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Electric power transmission Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines that facilitate this movement form a ''transmission network''. This is d ...
, the tools and means of moving electricity far from where it is generated, date back to the late 19th century. They include the movement of electricity in bulk (formally called "
transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission ** ...
") and the delivery of electricity to individual customers ("
distribution Distribution may refer to: Mathematics * Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations *Probability distribution, the probability of a particular value or value range of a vari ...
"). In the beginning, the two terms were used interchangeably.


Early transmission

Prior to electricity, various systems had been used for transmission of power across large distances. Chief among them were telodynamic (cable in motion), pneumatic (pressurized air), and hydraulic (pressurized fluid) transmission. Cable cars were the most frequent example of telodynamic transmission, whose lines could extend for several miles for a single section. Pneumatic transmission was used for city power transmission systems in Paris, Birmingham, Rixdorf, Offenbach, Dresden and Buenos Aires at the beginning of the twentieth century. Cities in the 19th century also used hydraulic transmission using high pressure water mains to deliver power to factory motors. London's system delivered over a network of pipes carrying water at . These systems were replaced by cheaper and more versatile electrical systems, but by the end of the 19th century, city planners and financiers were well aware of the benefits, economics, and process of establishing power transmission systems. In the early days of electric power usage, widespread transmission of electric power had two obstacles. First, devices requiring different voltages required specialized generators with their own separate lines. Street lights, electric motors in factories, power for streetcars and lights in homes are examples of the diversity of devices with voltages requiring separate systems. Secondly, generators had to be relatively near their loads (a mile or less for low voltage devices). It was known that longer distance transmission was possible the higher the voltage was raised, so both problems could be solved if transforming voltages from a single universal power line could be done efficiently.


Specialized systems

Much of early electricity was
direct current Direct current (DC) is one-directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or ev ...
, which could not easily be increased or decreased in voltage either for long-distance transmission or for sharing a common line to be used with multiple types of electric devices. Companies simply ran different lines for the different classes of loads their inventions required. For example, Charles Brush's New York
arc lamp An arc lamp or arc light is a lamp that produces light by an electric arc (also called a voltaic arc). The carbon arc light, which consists of an arc between carbon electrodes in air, invented by Humphry Davy in the first decade of the 1800s, ...
systems required up to 10 kV for many lamps in a series circuit, Edison's
incandescent light An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxidat ...
s used 110 V,
streetcars A tram (called a streetcar or trolley in North America) is a rail vehicle that travels on tramway tracks on public urban streets; some include segments on segregated right-of-way. The tramlines or networks operated as public transport ar ...
built by
Siemens Siemens AG ( ) is a German multinational conglomerate corporation and the largest industrial manufacturing company in Europe headquartered in Munich with branch offices abroad. The principal divisions of the corporation are ''Industry'', ''E ...
or Sprague required large motors in the 500 volt range, whereas industrial motors in factories used still other voltages. Due to this specialization of lines, and because transmission was so inefficient, it seemed at the time that the industry would develop into what is now known as a
distributed generation Distributed generation, also distributed energy, on-site generation (OSG), or district/decentralized energy, is electrical generation and storage performed by a variety of small, grid-connected or distribution system-connected devices referred to ...
system with large numbers of small generators located near their loads.


