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 lamp street lighting running on high-voltage alternating current (AC), and large-scale low-voltage direct current (DC) indoor incandescent lighting being marketed by Thomas Edison's company. In 1886, the Edison system was faced with new competition: an alternating current system initially introduced by George Westinghouse's company that used transformers to step down from a high voltage so AC could be used for indoor lighting. Using high voltage allowed an AC system to transmit power over longer distances from more efficient large central generating stations. As the use of AC spread rapidly with other companies deploying their own systems, the Edison Electric Light Company claimed in early 1888 that high voltages used in an alternating current system were hazardous, and that the design was inferior to, and infringed on the patents behind, their direct current system.

In the spring of 1888, a media furor arose over electrical fatalities caused by pole-mounted high-voltage AC lines, attributed to the greed and callousness of the arc lighting companies that operated them. In June of that year Harold P. Brown, a New York electrical engineer, claimed the AC-based lighting companies were putting the public at risk using high-voltage systems installed in a slipshod manner. Brown also claimed that alternating current was more dangerous than direct current and tried to prove this by publicly killing animals with both currents, with technical assistance from Edison Electric. The Edison company and Brown colluded further in their parallel goals to limit the use of AC with attempts to push through legislation to severely limit AC installations and voltages. Both also colluded with Westinghouse's chief AC rival, the Thomson-Houston Electric Company, to make sure the first electric chair was powered by a Westinghouse AC generator.

By the early 1890s, the war was winding down. Further deaths caused by AC lines in New York City forced electric companies to fix safety problems. Thomas Edison no longer controlled Edison Electric, and subsidiary companies were beginning to add AC to the systems they were building. Mergers reduced competition between companies, including the merger of Edison Electric with their largest competitor, Thomson-Houston, forming General Electric in 1892. Edison Electric's merger with their chief alternating current rival brought an end to the war of the currents and created a new company that now controlled three quarters of the US electrical business. Westinghouse won the bid to supply electrical power for the World's Columbian Exposition in 1893 and won the major part of the contract to build Niagara Falls hydroelectric project later that year (partially splitting the contract with General Electric). DC commercial power distribution systems declined rapidly in numbers throughout the 20th century; the last DC utility in New York City was shut down in 2007.

Background

thumbnail|right|Very bright arc lighting (such as this one in 1882 New York) could only be used outdoors or in large indoor spaces where they could be mounted high out of people's sight line.

The war of the currents grew out of the development of two lighting systems; arc lighting running on alternating current and incandescent lighting running on direct current. Both were supplanting gas lighting systems, with arc lighting taking over large area/street lighting, and incandescent lighting replacing gas for business and residential indoor lighting.

Arc lighting

By the late 1870s, arc lamp systems were beginning to be installed in cities, powered by central generating plants. Arc lighting was capable of lighting streets, factory yards, or the interior of large buildings. Arc lamp systems used high voltages (above 3,000 volts) to supply current to multiple series-connected lamps, and some ran better on alternating current.

1880 saw the installation of large-scale arc lighting systems in several US cities including a central station set up by the Brush Electric Company in December 1880 to supply a length of Broadway in New York City with a 3,500–volt demonstration arc lighting system. The disadvantages of arc lighting were: it was maintenance intensive, buzzed, flickered, constituted a fire hazard, was really only suitable for outdoor lighting, and, at the high voltages used, was dangerous to work with.

Edison's direct current company

thumb|left|Workmen burying Edison DC power lines under the streets in New York City in 1882. This costly practice played to Edison's favor in public perceptions after several deaths were caused by overhead high voltage AC lines.

In 1878 inventor Thomas Edison 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. By 1882 the investor-owned utility Edison Illuminating Company was established in New York City. Edison designed his utility to compete with the then established gas lighting utilities, basing it on a relatively low 110-volt direct current supply to power a high resistance incandescent lamp he had invented for the system. Edison direct current systems would be sold to cities throughout the United States, making it a standard with Edison controlling all technical development and holding all the key patents. Direct current worked well with incandescent lamps, which were the principal load of the day. Direct-current systems could be directly used with storage batteries, providing valuable load-leveling and backup power during interruptions of generator operation. Direct-current generators could be easily paralleled, allowing economical operation by using smaller machines during periods of light load and improving reliability. Edison had invented a meter to allow customers to be billed for energy proportional to consumption, but this meter worked only with direct current. Direct current also worked well with electric motors, an advantage DC held throughout the 1880s. The primary drawback with the Edison direct current system was that it ran at 110 volts from generation to its final destination giving it a relatively short useful transmission range: to keep the size of the expensive copper conductors down generating plants had to be situated in the middle of population centers and could only supply customers less than a mile from the plant.

