The Keokuk story [history]

From 1910 to 1913, construction was under way on a huge hydroelectric complex on the Mississippi River at Keokuk, Iowa. Located at the foot of the Des Moines Rapids, the project included a dam that was constructed from Keokuk to Hamilton, Illinois, on the eastern shore of the river. The power plant was separated from the western shore of the river by a navigation lock to permit barge and ship travel past the dam. Originally, all electric power generation at the site was at a frequency of 25 Hz, primarily due to the slow speed of the generators. The major portion of the station´s output was transmitted to the city of St. Louis, Missouri, located about 140 miles to the south. As constructed, the station contained 15 10,000-hp turbines, each driving a 7.5-MW AC generator for a total station output of 112.5 MW. The Keokuk station is still in operation today, but it now generates 60-Hz power. The conversion from 25 Hz began in 1942, but was not completed until 2002.