Early high voltage exterior lighting

High voltage was of interest to early researchers working on the problem of transmission over distance. They knew from elementary electricity principle that the same amount of power could be transferred on a cable by doubling the voltage and halving the current. Due to Joule's Law, they also knew that the power lost from heat in a wire is proportional to the square of the current traveling on it, regardless the voltage, and so by doubling the voltage, the same cable would be capable of transmitting the same amount of power four times the distance. At the
Paris Exposition of 1878 The third Paris World's Fair, called an Exposition Universelle in French, was held from 1 May to 10 November 1878. It celebrated the recovery of France after the 1870–71 Franco-Prussian War. Construction The buildings and the fairgr ...
, electric arc lighting had been installed along the Avenue de l'Opera and the Place de l'Opera, using electric Yablochkov arc lamps, powered by
Zénobe Gramme Zénobe Théophile Gramme (4 April 1826 – 20 January 1901) was a Belgian electrical engineer. He was born at Jehay-Bodegnée on 4 April 1826, the sixth child of Mathieu-Joseph Gramme, and died at Bois-Colombes on 20 January 1901. He invented ...
alternating current dynamos. Yablochkov candles required high voltage, and it was not long before experimenters reported that the arc lamps could be powered on a circuit. Within a decade scores of cities would have lighting systems using a central power plant that provided electricity to multiple customers via electrical transmission lines. These systems were in direct competition with the dominant gaslight utilities of the period. The idea of investing in a central plant and a network to deliver energy produced to customers who pay a recurring fee for service was familiar business model for investors: it was identical to the lucrative gaslight business, or the hydraulic and pneumatic power transmission systems. The only difference was the commodity being delivered was electricity, not gas, and the "pipes" used for delivering were more flexible. The California Electric Company (now PG&E) in San Francisco in 1879 used two direct current generators from Charles Brush's company to supply multiple customers with power for their arc lamps. This San Francisco system was the first case of a
utility As a topic of economics, utility is used to model worth or value. Its usage has evolved significantly over time. The term was introduced initially as a measure of pleasure or happiness as part of the theory of utilitarianism by moral philosophe ...
selling electricity from a central plant to multiple customers via
transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission ** ...
lines. CEC soon opened a second plant with 4 additional generators. Service charges for light from sundown to midnight was $10 per lamp per week. Grand Rapids Electric Light & Power Company, established in March 1880 by
William T. Powers William T. Powers (August 29, 1926 – May 24, 2013) was a medical physicist and an independent scholar of experimental and theoretical psychology who developed the perceptual control theory (PCT) model of behavior as the control of perception. He ...
and others, began operation of the world's first commercial central station hydroelectric power plant, Saturday, July 24, 1880, getting power from Wolverine Chair and Furniture Company's water turbine. It operated a 16-light Brush electric dynamo lighting several storefronts in Grand Rapids, Michigan. It is the earliest predecessor of Consumers Energy of Jackson, Michigan. In December 1880, Brush Electric Company set up a central station to supply a length of Broadway with arc lighting. By the end of 1881, New York, Boston, Philadelphia, Baltimore, Montreal, Buffalo, San Francisco, Cleveland and other cities had Brush arc lamp systems, producing public light well into the 20th century. By 1893 there were 1500 arc lamps illuminating New York streets.


Direct current lighting

Early arc lights were extremely bright and the high voltages presented a sparking/fire hazard, making them too dangerous to use indoors. In 1878 inventor
Thomas Edison Thomas Alva Edison (February 11, 1847October 18, 1931) was an American inventor and businessman. He developed many devices in fields such as electric power generation, mass communication, sound recording, and motion pictures. These inventi ...
saw a market for a system that could bring electric lighting directly into a customer's business or home, a niche not served by arc lighting systems. After devising a commercially viable
incandescent light bulb An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxi ...
in 1879, Edison went on to develop the first large scale investor-owned electric illumination "
utility As a topic of economics, utility is used to model worth or value. Its usage has evolved significantly over time. The term was introduced initially as a measure of pleasure or happiness as part of the theory of utilitarianism by moral philosophe ...
" in lower Manhattan, eventually serving one square mile with 6 "jumbo dynamos" housed at
Pearl Street Station Pearl Street Station was the first commercial central power plant in the United States. It was located at 255–257 Pearl Street in the Financial District of Manhattan, New York City, just south of Fulton Street on a site measuring . The statio ...
. When service began in September 1882, there were 85 customers with 400 light bulbs. Each dynamo produced 100 kWenough for 1200 incandescent lights, and transmission was at 110 V via underground conduits. The system cost $300,000 to build with installation of the of underground conduits one of the most expensive parts of the project. Operating expenses exceeded income in the first two years and fire destroyed the plant in 1890. Further, Edison had a three wire system so that either 110 V or 220 V could be supplied to power some motors.


Availability of large-scale generation

Availability of large amounts of power from diverse locations would become possible after Charles Parsons' production of
turbogenerator A turbo generator is an electric generator connected to the shaft of a steam turbine or gas turbine for the generation of electric power. Large steam-powered turbo generators provide the majority of the world's electricity and are also used b ...
s beginning 1889. Turbogenerator output quickly jumped from 100 kW to 25 megawatts in two decades. Prior to efficient turbogenerators, hydroelectric projects were a significant source of large amounts of power requiring transmission infrastructure.