Westinghouse and alternating current

thumb|right|Westinghouse Electric Company 1888 catalog advertising their "Alternating System".

In 1884 Pittsburgh, Pennsylvania inventor and entrepreneur George Westinghouse entered the electric lighting business when he started to develop a DC system and hired William Stanley, Jr. to work on it. In 1885 he read an article in UK technical journal Engineering that described alternating current systems under development. By that time alternating current had gained a key advantage over direct current with the development of transformers that allowed the voltage to be "stepped up" to much higher transmission voltages and then dropped down to a lower end user voltage for business and residential use. The high voltages allowed a central generating station to supply a large area, up to long circuits. Westinghouse saw this as a way to build a truly competitive system instead of simply building another barely competitive DC lighting system using patents just different enough to get around the Edison patents. The Edison DC system of centralized DC plants with their short transmission range also meant there was a patchwork of un-supplied customers between Edison's plants that Westinghouse could easily supply with AC power.

thumbnail|left|William Stanley developed the first practical AC transformer for Westinghouse and helped build the first AC systems.

In 1885 Westinghouse purchased the US patents rights to a transformer developed by French engineer Lucien Gaulard (financed by British engineer John Dixon Gibbs). He imported several of these "Gaulard–Gibbs" transformers as well as Siemens AC generators to begin experimenting with an AC-based lighting system in Pittsburgh. That same year William Stanley used the Gaulard-Gibbs design and designs from the Hungarian Ganz company's Z.B.D. transformer to develop the first practical transformer. Expanded to the point where it could light 23 businesses along main street with very little power loss over 4000 feet, the system used transformers to step 500 AC volts at the street down to 100 volts to power incandescent lamps at each location. By fall of 1886 Westinghouse, Stanley, and Oliver B. Shallenberger had built the first commercial AC power system in the US in Buffalo, New York.

The spread of AC

By the end of 1887 Westinghouse had 68 alternating current power stations to Edison's 121 DC-based stations. To make matters worse for Edison, the Thomson-Houston Electric Company of Lynn, Massachusetts (another competitor offering AC- and DC-based systems) had built 22 power stations. Thomson-Houston was expanding their business while trying to avoid patent conflicts with Westinghouse, arranging deals such as coming to agreements over lighting company territory, paying a royalty to use the Stanley AC transformer patent, and allowing Westinghouse to use their Sawyer-Man incandescent bulb patent. Besides Thomson-Houston and Brush there were other competitors at the time, including the United States Illuminating Company and the Waterhouse Electric Light Company. All of the companies had their own electric power systems, arc lighting systems, and even incandescent lamp designs for domestic lighting, leading to constant lawsuits and patent battles between themselves and with Edison.

Safety concerns

thumb|right|The myriad of telephone, telegraph, and power lines over the streets of New York City in a photo of the [[Great Blizzard of 1888. An AC line that fell during the storm led to the electrocution of a boy that spring.]]

Elihu Thomson of Thomson-Houston was concerned about AC safety and put a great deal of effort into developing a lightning arrestor for high-tension power lines as well as a magnetic blowout switch that could shut the system down in a power surge, a safety feature the Westinghouse system did not have. Thomson also worried about what would happen with the equipment after they sold it, assuming customers would follow a risky practice of installing as many lights and generators as they could get away with. He also thought the idea of using AC lighting in residential homes was too dangerous and had the company hold back on that type of installation until a safer transformer could be developed.

