25 Hz at Bethlehem Steel

The history articles in the January/February and March/April 2008 issues of IEEE Power & Energy Magazine described the establishment of a 25-Hz alternating current (ac) system for electric power distribution in the Niagara Falls, New York, region during the 1890s. The choice of this low frequency was related to the use of large ac generators operating at slow speeds as well as the use of slow speed rotary converters to provide direct current (dc) power for then existing distribution networks in downtown Buffalo. Similarly, the use of 25-Hz power became standard in steel mills during the early 20th century as a result of the extensive use of large, slow-speed gas engines to drive alternators.