Transformers and alternating current

When
George Westinghouse George Westinghouse Jr. (October 6, 1846 – March 12, 1914) was an American entrepreneur and engineer based in Pennsylvania who created the railway air brake and was a pioneer of the electrical industry, receiving his first patent at the age ...
became interested in electricity, he quickly and correctly concluded that Edison's low voltages were too inefficient to be scaled up for transmission needed for large systems. He further understood that long-distance transmission needed high voltage and that inexpensive conversion technology only existed for alternating current. Transformers would play the decisive role in the victory of alternating current over direct current for transmission and distribution systems. In 1876, Pavel Yablochkov patented his mechanism of using induction coils to serve as a step up transformer prior to the Paris Exposition demonstrating his arc lamps. In 1881,
Lucien Gaulard Lucien Gaulard (16 July 1850 – 26 November 1888) invented devices for the transmission of alternating current electrical energy. Biography Gaulard was born in Paris, France in 1850. A power transformer developed by Gaulard of France and Joh ...
and
John Dixon Gibbs John Dixon Gibbs (1834–1912) was a British engineer and financier who, together with Lucien Gaulard, is often credited as the co-inventor of the AC step-down transformer. The transformer was first demonstrated in 1883 at London's Royal Aquarium ...
developed a more efficient device which they dubbed the secondary generator, namely an early step down transformer whose ratio could be adjusted by configuring the connections between a series of wired bobbins around a spindle, from which an iron core could be added or removed as necessary to vary the power output. The device was subject to various critisims and was occasionally misunderstood as only providing a 1:1 turn ratio. The first demonstrative long-distance (34 km, 21 mi) AC line was built for the 1884 International Exhibition of
Turin, Italy Turin ( , Piedmontese: ; it, Torino ) is a city and an important business and cultural centre in Northern Italy. It is the capital city of Piedmont and of the Metropolitan City of Turin, and was the first Italian capital from 1861 to 1865. The ...
. It was powered by a 2-kV, 130-Hz Siemens & Halske alternator and featured several Gaulard secondary generators with their primary windings connected in series, which fed incandescent lamps. The system proved the feasibility of AC electric power transmission over long distances. Between 1884 and 1885, Hungarian engineers Zipernowsky, Bláthy, and Déri from the
Ganz company The Ganz Works or Ganz ( or , ''Ganz companies'', formerly ''Ganz and Partner Iron Mill and Machine Factory'') was a group of companies operating between 1845 and 1949 in Budapest, Hungary. It was named after Ábrahám Ganz, the founder and the ...
in
Budapest Budapest (, ; ) is the capital and most populous city of Hungary. It is the ninth-largest city in the European Union by population within city limits and the second-largest city on the Danube river; the city has an estimated population o ...
created the efficient "Z.B.D." closed-core coils, as well as the modern electric distribution system. The three had discovered that all former coreless or open-core devices were incapable of regulating voltage, and were therefore impractical. Their joint patent described two versions of a design with no poles: the " closed-core transformer" and the "shell-core transformer". Ottó Bláthy suggested the use of closed-cores, Károly Zipernowsky the use of shunt connections, and Miksa Déri performed the experiments. Smil, Vaclav, ''Creating the Twentieth Century: Technical Innovations of 1867–1914 and Their Lasting Impact''
Oxford University Press, 2005, p. 71.
The new ZBD transformers were 3.4 times more efficient than the open-core bipolar devices of Gaulard and Gibbs. In the closed-core transformer the iron core is a closed ring around which the two coils are wound. In the shell type transformer, the windings are passed through the core. In both designs, the magnetic flux linking the primary and secondary windings travels almost entirely within the iron core, with no intentional path through air. The core consists of iron strands or sheets. These revolutionary design elements would finally make it technically and economically feasible to provide electric power for lighting in homes, businesses and public spaces.
Hungarian Patent Office.
Zipernowsky, Bláthy and Déri also discovered the transformer formula, Vs/Vp = Ns/Np. Electrical and electronic systems the world over rely on the principles of the original
Ganz The Ganz Works or Ganz ( or , ''Ganz companies'', formerly ''Ganz and Partner Iron Mill and Machine Factory'') was a group of companies operating between 1845 and 1949 in Budapest, Hungary. It was named after Ábrahám Ganz, the founder and t ...
transformers. The inventors are also credited with the first use of the word "transformer" to describe a device for altering the EMF of an electric current. A very first operative AC line was put into service in 1885 in via dei Cerchi,