Due to the hazards presented by high voltage electrical lines most European cities and the city of Chicago in the US required them to be buried underground. The City of New York did not require burying and had little in the way of regulation so by the end of 1887 the mishmash of overhead wires for telephone, telegraph, fire and burglar alarm systems in Manhattan were now mixed with haphazardly strung AC lighting system wires carrying up to 6,000 volts. Insulation on power lines was rudimentary, with one electrician referring to it as having as much value "as a molasses covered rag", and exposure to the elements was eroding it over time. A third of the wires were simply abandoned by defunct companies and slowly deteriorating, causing damage to, and shorting out the other lines. Besides being an eyesore, New Yorkers were annoyed when a large March 1888 snowstorm (the Great Blizzard of 1888) tore down a large number of the lines, cutting off utilities in the city. This spurred on the idea of having these lines moved underground but it was stopped by a court injunction obtained by Western Union. Legislation to give all the utilities 90 days to move their lines into underground conduits supplied by the city was slowly making its way through the government but that was also being fought in court by the United States Illuminating Company, who claimed their AC lines were perfectly safe.

Edison's anti-AC stance

As AC systems continued to spread into territories covered by DC systems, with the companies seeming to impinge on Edison patents including incandescent lighting, things got worse for the company. The price of copper was rising, adding to the expense of Edison's low voltage DC system, which required much heavier copper wires than higher voltage AC systems. Thomas Edison's own colleagues and engineers were trying to get him to consider AC. Edison's sales force was continually losing bids in municipalities that opted for cheaper AC systems and Edison Electric Illuminating Company president Edward Hibberd Johnson pointed out that if the company stuck with an all DC system it would not be able to do business in small towns and even mid-sized cities. Edison Electric had a patent option on the ZBD transformer, and a 1886 confidential in-house report by electrical engineer Frank Sprague had recommended that the company go AC, but Thomas Edison was against the idea.

After Westinghouse installed his first large scale system, Edison wrote in a November 1886 private letter to Edward Johnson, "Just as certain as death Westinghouse will kill a customer within six months after he puts in a system of any size, He has got a new thing and it will require a great deal of experimenting to get it working practically." Edison seemed to hold a view that the very high voltage used in AC systems was too dangerous and that it would take many years to develop a safe and workable system. Safety and avoiding the bad press of killing a customer had been one of the goals in designing his DC system and he worried that a death caused by a mis-installed AC system could hold back the use of electricity in general. Edison's understanding of how AC systems worked seemed to be extensive. He noted what he saw as inefficiencies and that, combined with the capital costs in trying to finance very large generating plants, led him to believe there would be very little cost savings in an AC venture. Edison was also of the opinion that DC was a superior system (a fact that he was sure the public would come to recognize) and inferior AC technology was being used by other companies as a way to get around his DC patents.

In February 1888 Edison Electric president Edward Johnson published an 84-page pamphlet titled "A Warning from the Edison Electric Light Company" and sent it to newspapers and to companies that had purchased or were planning to purchase electrical equipment from Edison competitors, including Westinghouse and Thomson-Houston, stating that the competitors were infringing on Edison's incandescent light and other electrical patents.

Execution by electricity

thumbnail|A June 30, 1888 [[Scientific American illustration of what the new electric chair might look like.]]

As arc lighting systems spread, so did stories of how the high voltages involved were killing people, usually unwary linemen, a strange new phenomenon that seemed to instantaneously strike a victim dead. One such story in 1881 of a drunken dock worker dying after he grabbed a large electric dynamo led Buffalo, New York dentist Alfred P. Southwick to seek some application for the curious phenomenon. He worked with local physician George E. Fell and the Buffalo ASPCA, electrocuting hundreds of stray dogs, to come up with a method to euthanize animals via electricity. Southwick's 1882 and 1883 articles on how electrocution could be a replacement for hanging, using a restraint similar to a dental chair (an electric chair) caught the attention of New York State politicians who, following a series of botched hangings, were desperately seeking an alternative. An 1886 commission appointed by New York governor David B. Hill, which including Southwick, recommended in 1888 that executions be carried out by electricity using the electric chair.

