Power Generation : Facts and Figures
Akosombo Hydro Plant
Electricity is generated anytime there is a relative motion between conductors (commonly called wire) and a magnet. An electric generator is therefore a machine designed with conductors and magnet, requiring an external prime mover to create the needed relative motion. A common prime mover is a turbine, which is normally coupled to the rotating part of the generator. The electrical and mechanical plant in the powerhouse has undergone a regular maintenance program. In 1988, a study was initiated and completed, to determine the extent of the retrofit work required, and in 1989 the Akosombo Generation
Station Retrofit Project (AGSRP) was started.
Technical Details of the Akosombo Dam
Maximum height from bedrock - 114m (374.00ft) Height at axis from bedrock - 111m (364.17ft) Height above tail water level - 73.2m (240.15ft) Length of main dam at crest - 660m (2165.33ft) Length of saddle dam - 355m (1164.68ft) Width of dam at bed of river - 366m (1200.77ft) Volume of material in main dam - 7943520m 3 (26061100.42ft 3) Area of Lake - 8502sq.km Capacity of Lake - 148 x 10 12 litres Shoreline - 7250km Length of Lake - 400km Height of saddle dam - 37m (121.39ft) Max. operating level - 84.73m (278ft) Min. operating level - 73.15m (240ft) Max. water level ever recorded - 84.25m (276.41ft) on 2nd Nov. 1974 Min. water level ever recorded - 71.86m (235.76ft) on 12th June 1984 Maximum annual inflow ever recorded - 3000m3/s in 1963
Lowest annual inflow ever recorded - 288m3/s in 1983
TECHNICAL DATA Turbine Unit output - 173.1MW (222000hp) (Retrofitted Units) Head (Max) - 68.88m (226ft) Synchronous speed - 115.4 Rev/Min Type of Turbine - Francis, Vertical shaft Manufacturer - VA Tech, Voest Alpine, Austria Generator Rating - 179.95MVA at 14.4KV, 09PFM Manufacturer - General Electric , Canada Exciter Type: - Static (SILCO-5) Manufacturer - General Electric , Canada Unit Transformer Type - Outdoor 3phase Rating - 200MVA, 14.4/161KV Cooling - OFAF Manufacturer - General Electric , Canada Governor Type - Electronic/Hydraulic Manufacturer - Voest Alpine, Austria Penstock Type - Steel, one per unit Diameter - 7.2m (24ft) Length - 112m (368.1ft) to 116m (380ft)
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