High-Power Electronics; November 1993; Scientific American Magazine; by Narain G. Hingorani and Karl E. Stahlkopf; 8 Page(s)

Consumers of electricity are demanding customers. The silicon chips that now pervade daily life, bringing sophisticated behavior to everything from toasters to machine tools, are highly vulnerable to irregularities in their electrical diet. A loss of power for a single cycle of alternating current, one sixtieth of a second, can make computer screens go blank or interrupt other sensitive electronic equipment. At the same time that users of electric power demand quality, they also want more power. As a result, transmission networks are being pressed closer to their operating limits. Yet a range of problems hobbles expansion, and power transfers from one part of the country to another challenge the network's adequacy. All these factors increase the risk of instability and even blackout.

To avoid such problems, the engineers who manage the transmission of electric power must act with extreme caution. They operate the power grid well below its theoretical maximum capacity. The strategy reduces the possibility that a sudden, unforeseen increase in demand or loss of capacity might cause overloads that would ripple outward until they engulfed a significant portion of the nation's transmission network. On the infamous night of November 9, 1965, for example, a blackout struck most of the northeastern U.S. and parts of Canada. Utilities must also maintain large reserves of generating capacity as a safety margin against such contingencies.