There were early indications that this new form of execution would become mixed up with the war of currents. As part of their fact-finding, the commission sent out surveys to hundreds of experts on law and medicine, seeking their opinions, as well as contacting electrical experts, including Elihu Thomson and Thomas Edison. In late 1887, when death penalty commission member Southwick contacted Edison, the inventor stated he was against capital punishment and wanted nothing to do with the matter. After further prompting, Edison hit out at his chief electric power competitor, George Westinghouse, in what may have been the opening salvo in the war of currents, stating in a December 1887 letter to Southwick that it would be best to use current generated by "'alternating machines,' manufactured principally in this country by Geo. Westinghouse". Soon after the execution by electricity bill passed in June 1888, Edison was asked by a New York government official what means would be the best way to implement the state's new form of execution. "Hire out your criminals as linemen to the New York electric lighting companies" was Edison's tongue-in-cheek answer.

Anti-AC backlash

As the number of deaths attributed to high voltage lighting around the country continued to mount, a cluster of deaths in New York City in the spring of 1888 related to AC arc lighting set off a media frenzy against the "deadly arc-lighting current" and the seemingly callous lighting companies that used it. These deaths included a 15-year-old boy killed on April 15 by a broken telegraph line that had been energized with alternating current from a United States Illuminating Company line; a clerk killed two weeks later by an AC line; and a Brush Electric Company lineman killed in May by the AC line he was cutting. The press in New York seemed to switch overnight from stories about electric lights vs gas lighting to "death by wire" incidents, with each new report seeming to fan public resentment against high voltage AC and the dangerously tangled overhead electrical wires in the city.

Harold Brown's crusade

thumbnail|Electrical engineer Harold Pitney Brown emerged in June 1888 as an anti-AC crusader.

At this point an electrical engineer named Harold P. Brown, who at that time seemed to have no connection to the Edison company, sent a June 5, 1888 letter to the editor of the New York Post claiming the root of the problem was the alternating current (AC) system being used. Brown argued that the AC system was inherently dangerous and "damnable" and asked why the "public must submit to constant danger from sudden death" just so utilities could use a cheaper AC system.

At the beginning of attacks on AC, Westinghouse, in a June 7, 1888 letter, tried to defuse the situation. He invited Edison to visit him in Pittsburgh and said "I believe there has been a systemic attempt on the part of some people to do a great deal of mischief and create as great a difference as possible between the Edison Company and The Westinghouse Electric Co., when there ought to be an entirely different condition of affairs". Edison thanked him but said "My laboratory work consumes the whole of my time".

On June 8, Brown was lobbying in person before the New York Board of Electrical Control, asking that his letter to the paper be read into the meeting's record and demanding severe regulations on AC including limiting voltage to 300 volts, a level that would make AC next to useless for transmission. There were many rebuttals to Brown's claims in the newspapers and letters to the board, with people pointing out he was showing no scientific evidence that AC was more dangerous than DC. Westinghouse pointed out in letters to various newspapers the number of fires caused by DC equipment and suggested that Brown was obviously being controlled by Edison, something Brown continually denied.

A July edition of The Electrical Journal covered Brown's appearance before the New York Board of Electrical Control and the debate in technical societies over the merits of DC and AC, noting that:

At a July meeting Board of Electrical Control, Brown's criticisms of AC and even his knowledge of electricity was challenged by other electrical engineers, some of whom worked for Westinghouse. At this meeting, supporters of AC provided anecdotal stories from electricians on how they had survived shocks from AC at voltages up to 1000 volts and argued that DC was the more dangerous of the two.

Brown's demonstrations

Brown, determined to prove alternating current was more dangerous than direct current, at some point contacted Thomas Edison to see if he could make use of equipment to conduct experiments. Edison immediately offered to assist Brown in his crusade against AC companies. Before long, Brown was loaned space and equipment at Edison's West Orange, New Jersey laboratory, as well as laboratory assistant Arthur Kennelly.

Brown paid local children to collect stray dogs off the street for his experiments with direct and alternating current. After much experimentation killing a series of dogs, Brown held a public demonstration on July 30 in a lecture room at Columbia College. With many participants shouting for the demonstration to stop and others walking out, Brown subjected a caged dog to several shocks with increasing levels of direct current up to 1,000 volts, which the dog survived. Brown then applied 330 volts of alternating current which killed the dog. Four days later he held a second demonstration to answer critics' claims that the DC probably weakened the dog before it died. In this second demonstration, three dogs were killed in quick succession with 300 volts of AC. Brown wrote to a colleague that he was sure this demonstration would get the New York Board of Electrical Control to limit AC installations to 300 volts. Brown's campaign to restrict AC to 300 volts was unsuccessful but legislation did come close to passing in Ohio and Virginia.

