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TTHIS IS THE SECOND PART OF Atwo-part article on the early develop-ment of electric power systems and thecompetition between advocates of directcurrent (dc) and of alternating current(ac) for the generation, transmission,distribution, and utilization of electricalenergy. The first part appeared in theMay/June issue and discussed the inven-tion of the practical incandescent light;the development, chiefly by ThomasEdison, of low-voltage dc power sys-tems; and the work of Nicola Tesla,William Stanley, George Westinghouse,and others in Europe and in NorthAmerica that led to the advent of acpower systems. This second part of thearticle discusses what became known asthe battle of the currents.

Westinghouse ACPower SystemsThe seven U.S. patent appli-cations filed by Nicola Teslain late 1887 comprised acomprehensive ac system ofgenerators, transformers,transmission lines, polyphasemotors, and lighting. Whenthe enterprising Pittsburghindustrialist George Westing-house, recognizing the valueof Teslas work, purchasedthe seven patents andemployed Tesla to furtherdevelop ac power systems,the Westinghouse ElectricCompany equipped itself tomanufacture and marketadvanced, complete ac power

systems. This set the stage for an indus-trial war to determine whether Edisonsdc or Westinghouses ac would be theelectric supply technology to power themassive industrial development thatbegan in the last years of the 19th centu-ry and continues to the present.

The Battle of the CurrentsWhen the Edison companies took theoffensive in 1888, they identified theadvantages of dc as the following:

superior reliability since dc gener-ators could work in parallel, atechnique not then available for ac

the lack of an ac energy meter the lack of an ac motor

the suitability of dc for batterycharging and electroplatingapplications

the perceived absolute safetyof 110- and 240-volt dc as com-pared to the higher ac transmis-sion and distribution voltages.

In 1888, Oliver B. Shallenberger, aWestinghouse staff engineer, developeda magnetic disk meter for ac power. Thisdirect-reading meter was superior to theelectrolytic meter used by Edison in hisdc system and defeated one of the argu-ments of the dc advocates. Further, whileit took the Westinghouse engineeringteam until 1892 to perfect Teslas acinduction motor and to fully develop

two- and three-phase sys-tems for transmitting anddistributing ac power, theprogress made eliminatedEdisons claim of a lack ofan ac motor.

In the summer of 1888,the Edison interests concen-trated their efforts on theclaimed unsafe nature of ac.Harold P. Brown, a self-taught engineer assumingthe title professor,appeared as a supposedadvocate for public safety. Itis now apparent that hereceived some help andencouragement from the dcproponents. As part of hiseffort, Brown appearedbefore audiences in Virginiaand Ohio and electrocuted

Carl L. Sulzberger

hist

ory

triumph of ac, part 2the battle of the currents

George Westinghouse. (Photo courtesy of Westinghouse.)

IEEE power & energy magazine july/august 2003

july/august 2003 IEEE power & energy magazine

animals to demonstratethe effects of ac. Healso urged the NewYork Board of Electri-cal Control to prohibitac voltages of morethan 300 V. Whilemaintaining that low-voltage dc was perfectlysafe, he condemned acvoltages over 300 V asbeing damnable. Edi-son himself spoke infavor of banning the useof ac altogether or atleast limiting voltagesto no more than 300 V.

At about the sametime, Brown was instru-mental in causing NewYork State to replacehanging with electrocu-tion by ac as its methodof carrying out capitalpunishment. While itwas argued that electro-cution would be pain-less and instant becauseelectric energy travels atthe speed of light, it wasnot known how high avoltage or current wasneeded to kill or themechanism and speedof electricity passing through a humanbody. One of the first electric chairs wasinstalled at the Auburn State Prison inupstate New York. It utilized a used West-inghouse generator clandestinelyacquired by Brown with the financialbacking of the Edison interests. Westing-house would not willingly or knowinglysupply the generators for the New Yorkelectric chairs. The first electrocution,that of convicted axe-murderer WilliamKemmler, was conducted on 6 August1890. Because of poor voltage regula-tion, the execution was reportedly a gris-ly affair. Kemmler was first subjected to1,300 V ac for a period of 17 seconds.When it was discovered that he was stillalive, he was then administered about2,000 V ac until his body began to smol-der and burn. This second charge provedlethal. Westinghousing was suggested

as a synonym for electrocution, but theterm did not stick.

