Saturday, November 24, 2007

New York, the city that Thomas Edison electrified 125 years ago, has completed the transition from direct to alternating current, helping to erase the vestiges of a feud between giants of invention.

Last week, the Consolidated Edison utility pulled the plug on direct-current service. Electric operations manager Fred Simms, a Con Ed employee for 52 years, cut a ceremonial cable on a Manhattan street.

The change means that Con Ed now exclusively uses the alternating-current system invented by Nikola Tesla. The utility is named for Edison, whose Pearl Street Station in Manhattan was the nation's first central electrical power plant, serving 59 customers with direct current starting in 1882.

In the so-called "war of currents," Edison feuded with Tesla and George Westinghouse over which transmission method to adopt -- even publicly electrocuting animals in an attempt to show that AC was too dangerous.

AC, however, proved superior, as transformers allowed electricity to travel over long-distance wires. Con Ed froze the development of the DC system in 1928 but continued to supply New York's major DC customers with the existing system.

In January 1998, Con Ed began to eliminate DC service. At that time, there were more than 4,600 DC customers. By last year, there were 60.

Con Ed spokesman Robert McGee said some of the city's elevators still operate with DC using rectifiers that convert the utility's AC service.

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