Collusion with Edison

What brought Brown to the forefront of the debate over AC and his motives remain unclear, but historians note there grew to be some form of collusion between the Edison company and Brown. Edison records seem to show it was Edison Electric Light treasurer Francis S. Hastings who came up with the idea of using Brown and several New York physicians to attack Westinghouse and the other AC companies in retaliation for what Hastings thought were unscrupulous bids by Westinghouse for lighting contracts in Denver and Minneapolis. In July 1888 Westinghouse paid a substantial amount to license Nikola Tesla's US patents for a poly-phase AC induction motor and obtained a patent option on Galileo Ferraris' induction motor design. Although the acquisition of a feasible AC motor gave Westinghouse a key patent in building a completely integrated AC system, the general shortage of cash the company was going through by 1890 meant development had to be put on hold for a while. The difficulties of obtaining funding for such a capital intensive business was becoming a serious problem for the company and 1890 saw the first of several attempts by investor J. P. Morgan to take over Westinghouse Electric.

Thomson-Houston was continuing to expand, buying seven smaller electric companies including a purchase of the Brush Electric Company in 1889. By 1890 Thomson-Houston controlled the majority of the arc lighting systems in the US and a collection of its own US AC patents. Several of the business deals between Thomson-Houston and Westinghouse fell apart and in April 1888 a judge rolled back part of Westinghouse's original Gaulard Gibbs patent, stating it only covered transformers linked in series.

With the help of the financier Henry Villard the Edison group of companies also went through a series of mergers: Edison Lamp Company, a lamp manufacturer in East Newark, New Jersey; Edison Machine Works, a manufacturer of dynamos and large electric motors in Schenectady, New York; Bergmann & Company, a manufacturer of electric lighting fixtures, sockets, and other electric lighting devices; and Edison Electric Light Company, the patent-holding company and the financial arm backed by J.P. Morgan and the Vanderbilt family for Edison's lighting experiments, merged. The new company, Edison General Electric Company, was formed in January 1889 with the help of Drexel, Morgan & Co. and Grosvenor Lowrey with Villard as president. It later included the Sprague Electric Railway & Motor Company.

The peak of the war

Through the fall of 1888 a battle of words with Brown specifically attacking Westinghouse continued to escalate. In November George Westinghouse challenged Brown's assertion in the pages of the Electrical Engineer that the Westinghouse AC systems had caused 30 deaths. The magazine investigated the claim and found at most only two of the deaths could be attributed to Westinghouse installations.

Associating AC and Westinghouse with the electric chair

Although New York had a criminal procedure code that specified electrocution via an electric chair, it did not spell out the type of electricity, the amount of current, or its method of supply, since these were still relative unknowns. The New York Medico-Legal Society, an informal society composed of doctors and lawyers, was given the task of working out the details and in late 1888 through early 1889 conducted a series of animal experiments on voltage amounts, electrode design and placement, and skin conductivity. During this time they sought the advice of Harold Brown as a consultant. This ended up expanding the war of currents into the development of the chair and the general debate over capital punishment in the US.

Brown was not slowed down by this revelation and characterized his efforts to expose Westinghouse as the same as going after a grocer who sells poison and calls it sugar. In 1890, he told president Henry Villard he thought it was time to retire from the lighting business and moved on to an iron ore refining project that preoccupied his time. Edison's fierce opposition to AC no longer controlled the company. By 1889, Edison Electric's own subsidiaries were lobbying to add AC power transmission to their systems, and in October 1890, Edison Machine Works began developing AC-based equipment.