By 1891, the claim of the Edisoninterests that dc is inherently safer thanac had subsided. George Westinghousewould later recall:

I remember Tom [Edison]telling them that dc was like ariver flowing peacefully to thesea, while ac was like a torrentrushing violently over a precipice.Imagine that! Why they even hada professor named Harold Brownwho went around talking to audi-ences and electrocuting dogsand old horses right on stage, toshow how dangerous ac was.

In the meantime, Westinghouse hadmade history by installing a 13-mile long

ac transmission line in Oregon fromwaterwheel driven single-phase genera-tors at Willamette Falls to the City ofPortland. This line operated at 4 kV. Thefirst industrial use of ac transmissiontook place in 1891 when Westinghouseinstalled a 3-kV single-phase lineapproximately three miles from a water-wheel generator to the Gold King OreMill in Telluride, Colorado, at an eleva-tion of over 9,000 feet. The ore crusherwas powered by a 100-horsepower syn-chronous motor. The opportunity forelectric power in the Telluride applica-tion arose from the lack of firewoodabove the timberline and the high cost totransport coal for making steam power tothis remote location. The Tellurideinstallation has been designated an IEEEMilestone. This program recognizes,commemorates, and publicizes histori-

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Westinghouse had made history by installing a13-mile long ac transmission line in Oregon fromwaterwheel driven single-phase generators atWillamette Falls to the City of Portland.

The 3-kV transmission line, left, and the acgenerator, above, used to supply power tothe Gold King Ore Mill, Telluride, Colorado,as they appeared in the early 1890s.

cally significant electrical engineeringachievements. The year 1891 also sawthe installation of a 100-mile long ac linefrom Lauffen to Frankfurt, Germany.This three-phase line operated at 30 kVand was installed by the Oerlikon Com-pany. In 1892, a 40-kV ac transmissionline was built a distance of 70 miles froma remote hydroelectric generating stationto Sacramento, California.

Edisons firm, The Edison GeneralElectric Company, held valuable lamppatents but had no participation in oraccess to the ac equipment market. TheThomson-Houston Company had longparticipated in the development of actechnology and the manufacture of acequipment. Business sense prevailed, andthese two companies merged in 1892 toform the General Electric Company. Edi-son was reportedly unhappy that hisname was not included in the name of thenew company. General Electric activelyand immediately entered the acmanufacturing and installationbusiness. Edison was named adirector of the merged company,but he did not take an active partand resigned after a time.

After launching an industrythat essentially ushered in the20th century and created the mod-ern world, Edison exerted littlefurther influence in the electricpower field. Rather, he turned hisfar-ranging inventive genius to anumber of other fields, mostnotably the invention, develop-ment, and commercialization ofmotion picture and storage batterytechnologies and the further per-fection of the phonograph. It isnoteworthy that the man who laboredlong and hard to develop a successfulhigh-resistance lamp filament to reduceline losses so vigorously resisted theadvent of ac and high transmission anddistribution voltages, the very means bywhich line losses could be effectivelyreduced.

Polyphase AC SystemsCome of Age As the battle of the currents cooled inthe early 1890s, Westinghouse continued

to develop Teslas polyphase systemtechnology. One important developmentwas the production of a rotating magnet-ic field for the induction motor by cou-pling two single-phase alternators on asingle shaft with the field windings dis-placed by 90 degrees. This system wasused at the 1893 Chicago Worlds Fair,also known as the Colombian Exposi-tion, which celebrated the 400th Anniver-sary of the first voyage of ChristopherColumbus to the new world.

When the directors of the Expositionasked for bids for lighting the fairgrounds, both Westinghouse and thenewly formed General Electric Compa-ny were bidders. Westinghouse was ableto underbid the General Electric propos-al by more than one half. Reportedly,much of General Electrics estimatedcost was related to the amount of copperwire needed for its planned dc system.Powered by 12 750-kW two-phase, 60-

Hz alternators located in the Hall ofMachinery, more than 100,000 incandes-cent light bulbs based on an 1880Sawyer-Man patent, the rights to whichWestinghouse had acquired, were lit byPresident Grover Cleveland when theExposition opened on 1 May 1893. Inaddition, a complete Tesla polyphasesystem of generation, transmission, and400- to 1,200-V step-up and step-downtransformers was displayed and demon-strated in the Great Hall of Electricity forthe benefit of the Expositions 27 million

visitors. Overall, the 8,000 arc lights andapproximately 130,000 incandescentlamps installed by Westinghouse turnedthe neoclassical Worlds Fair buildingsand fairgrounds into a city of light anddemonstrated that ac systems were bothpractical and available. From that pointforward, ac quickly eclipsed the dcpower system technology espoused byEdison and others.

