Edison and the Electric Chair_ A Story of Light and Death - Mark Essig [120]
Although the exhibits showcased the electrical future, the real revolution at the fair was the system providing the power. In 1893 electrical equipment ran on many types of current, with the division between alternating and direct current being only the most basic. Alternating generators produced current of different types—known as one-, two, and three-phase—that were not interchangeable. Arc lamps required high pressures (1,000 to 2,000 volts), incandescent lamps low (50 to 100 volts). Power needs were even more numerous. The new alternating motors worked well for devices that ran at a constant speed, such as dentist's drills and fans, but electric streetcars and elevators—the two major uses for electrical power in the 1890s—required direct-current motors, which were better equipped to run at varying speeds under heavy loads. Individuals, companies, and municipalities had invested in many different kinds of electrical equipment. The Pearl Street district in New York could not afford to scrap its direct-current lighting system and start all over with alternating, just as an early Westinghouse lighting company that was heavily invested in single-phase alternating current could not convert to two- or three-phase. And any city with electric railways needed direct current to run them. It was like having a dozen railroads, each running on a different-gauge track. The current, ad hoc solution to the problem of incompatibility was to generate different types of electricity for each application.
Together with Nikola Tesla, George Westinghouse created a universal system of electrical supply At the core of the Tesla Polyphase System used at Chicago was a two-phase alternating generator (soon three-phase would become the industry standard). Flexibility was provided by new coupling devices, such as phase-converters that changed two- or three-phase current into single-phase. Even more important was a device called a rotary converter that was capable of changing alternating current into direct. The universal system could supply, from one generator, electricity to serve any need: direct-current motors, single-phase or polyphase alternating motors, electrochemical processes (which required direct current), and incandescent and arc lamps requiring direct current, single-phase, or polyphase alternating current.19
George Westinghouse's bid for the Chicago fair contract was so low that he lost money on it, but the true purpose of his Chicago installation was to stake a claim to Niagara. Not accidentally, the Westinghouse univeral system was perfectly adapted to meet the needs of the Niagara power station. In the fall of 1893, not long after the fair closed, Westinghouse won the Niagara contract. Two years later Niagara delivered power to its first customer, the Pittsburgh Reduction Company, which built near the falls to exploit the cheap electricity. In 1896 Buffalo received its first Niagara power, and before long growing demand forced an expansion of transmission lines. Although Westinghouse won the initial contract, Niagara was very much a cooperative affair. General Electric built transformers, transmission lines, substations, and rotary converters. When generating capacity was expanded, the company supplied some of the new generators. By 1900 Westinghouse and General Electric together controlled virtually all of the electrical manufacturing market, and both firms prospered throughout the next century,20
The Westinghouse Electric and General Electric exhibits at the World's Columbian Exposition in Chicago, 1893.
The Niagara project marked the symbolic victory of alternating over direct current, but Thomas Edison's beloved current did not disappear. Some of Niagara's heaviest customers used direct current for streetcars, industrial motors, and electrochemistry, and Edison's old three-wire direct-current systems in