Wanjii power station is situated in Murang’aCounty  80km from Nairobi. This is a run-of-river plant with a small sized dam having low water storage capacity. It has Mathioya dam on MathioyaRiver and Maragua dam on MaraguaRiver. The source for the two rivers is the Aberdare forest.The station has a total capacity of 7.4MW. Units 1 & 2 are each rated at 2.7MW and they get their water from Mathioya River through a tunnel that is 5.2km long and runs under Murang’a town. The water from these machines flows into MaraguaRiver. Units 3 & 4 are served by MaraguaRiver.A project to modernize and upgrade the units has already been awarded to Voith Hydro, Germany. Site installation works are planned to start in June 2019.

Units 1 & 2 (Merilla units)

Year of commissioning: 1952

Installed capacity: 2 x 2.7MW

Turbine type: Horizontal Francis

Turbine manufacturer:Harland, UK

Design head:  {51.2m – 1 Machine; 40.5m – 2 Machines}

Design speed: 333rpm

Runner type: Vertical Francis runner

Generator manufacturer: UCM Hydro Romania

Generator rating: 9100kVA

Generator voltage: 11000V

Generator current: 478A

Rated power: 7735kW

Frequency: 50Hz

Power factor: 0.85

Excitation voltage: 130V

Excitation current: 520A

Excitation system: Brushes

Units 03 and 04 (Maragwaunits)

Year of commissioning: 1954 units

Installed capacity: 2 x 1.0MW

Turbine type: Horizontal Francis

Turbine manufacture: Harland, UK

Design head: 68.2m

Design speed: 500rpm

Runner type: Vertical Francis runner

Generator manufacturer: UCM Hydro Romania

Rating: 6070kVA

Rated voltage: 11000V

Rated power: 5159kW

Frequency: 50Hz

Power factor: 0.85

Exciter Voltage: 85V

Exciter current: 550A

Excitation System: Brushes

Protection degrees: IP44