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Early Electrification of Buffalo: Advent of Alternating Current

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Figure 2.1   Pearl Street Station
Figure 2.1 Pearl Street Station

This article is Part 2 of a 14 Part series.

Previous: Part 1 of 14: Early Electrification of Buffalo: The Beginning of Central Station Service

In September 1882, the Pearl Street Station of the Edison Electric Illuminating Company in New York City went into operation serving 85 customers with some 400 incandescent lamps [Fig. 2.1]. This central station system, which was designed to serve an area approximately one-mile square, consisted of constant voltage direct current generators connected in parallel serving radial circuits with lamps connected in parallel.i 110 volts was selected on the basis of economics with copper being the

Figure 2.2   Edison Central Station DC System
Figure 2.2 Edison Central Station DC System
largest cost [Fig. 2.2].ii It is remarkable that in the last century the voltage has been adjusted upward only slightly to today’s standard of 120 volts. 

The next important development came less than one year later in July 1883 when a three-wire system went into operation in Sunbury, Pennsylvania with a 62 1/2 percent saving in copper compared to the New York system [Fig. 2.3].iii To serve the same

Figure 2.3   Edison Central Station three wire DC system
Figure 2.3 Edison Central Station three wire DC system
load with two generators connected in series, the current is cut in half. The neutral current is zero with equal loads on both generators.
Direct current systems had three major disadvantages:

  1. Generation had to be located reasonably close to the load due to the voltage drop, which required large size wire.
  2. Generation had to be at utilization voltage.
  3. Low utilization voltage meant high currents and high currents meant high losses in the distribution lines.

Figure 2.4   Alternating Current System
Figure 2.4 Alternating Current System
The adoption of alternating current systems overcame these disadvantages. While Edison was improving the dc system, others were developing the alternating current system, which, by using transformers, could raise the generation voltage and utilize small conductors for distribution, then lower the voltage for loads remote from the generation [Fig. 2.4]. The safety problem of a transformer insulation breakdown applying high-voltage to the secondary was solved by the simple but effective expedient of grounding the transformer secondary winding.iv

The first alternating current central station to operate commercially in the United States was placed in service in Buffalo on November 30, 1886 only four years after Edison’s Pearl Street Station. It was a Westinghouse 400 lamp single-phase (or two-wire) system with a primary of 1000 volts. The generator was located in the Brush Electric Light plant at Wilkeson and Mohawk Streets. One customer was the Adam, Meldrum & Anderson department store on downtown Main Street, now the site of the Main Place Mall.v

Figure 2.5   Nikola Tesla
Figure 2.5 Nikola Tesla
The following year in Montpelier, Vermont an ac system replaced a dc system and
2.6   George Westinghouse
2.6 George Westinghouse
the value of the copper salvaged was enough to cover the cost of Also in 1887 a French syndicate was gaining a monopoly on the world’s copper supply and forced up the price nearly 70 percent.vii This made ac systems, which used smaller conductors, more attractive. And you thought that technology changed fast only in recent years! How’s your five-year-old computer doing?

Early ac systems had one major disadvantage: there was no commercially available ac motor. This shortcoming was solved in fairly short order. On May 1, 1888 Nikola Tesla [Fig. 2.5] was issued his first set of patents for a comprehensive system of generators, transformers, synchronous motors and induction motors for the transmission and utilization of two or more alternating currents -- what came to be known as the polyphase system. Two months later, George Westinghouse [Fig. 2.6] acquired the patent rights and Tesla’s services.

During development of the polyphase motor it was found necessary to reduce the alternations from 133 Hz. or cycles per second (the more or less standard frequency for the early single-phase systems) to 60 Hz. This remains the standard North American frequency. Tesla also developed several “split phase” designs for motors for the single-phase systems.

Next: Part 3 of 14: Early Electrification of Buffalo: Developing a Renewable Energy Source


i. “Engineering the Electric Century: Pearl Street Station inaugurates an era,” Electrical World, May 15, 1973: 33.

ii. Christopher S. Derganc, “Thomas Edison and His Electric Lighting System,” IEEE Spectrum, February 1979:56.

iii. “Engineering: Pearl Street,” 34.

iv. “Engineering the Electric Century: As dc distribution limits loomed, higher voltages of ac systems promised a solution,” Electrical World, June 15, 1973: 74.

v. “Niagara Mohawk Story,” 69. “dc distribution limits,” 75. Charles A. Ruch, “A Young Westinghouse is Challenged,” Westinghouse Retirees’ News, March 1993:6. Edward Dean Adams, Niagara Power: History of the Niagara Falls Power Company 1886-1918, 2 vols., (Niagara Falls, NY: Privately printed for The Niagara Falls Power Company MCMXVIII, 1927), 2:170.

vi. “dc distribution limits,” 75.

vii. “The Copper Ring and the Senate Tariff Bill,” New York Times, 30 Nov 1888.