Rome, Italy , established_title = Founded , established_date = 753 BC , founder = King Romulus ( legendary) , image_map = Map of comune of Rome (metropolitan city of Capital Rome, region Lazio, Italy).svg , map_caption ...
, for public lighting. It was powered by two Siemens & Halske alternators rated 30 hp (22 kW), 2 kV at 120 Hz and used 200 series-connected Gaulard 2-kV/20-V step-down transformers provided with a closed magnetic circuit, one for each lamp. Few months later it was followed by the first British AC system, which was put into service at the
Grosvenor Gallery The Grosvenor Gallery was an art gallery in London founded in 1877 by Sir Coutts Lindsay and his wife Blanche. Its first directors were J. Comyns Carr and Charles Hallé. The gallery proved crucial to the Aesthetic Movement because it provide ...
, London. It also featured Siemens alternators and 2.4-kV/100-V step-down transformers, one per user, with shunt-connected primaries. The concept that is the basis of modern transmission using inexpensive step up and step down transformers was first implemented by Westinghouse, William Stanley, Jr. and Franklin Leonard Pope in 1886 in
Great Barrington, Massachusetts Great Barrington is a town in Berkshire County, Massachusetts, United States. It is part of the Pittsfield, Massachusetts, Metropolitan Statistical Area. The population was 7,172 at the 2020 census. Both a summer resort and home to Ski Butternut, ...
, resorting also to European technology. In 1888 Westinghouse also licensed
Nikola Tesla Nikola Tesla ( ; ,"Tesla"
''Random House Webster's Unabridged Dictionary''.
; 1856 – 7 January 1943 ...
's
induction motor An induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor ...
which they would eventually develop into a usable (2-phase) AC motor. The modern 3-phase system was developed by
Mikhail Dolivo-Dobrovolsky Mikhail Osipovich Dolivo-Dobrovolsky (russian: Михаи́л О́сипович Доли́во-Доброво́льский; german: Michail von Dolivo-Dobrowolsky or ''Michail Ossipowitsch Doliwo-Dobrowolski''; – ) was a Russian Empire ...
and
Allgemeine Elektricitäts-Gesellschaft Allgemeine Elektricitäts-Gesellschaft AG (AEG; ) was a German producer of electrical equipment founded in Berlin as the ''Deutsche Edison-Gesellschaft für angewandte Elektricität'' in 1883 by Emil Rathenau. During the Second World War, AE ...
and
Charles Eugene Lancelot Brown Brown c. 1900 Charles Eugene Lancelot Brown (17 June 1863 – 2 May 1924) was a Swiss businessman and engineer who co-founded Brown, Boveri & Cie (BBC), which later became ASEA Brown Boveri. Biography Brown was born on 17 June 1863 in Winterth ...
in Europe, starting in 1889. The International Electro-Technical Exhibition of 1891, in
Frankfurt Frankfurt, officially Frankfurt am Main (; Hessian: , " Frank ford on the Main"), is the most populous city in the German state of Hesse. Its 791,000 inhabitants as of 2022 make it the fifth-most populous city in Germany. Located on it ...
,
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...
, featured the long-distance transmission of high-power, three-phase electric current. It was held between 16 May and 19 October on the disused site of the three former “Westbahnhöfe” (Western Railway Stations) in
Frankfurt am Main Frankfurt, officially Frankfurt am Main (; Hessian: , " Frank ford on the Main"), is the most populous city in the German state of Hesse. Its 791,000 inhabitants as of 2022 make it the fifth-most populous city in Germany. Located on it ...
. The exhibition featured the first long-distance transmission of high-power, three-phase electric current, which was generated 175 km away at Lauffen am Neckar. It successfully operated motors and lights at the fair. When the exhibition closed, the
power station A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid. Many ...
at Lauffen continued in operation, providing electricity for the administrative capital, Heilbronn, making it the first place to be equipped with three-phase AC power. Many corporate technical representatives (including E.W. Rice of Thomson-Houston Electric Company (what became General Electric)) attended. The technical advisers and representatives were impressed. As a result of the successful field trial, three-phase current, as far as Germany was concerned, became the most economical means of transmitting electrical energy. The simplicity of polyphase generators and motors meant that besides their efficiency they could be manufactured cheaply, compactly and would require little attention to maintain. Simple economics would drive the expensive, bulky and mechanically complex DC dynamos to their ultimate extinction. As it turned out, the deciding factor in the
war of the currents The war of the currents was a series of events surrounding the introduction of competing electric power transmission systems in the late 1880s and early 1890s. It grew out of two lighting systems developed in the late 1870s and early 1880s; arc ...
was the availability of low cost step up and step down transformers that meant that all customers regardless of their specialized voltage requirements could be served at minimal cost of conversion. This "universal system" is today regarded as one of the most influential innovations for the use of electricity.