The 1892-1893 period saw theinvention of the synchronous rotary con-verter with ac slip rings at one end and adc commutator at the other end. Thisdevelopment allowed for the supply ofdc to street car traction systems frompolyphase ac systems. Also, C.F. Scott,a Westinghouse engineer, developed theT transformer design that allowed forstatic conversion between two-phaseand three-phase power.

Finally, the ascendancy of ac powersystems was further confirmed by the

development of the Niagara Falls Pro-ject. Man had long sought to harness thevast power of the Niagara River at Nia-gara Falls. In 1886, the Cataract Con-struction Company was granted a charterto use the equivalent of 120,000 horse-power of the Niagara flow. Plans to cre-ate an industrial city along the river bankto utilize the water power were aban-doned because of the lack of sufficientavailable land for such purpose.

In 1890, the International NiagaraCommission was formed with Sir

72 IEEE power & energy magazine july/august 2003

Westinghouseturned the 1893Worlds Fairbuildings andfairgrounds intoa city of light,demonstratingthat ac systemswere both practi-cal and avail-able.

july/august 2003 IEEE power & energy magazine

William Thomson (later Lord Kelvin)as its chairman. The Commission wasinstructed to investigate and evaluatemeans to put Niagaras immense powerto useful work, and $22,000 in prizemoney was offered in connection with acall for proposals. Seventeen proposalswere received from representatives ofsix countries. In addition to proposals totransmit energy by compressed air,manila and wire rope, water pressure,and other mechanical and hydraulicmeans, there were four proposals usingdc and two using ac. Ultimately, apolyphase ac generation and transmis-sion system was selected in 1893, andWestinghouse provided the first three5,000-horsepower, two-phase alterna-tors operating at 25 Hz and 2,250 V.These largest alternators yet built had tobe designed from scratch. In 18 months,the first was completed. It was installedin April 1895, and the first power wasdelivered in August of that year to thePittsburgh Reduction Company, now theAluminum Company of America, forthe production of aluminum at NiagaraFalls near the Niagara Falls Power Sta-tion. By November 1895, all three of thefirst alternators were completed, and on16 November 1896, a 20-mile-long, 11-kV transmission line to carry ac powerto Buffalo, New York, was energized. Inthe following years, the Niagara Projectwas greatly expanded, and by 1905there were 21 generators in operation intwo power stations.

The application of ac for long-dis-tance power transmission was critical todeveloping and utilizing the power ofNiagara Falls. This project, now desig-nated an IEEE Milestone, was, at thetime, the largest and most spectacularuse of ac in America. By integrating andapplying advances in electrical scienceand technology then occurring on bothsides of the Atlantic Ocean, the NiagaraProject helped set the stage for the uni-versal electrification that was to come.

EpilogueIn the industrial world of 1880, the useof electrical energy was virtuallyunknown. Mechanical power, generallyusing muscle power, water, or steam as

the prime mover, reigned supreme. In thequarter century following 1880, thedevelopment of electric generation,transmission, and distribution systemsand the invention and continual improve-ment of motor drives, switchgear, con-trols, and other electrical devicesprofoundly transformed everyday lifeand industry, thereby making modernsociety possible. The brief but intensebattle of the currents between ac anddc conclusively determined the directionof future development throughout theworld.

Further ReadingJ.D. Ryder and D. G. Fink, Engineersand Electrons; A Century of Electrical

Progress. New York; IEEE Press, 1984.A.M. McMahon, The Making of a

Profession: A Century of ElectricalEngineering in America. New York:IEEE Press, 1984.

C.S. Derganc, Thomas Edison andhis electric lighting system, IEEE Spec-trum, vol. 16, pp. 50-59, Feb. 1979.

Creating the electric age, EPRI J.,vol. 4, no. 2, March 1979.

The Electric century, 1874-1974,Electrical World, June 1974.

Pearl Street, A Centennial Com-memoration, IEEE Power EngineeringSociety, 1982.

H. Freitag, ed., Electrical Engineer-ing: The Second Century Begins. NewYork: IEEE Press, 1986.

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Niagara Falls Power Station no. 2, ca. 1905. (Photo courtesy of the SmithsonianInstitution.)

The brief but intense battle of the currents between ac and dcconclusively determined thedirection of future developmentthroughout the world.

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