With Thomas Edison no longer involved with Edison General Electric, the war of currents came to a close with a financial merger. Edison president Henry Villard, who had engineered the merger that formed Edison General Electric, was continually working on the idea of merging that company with Thomson-Houston or Westinghouse. He saw a real opportunity in 1891. The market was in a general downturn causing cash shortages for all the companies concerned and Villard was in talks with Thomson-Houston, which was now Edison General Electric's biggest competitor. Thomson-Houston had a habit of saving money on development by buying, or sometimes stealing, patents. Patent conflicts were stymieing the growth of both companies and the idea of saving on some 60 ongoing lawsuits as well as saving on profit losses of trying to undercut each other by selling generating plants below cost pushed forward the idea of this merger in financial circles. Edison put on a brave face, noting to the media how his stock had gained value in the deal, but privately he was bitter that his company and all of his patents had been turned over to the competition.

Aftermath

Even though the institutional war of currents had ended in a financial merger, the technical difference between direct and alternating current systems followed a much longer technical merger. Due to innovation in the US and Europe, alternating current's economy of scale with very large generating plants linked to loads via long-distance transmission was slowly being combined with the ability to link it up with all of the existing systems that needed to be supplied. These included single phase AC systems, poly-phase AC systems, low-voltage incandescent lighting, high voltage arc lighting, and existing DC motors in factories and street cars. In the engineered universal system these technological differences were temporarily being bridged via the development of rotary converters and motor–generators that allowed the large number of legacy systems to be connected to the AC grid.

A three-phase three-wire transmission system had already been deployed in Europe at the International Electro-Technical Exhibition of 1891, where Mikhail Dolivo-Dobrovolsky used this system to transmit electric power over a distance of 176 km with 75% efficiency. In 1891 he also created a three-phase transformer, the short-circuited (squirrel-cage) induction motor and designed the world's first three-phase hydroelectric power plant.

Patent lawsuits were still hampering both companies and bleeding off cash, so in 1896, J. P. Morgan engineered a patent sharing agreement between the two companies that remained in force for 11 years.

In 1897 Edison sold his remaining stock in Edison Electric Illuminating of New York to finance his iron ore refining prototype plant. In 1908, Edison said to George Stanley, son of AC transformer inventor William Stanley, Jr., "Tell your father I was wrong", likely an admission that he had underestimated the developmental potential of alternating current.

Remnant and existent DC systems

Some cities continued to use DC well into the 20th century. For example, central Helsinki had a DC network until the late 1940s, and Stockholm lost its dwindling DC network as late as the 1970s. A mercury-arc valve rectifier station could convert AC to DC where networks were still used. Parts of Boston, Massachusetts, along Beacon Street and Commonwealth Avenue still used 110 volts DC in the 1960s, causing the destruction of many small appliances (typically hair dryers and phonographs) used by Boston University students, who ignored warnings about the electricity supply.

New York City's electric utility company, Consolidated Edison, continued to supply direct current to customers who had adopted it early in the twentieth century, mainly for elevators. The New Yorker Hotel, constructed in 1929, had a large direct-current power plant and did not convert fully to alternating-current service until well into the 1960s. This was the building in which AC pioneer Nikola Tesla spent his last years, and where he died in 1943. New York City's Broadway theaters continued to use DC services until 1975, requiring the use of outmoded manual resistance dimmer boards operated by several stagehands. This practice ended when the musical A Chorus Line introduced computerized lighting control and thyristor (SCR) dimmers to Broadway, and New York theaters were finally converted to AC.

In January 1998, Consolidated Edison started to eliminate DC service. At that time there were 4,600 DC customers. By 2006, there were only 60 customers using DC service, and on November 14, 2007, the last direct-current distribution by Con Edison was shut down. Customers still using DC were provided with on-site AC to DC rectifiers. In 2012, Pacific Gas and Electric Company still provided DC power to some locations in San Francisco, primarily for elevators, supplied by close to 200 rectifiers each providing power for 7–10 customers.

The Central Electricity Generating Board in the UK maintained a 200–volt DC generating station at Bankside Power Station in London until 1981. It exclusively powered DC printing machinery in Fleet Street, then the heart of the UK's newspaper industry. It was decommissioned later in 1981 when the newspaper industry moved downstream into the developing docklands area and began using newer AC-powered equipment.

High-voltage direct current (HVDC) systems are used for bulk transmission of energy from distant generating stations, for underwater lines, and for interconnection of separate alternating-current systems.

References

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External links

(AC vs DC an online video mini-history).