High voltage direct current transmission

The case for alternating current was not clear at the turn of the century and high voltage direct current transmission systems were successfully installed without the benefit of transformers. Rene Thury, who had spent six months at Edison's Menlo Park facility, understood his problem with transmission and was convinced that moving electricity over great distances was possible using direct current. He was familiar with the work of Marcel Deprez, who did early work on high voltage transmission after being inspired by the capability of arc lamp generators to support lights over great distances. Deprez avoided transformers by placing generators and loads in series as
arc lamp An arc lamp or arc light is a lamp that produces light by an electric arc (also called a voltaic arc). The carbon arc light, which consists of an arc between carbon electrodes in air, invented by Humphry Davy in the first decade of the 1800s, ...
systems of Charles F. Brush did. Thury developed this idea into the first commercial system for high-voltage DC transmission. Like Brush's dynamos, current is kept constant, and when increasing load demands more pressure, voltage is increased. The
Thury System Thury may refer to: People *Pierre de Thury ( -1410), said the cardinal Maillezais, a French cardinal of the Avignon Obedience, see Council of Pisa The Council of Pisa was a controversial ecumenical council of the Catholic Church held in 140 ...
was successfully used on several DC transmission projects from Hydro generators. The first in 1885 was a low voltage system in Bözingen, and the first high voltage system went into service in 1889 in
Genoa Genoa ( ; it, Genova ; lij, Zêna ). is the capital of the Italian region of Liguria and the sixth-largest city in Italy. In 2015, 594,733 people lived within the city's administrative limits. As of the 2011 Italian census, the Province of ...
,
Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
, by the ''Acquedotto de Ferrari-Galliera'' company. This system transmitted 630 kW at 14 kV DC over a circuit 120 km long. The largest Thury System was the Lyon Moutiers project that was 230 km in length, eventually delivering 20 megawatts, at 125 kV.


Victory for AC

Ultimately, the versatility of the Thury system was hampered by the fragility of series distribution, and the lack of a reliable DC conversion technology that would not show up until the 1940s with improvements in
mercury arc valve A mercury-arc valve or mercury-vapor rectifier or (UK) mercury-arc rectifier is a type of electrical rectifier used for converting high-voltage or high-current alternating current (AC) into direct current (DC). It is a type of cold cathode gas-fil ...
s. The AC "universal system" won by force of numbers, proliferating systems with transformers both to couple generators to high-voltage transmission lines, and to connect transmission to local distribution circuits. By a suitable choice of
utility frequency The utility frequency, (power) line frequency (American English) or mains frequency (British English) is the nominal frequency of the oscillations of alternating current (AC) in a wide area synchronous grid transmitted from a power station to ...
, both lighting and motor loads could be served. Rotary converters and later mercury-arc valves and other rectifier equipment allowed DC load to be served by local conversion where needed. Even generating stations and loads using different frequencies could also be interconnected using rotary converters. By using common generating plants for every type of load, important
economies of scale In microeconomics, economies of scale are the cost advantages that enterprises obtain due to their scale of operation, and are typically measured by the amount of output produced per unit of time. A decrease in cost per unit of output enables ...
were achieved, lower overall capital investment was required, load factor on each plant was increased allowing for higher efficiency, allowing for a lower cost of energy to the consumer and increased overall use of electric power. By allowing multiple generating plants to be interconnected over a wide area, electricity production cost was reduced. The most efficient available plants could be used to supply the varying loads during the day. Reliability was improved and capital investment cost was reduced, since stand-by generating capacity could be shared over many more customers and a wider geographic area. Remote and low-cost sources of energy, such as
hydroelectric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined an ...
power or mine-mouth coal, could be exploited to lower energy production cost. The first transmission of three-phase alternating current using high voltage took place in 1891 during the international electricity exhibition in
Frankfurt Frankfurt, officially Frankfurt am Main (; Hessian: , " Frank ford on the Main"), is the most populous city in the German state of Hesse. Its 791,000 inhabitants as of 2022 make it the fifth-most populous city in Germany. Located on it ...
. A 15 kV transmission line connected Lauffen on the
Neckar The Neckar () is a river in Germany, mainly flowing through the southwestern state of Baden-Württemberg, with a short section through Hesse. The Neckar is a major right tributary of the Rhine. Rising in the Schwarzwald-Baar-Kreis near Schwen ...
and Frankfurt am Main, apart.


