system at the [[Grosvenor Gallery#Generating station|Grosvenor Gallery power station]] in 1886 for the London Electric Supply Corporation (LESCo) including alternators of his own design and open core transformer designs with serial connections for utilization loads - similar to Gaulard and Gibbs.{{sfnp|Hughes|1993|p=98}} In 1890, he designed [[Deptford Power Station|their power station at Deptford]]<ref>{{cite web|url=http://www.mosi.org.uk/collections/explore-the-collections/ferranti-online/timeline.aspx|title=Ferranti Timeline|archive-url=https://web.archive.org/web/20151003002335/http://www.mosi.org.uk/collections/explore-the-collections/ferranti-online/timeline.aspx|archive-date=2015-10-03| website=Museum of Science and Industry (Manchester)|access-date=February 22, 2012}}</ref> and converted the Grosvenor Gallery station across the Thames into an [[electrical substation]], showing the way to integrate older plants into a universal AC supply system.{{sfnp|Hughes|1993|p=208}}

[[File:ZBD team.jpg|thumb|right|The Hungarian ZBD Team ([[Károly Zipernowsky]], [[Ottó Bláthy]], [[Miksa Déri]]), inventors of the first high efficiency, closed-core shunt connection [[transformer]]]]

[[File:DBZ trafo.jpg|right|thumb|The prototype of the ZBD transformer on display at the Széchenyi István Memorial Exhibition, [[Nagycenk]] in [[Hungary]]]]

In the autumn{{Ambiguous|date=January 2023}} of 1884, [[Károly Zipernowsky]], [[Ottó Bláthy]] and [[Miksa Déri]] (ZBD), three engineers associated with the [[Ganz Works]] of Budapest, determined that open-core devices were impractical, as they were incapable of reliably regulating voltage.{{sfnp|Hughes|1993|p=95}} 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>{{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 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 a ring core of iron wires or else surrounded by a core of iron wires.<ref name="FJU1889" /> 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 [[transformer#Toroidal cores|toroidal cores]]). The new transformers were 3.4 times more efficient than the open-core bipolar devices of Gaulard and Gibbs.<ref>{{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 |archive-url=https://ghostarchive.org/archive/20221009/http://ppp.unipv.it/Collana/Pages/Libri/Saggi/Volta%20and%20the%20History%20of%20Electricity/V%26H%20Sect2/V%26H%20175-182.pdf |archive-date=2022-10-09 |url-status=live |publisher=[[University of Pavia]]|access-date=Mar 3, 2012}}</ref> The Ganz factory in 1884 shipped the world's first five high-efficiency AC transformers.<ref name="Halacsy (1961)" /> 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="Halacsy (1961)" />

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 140 to 2000&nbsp;V) than the voltage of utilization loads (100&nbsp;V initially preferred).<ref>{{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>{{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.<ref>{{cite web |title=Bláthy, Ottó Titusz (1860–1939) |url=http://www.hpo.hu/English/feltalalok/blathy.html |publisher=Hungarian Patent Office |access-date=Jan 29, 2004 |archive-date=December 2, 2010 |archive-url=https://web.archive.org/web/20101202031830/http://www.hpo.hu/English/feltalalok/blathy.html |url-status=dead}}</ref><ref>{{cite web |last=Zipernowsky|first=K.|author2= Déri, M.|author3= Bláthy, O.T. | url=http://www.freepatentsonline.com/0352105.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.freepatentsonline.com/0352105.pdf |archive-date=2022-10-09 |url-status=live|title=Induction Coil|publisher=U.S. Patent 352 105, issued Nov. 2, 1886|access-date=July 8, 2009}}</ref>
 
The other essential milestone was the introduction of 'voltage source, voltage intensive' (VSVI) systems'<ref>American Society for Engineering Education. Conference – 1995: Annual Conference Proceedings, Volume 2, (PAGE: 1848)</ref> by the invention of constant voltage generators in 1885.{{sfnp|Hughes|1993|p=96}} 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> Ottó Bláthy also invented the first AC [[electricity meter]].<ref>{{cite web |author=Eugenii Katz |url=http://people.clarkson.edu/~ekatz/scientists/blathy.html |title=Blathy |publisher=People.clarkson.edu |access-date=2009-08-04| archive-url = https://web.archive.org/web/20080625015707/http://people.clarkson.edu/~ekatz/scientists/blathy.html| archive-date = June 25, 2008}}</ref><ref>{{cite journal |last=Ricks |first=G.W.D. |title=Electricity Supply Meters |journal=Journal of the Institution of Electrical Engineers |date=March 1896 |volume=25 |number=120 |pages=57–77 |doi=10.1049/jiee-1.1896.0005 |url=https://archive.org/stream/journal06sectgoog#page/n77/mode/1up}} Student paper read on January 24, 1896, at the Students' Meeting.</ref><ref>''The Electrician'', Volume 50. 1923</ref><ref>Official gazette of the United States Patent Office: Volume 50. (1890)</ref>