Samanalawewa Power Station
Samanalawewa Power Station is located at Kapugala which is about 160km southeast of Colombo east of the town of Balangoda. Samanalawewa reservior and dam is located on the Walawe Ganga immediately downstream of the confluence with the Belihul Oya and immediately upstream of the Matihakke Ara.
The dam is of the rockfill type with a clay core having a crest level of 463.5m, 107.5m above the riverbed level, with crest length of 480m. The dam structure includes an overflow chute spillway with three radial gates on the left bank and a low-level outlet and irrigation discharge outlet also on the left bank. The reservoir impounded by the dam extends approximately 8km on both the Walawe Ganga and Belihul Oya. At the normal retention level of 460m it has a gross storage capacity of 275 x 106 m3 and a live storage capacity of 215 x 106 m3 above the minimum level of 424m.
The intake to the waterway system is located 7km upstream from the dam site. The intake structure includes screens and hydraulically operated wheel gates. The waterway system consists of a 4800m long, 5.5m diameter concrete lined horseshoe shape low pressure tunnel, 18m diameter concrete surge chamber, 4.5 diameter steel lined tunnel 5.15km long and a 3.2m equivalent diameter 655m long steel penstock leading to the power station where it bifurcates to the two turbines. At the top of the penstock are two 3.85m diameter portal valves one connecting to the penstock and the other blanked off on the downstream side of the valve.
The surface power station is located in the left bank of the Katupath Oya. The power station is equipped with two vertical shaft salient pole 3 phase generators each rated at 70.6MW. The generator voltage is 10.5kV and the output is 60MW at 0.85pf at 50Hz. The prime movers are 70.2MW Francis turbine units running at 500rpm, and water discharging into a 580m long tailrace canal. Energy is transmitted from a 132kV switchyard over a double circuit 16km overhead line to a switching station at Balangoda, as well as another double circuit overhead tower line to the Embilipitiya Grid Sub Station.
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- Installed capacity 60 MW X 2
- Expected annual average energy 403 GWh
- Commissioned in 1991
- Main contractors
- Civil – balfa btm
- Electromechanical – GEC Large Machanical
- Hydro mechanical –TOSHIBA
- Located 40 km south-east of Kandy
- Reservoir
- Catchment area : 1891 km2
- Usable water volume : 218 MCM
- Maximum level : 460 m above MSL
- Minimum level : 424 m above MSL
- Headrace
- Circular concrete lined
- 5.5 m diameter
- 4.8 Km length
- Penstock
- Steel circular, 3 m diameter, 178 m length, With surge tank
- Tailrace
- Length : VVV m ; Maximum level : 240 m above MSL; Minimum level : 230 m above MSL
- Generator (ASEA)
- Conventional vertical
- 70600 kVA, 0.8 PF, 10.5 kV, 3888 A
- 88 Hz, 12 poles, 500 ⅓ rev/min
- Exciter : 220 V, 1130 A
- Turbine (TOSHIBA)
- Vertical Francis
- Output : 68 MW @ 320 m effective head (Rated), 83 MW @ 208 m effective head (Maximum)
- Rated discharge : 21 m3/sec
- 500 ⅓ rev/min