Willamette Falls to Niagara Falls

In 1882, the German
Miesbach–Munich Power Transmission Miesbach–Munich Power Transmission of 1882 was the first Note the voltage of 1,400 V transmission of direct current (DC) electrical energy over a large distance (57 km). After the first International Exposition of Electricity was held in Paris ...
used 2kV DC over . In 1889, the first long-distance transmission of DC electricity in the United States was switched on at Willamette Falls Station, in
Oregon City, Oregon ) , image_skyline = McLoughlin House.jpg , imagesize = , image_caption = The McLoughlin House, est. 1845 , image_flag = , image_seal = Oregon City seal.png , image_map ...
. In 1890, a flood destroyed the power station. This unfortunate event paved the way for the first long-distance transmission of AC electricity in the world when Willamette Falls Electric company installed experimental AC generators from Westinghouse in 1890. That same year, the Niagara Falls Power Company (NFPC) and its subsidiary Cataract Company formed the International Niagara Commission composed of experts, to analyze proposals to harness
Niagara Falls Niagara Falls () is a group of three waterfalls at the southern end of Niagara Gorge, spanning the Canada–United States border, border between the Provinces and territories of Canada, province of Ontario in Canada and the U.S. state, state ...
to generate electricity. The commission was led by
Sir William Thomson William Thomson, 1st Baron Kelvin, (26 June 182417 December 1907) was a British mathematician, mathematical physicist and engineer born in Belfast. Professor of Natural Philosophy at the University of Glasgow for 53 years, he did importan ...
(later Lord Kelvin) and included Eleuthère Mascart from France,
William Unwin William Cawthorne Unwin FRS (12 December 1838 – 17 March 1933)''Evening Standard Obituary'' 18 March 1933. was a British civil and mechanical engineer. He is noted for his extensive work on hydraulics and engines as well as his close a ...
from England, Coleman Sellers from the US, and
Théodore Turrettini Théodore Turrettini (1845–1916) was a Swiss engineer and politician. Life Théodore Turrettini was trained as an engineer at the Polytechnic School of Lausanne, where he graduated in 1867. He then left Switzerland to train in a workshop in ...
from Switzerland. It was backed by
entrepreneur Entrepreneurship is the creation or extraction of economic value. With this definition, entrepreneurship is viewed as change, generally entailing risk beyond what is normally encountered in starting a business, which may include other values t ...
s such as
J. P. Morgan John Pierpont Morgan Sr. (April 17, 1837 – March 31, 1913) was an American financier and investment banker who dominated corporate finance on Wall Street throughout the Gilded Age. As the head of the banking firm that ultimately became known ...
,
Lord Rothschild Baron Rothschild, of Tring in the County of Hertfordshire, is a title in the Peerage of the United Kingdom. It was created in 1885 for Sir Nathan Rothschild, 2nd Baronet, a member of the Rothschild banking family. He was the first Jewish m ...
, and
John Jacob Astor IV John Jacob Astor IV (July 13, 1864 – April 15, 1912) was an American business magnate, real estate developer, investor, writer, lieutenant colonel in the Spanish–American War, and a prominent member of the Astor family. He died in the sink ...
. Among 19 proposals, they even briefly considered
compressed air Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches, an ...
as a
power transmission Power transmission is the movement of energy from its place of generation to a location where it is applied to perform useful work. Power is defined formally as units of energy per unit time. In SI units: :\text = \frac = \frac Since the develo ...
medium, but preferred electricity. They could not decide which method would be best overall. By 1893 the
Niagara Falls Power Company Niagara Falls Hydraulic Power & Manufacturing Company was an American company, based in Niagara Falls, New York that was the first company to generate hydroelectric power from Niagara Falls in 1882. The company built upon several predecessor com ...
had rejected the remaining proposals from a half dozen companies and awarded the generating contract to Westinghouse with further transmission lines and transformer contracts awarded to General Electric. Work began in 1893 on the Niagara Falls generation project: 5,000 horsepower (3,700 kW) was to be generated and transmitted as
alternating current Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in whic ...
, at a frequency of 25 Hz to minimize impedance losses in transmission (changed to 60 Hz in the 1950s). Westinghouse also had to develop a system based on rotary converters to allow them to supply all the needed power standards including single phase and polyphase AC and DC for street cars and factory motors. Westinghouse's initial customer for the power from the
hydroelectric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined an ...
generators at the Edward Dean Adams Station at Niagara in 1895 were the plants of the
Pittsburgh Reduction Company Alcoa Corporation (an acronym for Aluminum Company of America) is a Pittsburgh-based industrial corporation. It is the world's eighth-largest producer of aluminum. Alcoa conducts operations in 10 countries. Alcoa is a major producer of primary ...
which needed large quantities of cheap electricity for
smelting Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a c ...
aluminum. On November 16, 1896, electrical power transmitted to Buffalo began powering its street cars. The generating plants were built by
Westinghouse Electric Corporation The Westinghouse Electric Corporation was an American manufacturing company founded in 1886 by George Westinghouse. It was originally named "Westinghouse Electric & Manufacturing Company" and was renamed "Westinghouse Electric Corporation" in ...
. The scale of the project had General Electric also contributing, building transmission lines and equipment. That same year Westinghouse and General Electric signed a patent sharing agreement, ending some 300 lawsuits the companies were involved in over their competing electrical patents, and giving them monopolistic control over the US electric power industry for years to come. Initially transmission lines were supported by porcelain pin-and-sleeve insulators similar to those used for
telegraphs Telegraphs were an alternative rock band based in Brighton, England. Biography Formed in 2005, Telegraphs was made up of members Darcy Harrison (vocals), Hattie Williams (bass/vocals), Sam Bacon (drums), Darren LeWarne (guitar) and Aung Yay ( ...
and
telephone A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most efficiently the human voice, into e ...
lines. However, these had a practical limit of 40 kV. In 1907, the invention of the disc insulator by Harold W. Buck of the Niagara Falls Power Corporation and Edward M. Hewlett of
General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable ene ...
allowed practical insulators of any length to be constructed for higher voltages.


