Maranhão Dam
| Maranhão Dam | ||
|---|---|---|
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| location | ||
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| Coordinates | 39 ° 0 '54 " N , 7 ° 58' 33" W | |
| country |
 Portugal
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| place | Portalegre District | |
| Waters | Seda | |
| Height upstream | 130 m | |
| power plant | ||
| owner | Associação de Regantes e Beneficiários do Vale do Sorraia | |
| Start of planning | 1952 | |
| Start of operation | 1957 | |
| technology | ||
| Average height of fall |
6.22 to 43.48 m | |
| Expansion flow | 2 to 6 m³ / s | |
| Standard work capacity | 3 million kWh / year | |
| Turbines | 1 Francis turbine : 2 MW | |
| Generators | 1 × 2.45 MVA | |
| Others | ||
The Maranhão Dam ( Portuguese Barragem do Maranhão ) is located in the Alentejo region of Portugal in the Portalegre district . It dams the river Seda , a left (southern) tributary of the Tejo , to a reservoir (port. Albufeira da Barragem de Maranhão ). The small town of Avis is about five kilometers upstream from the dam on the left side of the reservoir. About ten kilometers northwest of the Maranhão dam is the Montargil dam .
The project to build the dam began in 1952. The construction was completed in 1957. In addition to irrigation, the dam is also used to generate electricity. It is owned by the Associação de Regantes e Beneficiários do Vale do Sorraia .
Barrier structure
The barrier structure is a dam with a height of 55 m above the foundation level (49 m above the river bed). The crest of the dam is at a height of 133 m above sea level . The length of the top of the wall is 204 m and its width 10 m. The volume of the structure is 592,000 m³.
The dam has both a bottom outlet and a flood relief . A maximum of 44 m³ / s can be discharged via the bottom outlet, and a maximum of 1,600 m³ / s via the flood discharge. The design flood is 2,200 m³ / s; the probability of this event occurring has been determined to be once in 500 years.
Reservoir
With the normal storage target of 130 m (maximum 130.9 m at high water), the reservoir extends over an area of around 19.6 km² and holds 205.4 million m³ of water - 180.9 million m³ of this can be used. The minimum congestion destination at which the machines can still be operated is 111 (or 110.9) m.
power plant
With an installed capacity of 2 MW , the Maranhão power plant is one of the smallest hydropower plants in Portugal. The average annual generation is 3 (or 13.1) million kWh .
The Francis turbine was supplied by VA Tech Escher Wyss . It is located in a machine house at the foot of the dam. The turbine has a maximum output of 2 MW, while the associated generator has an output of 2.45 MVA . The rated speed of the turbine is 500 rpm. The nominal voltage of the generator is 6 kV . In the switchgear , the generator voltage of 6 kV is increased to 30 kV by means of a power transformer.
The minimum height of fall is 6.22 m, the maximum 43.48 m. The minimum flow is 2 m³ / s, the maximum is 6 m³ / s.
