Early Electrification of Buffalo: Advent of Alternating Current
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. To serve the same
Direct current systems had three major disadvantages:
- Generation had to be located reasonably close to the load due to the voltage drop, which required large size wire.
- Generation had to be at utilization voltage.
- Low utilization voltage meant high currents and high currents meant high losses in the distribution lines.
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.
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 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 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.