Early 20th century

Voltages used for electric power transmission increased throughout the 20th century. The first "high voltage" AC power station, rated 4-MW 10-kV 85-Hz, was put into service in 1889 by
Sebastian Ziani de Ferranti Sebastian Pietro Innocenzo Adhemar Ziani de Ferranti (9 April 1864 – 13 January 1930) was a British electrical engineer and inventor. Personal life Sebastian Ziani de Ferranti was born in Liverpool, England. His Italian father, Cesare, was a ...
at
Deptford Deptford is an area on the south bank of the River Thames in southeast London, within the London Borough of Lewisham. It is named after a Ford (crossing), ford of the River Ravensbourne. From the mid 16th century to the late 19th it was home ...
, London. The first electric power transmission line in North America operated at 4000 V. It went online on June 3, 1889, with the lines between the generating station at Willamette Falls in
Oregon City, Oregon ) , image_skyline = McLoughlin House.jpg , imagesize = , image_caption = The McLoughlin House, est. 1845 , image_flag = , image_seal = Oregon City seal.png , image_map ...
, and
Chapman Square ''Chapman Square'' is the debut studio album released by four piece British band Lawson. The album was released on 19 October 2012 via Polydor Records. The album includes their three top ten singles " When She Was Mine", "Taking Over Me" and ...
in downtown
Portland, Oregon Portland (, ) is a port city in the Pacific Northwest and the largest city in the U.S. state of Oregon. Situated at the confluence of the Willamette and Columbia rivers, Portland is the county seat of Multnomah County, the most populous ...
stretching about 13 miles. By 1914 fifty-five transmission systems operating at more than 70,000 V were in service, and the highest voltage then used was 150 kV. The first three-phase alternating current power transmission at 110 kV took place in 1907 between Croton and
Grand Rapids Grand Rapids is a city and county seat of Kent County in the U.S. state of Michigan. At the 2020 census, the city had a population of 198,917 which ranks it as the second most-populated city in the state after Detroit. Grand Rapids is the ...
,
Michigan Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and t ...
. Voltages of 100 kV and more were not established technology until around 5 years later, with for example the first 110 kV line in Europe between Lauchhammer and
Riesa Riesa is a town in the district of Meißen in Saxony, Germany. It is located on the river Elbe, approximately northwest of Dresden. History The name ''Riesa'' is derived from Slavic ''Riezowe''. This name, romanised as "Rezoa", appears first i ...
, Germany, in 1912. In the early 1920s the
Pit River The Pit River is a major river draining from northeastern California into the state's Central Valley. The Pit, the Klamath and the Columbia are the only three rivers in the U.S. that cross the Cascade Range. The longest tributary of the Sacr ...
Cottonwood – Vaca-Dixon line was built for 220 kV transporting power from hydroelectric plants in the
Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primar ...
to the
San Francisco Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area G ...
, at the same time the Big Creek
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lines were upgraded to the same voltage. Both of those systems entered commercial service in 1923. On April 17, 1929 the first 220 kV line in Germany was completed, running from
Brauweiler Brauweiler is a part of Pulheim, west of Cologne, North Rhine-Westphalia in Germany. The former Benedictine , image = Medalla San Benito.PNG , caption = Design on the obverse side of the Saint Benedict Medal , ...
near
Cologne Cologne ( ; german: Köln ; ksh, Kölle ) is the largest city of the German western state of North Rhine-Westphalia (NRW) and the fourth-most populous city of Germany with 1.1 million inhabitants in the city proper and 3.6 millio ...
, over
Kelsterbach Kelsterbach () is a town in Groß-Gerau district in Hessen, Germany and part of the Frankfurt Rhein-Main urban area. It is located on Frankfurt's southwestern outskirts at a bend on the left bank of the river Main, right where a small brook, ca ...
near Frankfurt,
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near
Mannheim Mannheim (; Palatine German: or ), officially the University City of Mannheim (german: Universitätsstadt Mannheim), is the second-largest city in the German state of Baden-Württemberg after the state capital of Stuttgart, and Germany's ...
, Ludwigsburg–Hoheneck near
Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
. This line comprises the North-South interconnect, at the time one of the world's largest power systems. The masts of this line were designed for eventual upgrade to 380 kV. However the first transmission at 380 kV in Germany was on October 5, 1957 between the substations in
Rommerskirchen Rommerskirchen is the southernmost municipality in the Rhein-Kreis Neuss, in North Rhine-Westphalia, Germany. Notable places Rommerskirchen possesses rich historical inheritances, including numerous remains of the Roman Villae Rusticae, and thos ...
and Ludwigsburg–Hoheneck. The world's first 380 kV power line was built in
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, the 952 km HarsprångetHallsberg line in 1952. In 1965, the first extra-high-voltage transmission at 735 kV took place on a
Hydro-Québec Hydro-Québec is a public utility that manages the generation, transmission and distribution of electricity in the Canadian province of Quebec, as well as the export of power to portions of the Northeast United States. It was established by t ...
transmission line. In 1982 the first transmission at 1200 kV was in the
Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nationa ...
. The rapid industrialization in the 20th century made electrical transmission lines and grids a critical part of the economic infrastructure in most industrialized nations. Interconnection of local generation plants and small distribution networks was greatly spurred by the requirements of
World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...
, where large electrical generating plants were built by governments to provide power to munitions factories; later these plants were connected to supply civil load through long-distance transmission. Small municipal electrical utilities did not necessarily desire to reduce the cost of each unit of electricity sold; to some extent, especially during the period 1880–1890, electrical lighting was considered a luxury product and electric power was not substituted for steam power. Engineers such as
Samuel Insull Samuel Insull (November 11, 1859 – July 16, 1938) was a British-born American business magnate. He was an innovator and investor based in Chicago who greatly contributed to create an integrated electrical infrastructure in the United Stat ...
in the United States and Sebastian Z. De Ferranti in the United Kingdom were instrumental in overcoming technical, economic, regulatory and political difficulties in development of long-distance electric power transmission. By introduction of electric power transmission networks, in the city of London the cost of a kilowatt-hour was reduced to one-third in a ten-year period.Hughes pp. ? In 1926 electrical networks in the United Kingdom began to be interconnected in the National Grid, initially operating at 132 kV.


