Links of Science & Technology

  • PDF / 2,029,959 Bytes
  • 7 Pages / 576 x 777.6 pts Page_size
  • 104 Downloads / 186 Views




Amorphous Metals in Electric-Power Distribution Applications Nicholas DeCristofaro Introduction On April 13, 1982, the Duke Power Company energized an experimental pad-mount distribution transformer in Hickory, North Carolina.1 The transformer, manufactured by General Electric, provided electric power to a local residence. That same month, the Georgia Power Company installed a similar transformer, made by Westinghouse Electric, atop a utility pole in Athens, Georgia.2 It supplied electricity for the exterior lights at the Westinghouse Newton Bridge Road plant. These devices shown in Figure 1 were unique among the nearly 40 million distribution transformers in service in the United States because their magnetic cores were made from an Fe-B-Si amorphous-metal alloy. This new material, produced by AlliedSignal (formerly Allied Chemical), was capable of magnetizing more efficiently than any electrical steel. By replacing grain-oriented silicon steel in the transformer cores, the amorphous metal reduced the core losses of the transformers by 75%. Although distribution transformers are relatively efficient devices, often operating at efficiencies as high as 99% at full load, they lose a significant amount of energy in their use. Because of the number of units in service, coupled with the fact that the core material is continuously magnetized and demagnetized at line frequency, transformers account for the largest portion of the energy losses on electric power distribution systems. It is estimated that over 50 X 109 kWh are dissipated annually in the United States in the form of distribution transformer core losses.3 At today's average electricity generating cost of $0.035/kWh, that energy is worth over $1,500 million. Currently over 1,250,000 amorphousmetal distribution transformers have been installed worldwide, helping electric power utilities improve the efficiency of their transmission and distribution systems. However the application of Febase amorphous metal to transformers would not be a straightforward substitution for grain-oriented silicon steel. The amorphous metal used in transformers is thinner, harder, and more fragile than the silicon steel it replaces. The amor-


factors necessitated changes to the transformer manufacturing process and mandated both laboratory and field testing before energy savings could be made available at a commercially practical cost and with an acceptable reliability. This article traces the developments leading to the commercialization of amorphousmetal distribution transformers.

Figure 1. (a) Experimental General Electric pad-mount amorphous-metal distribution transformer, (b) Experimental Westinghouse Electric polemount amorphous-metal distribution transformer.

phous metal transformer must be compatible with the existing electric power distribution system and must survive 30 years of continuous service. These Links of Science & Technology describes the origin, science, technology, and unique accomplishments of advances in materials science that have had signif