Power electronics

Power electronics Power electronics is the application of electronics to the control and conversion of electric power. The first high-power electronic devices were made using mercury-arc valves. In modern systems, the conversion is performed with semiconducto ...
is the application of
solid-state electronics Solid-state electronics means semiconductor electronics: electronic equipment using semiconductor devices such as transistors, diodes and integrated circuits (ICs). The term is also used as an adjective for devices in which semiconductor electr ...
to the control and conversion of electric power. Power electronics started with the development of the mercury arc rectifier. Invented by Peter Cooper Hewitt in 1902, it was used to convert alternating current (AC) into direct current (DC). From the 1920s on, research continued on applying
thyratron A thyratron is a type of gas-filled tube used as a high-power electrical switch and controlled rectifier. Thyratrons can handle much greater currents than similar hard-vacuum tubes. Electron multiplication occurs when the gas becomes ionized, p ...
s and grid-controlled mercury arc valves to power transmission.
Uno Lamm August Uno Lamm (May 22, 1904 – June 1, 1989) was a Swedish electrical engineer and inventor. He was sometimes called "The Father of High Voltage Direct Current" power transmission. During his career, Lamm obtained 150 patents. In 1980 the ...
developed a mercury valve with grading electrodes making them suitable for
high voltage direct current A high-voltage direct current (HVDC) electric power transmission system (also called a power superhighway or an electrical superhighway) uses direct current (DC) for electric power transmission, in contrast with the more common alternating curre ...
power transmission. In 1933 selenium rectifiers were invented.


See also

* HVDC converter


References

{{DEFAULTSORT:History Of Electric Power Transmission Electric power transmission Power transmission, history of electrical History of energy de:Elektrifizierung#Geschichtliche Entwicklungen