Panchakanya Mai Hydro Power Limited

Upper Mai Hydroelectric Project (UMHEP)

The UMHEP is a run-of-the-river (RoR) type hydropower project located in Maimajhuwa and Mabu of Sandakpur Gaupalika of Ilam district in Mechi Zone with an installed capacity of 12 MW. However PPA was signed with Nepal Electricity Authority for 9.98 MW based on Q40 percentile exceedence. The average annual energy generation of UMHEP (9.98 MW) is 55.924 GWh.

Headworks of Upper Mai HEP

Power House of Upper Mai HEP

Salient Features

Upper Mai Hydroelectric Project (9.98 MW)

Hydrology (at intake)
Catchment area of Upper Mai  Khola53.00 km2
Low flow (1 in 2 year)1.32m3/s
Design flow (38 percentile exceedance flow)3.88 m3/s
Long term annual average flow3.63 m3/s

General Hydraulics
Gross head380.80 m
Net head363.7 m
Design flow3.88 m3/s
Installed capacity12.0 MW

Diversion weir
TypeConcrete gravity dam
Crest elevation1628.50 m above msl
Crest length12.00 m

TypeRectangular orifice, Semi-frontal
No of orificeTwo
Size(opening)3.07 m wide X 1.2 m

Under sluice
Invert level1624.30m above msl
Size2.5m X 1.5m
Length11.50 m
Settling Basin:
Number of chambers2
Size (parallel section)30.00 m L X 14.0 m W X 6.25 m avg H
Normal water level1628.43 m above msl
Maximum water level1629.04 m above msl
Top wall level1630.80 m above msl
Top wall level1629.04 m above msl
Size15.75 m long X 3.0m width X 1.6m avg. height
Crest level of spillway1627.04 m above msl
Maximum water level1627.97 m above msl  (for 100 years flood)
Design discharge3.88m3/s

Rate Khola Diversion Tunnel
Tunnel length154.00 m
Size of tunnel1.80m wide x 1.80 m high

Headrace pressure pipe
Total length628.0 m
Internal diameter1.50 m

Headrace tunnel
ShapeInverted D-shape
Length2075.00 m
Cross –section2.00 m wide x 2.50 m high
Cross-section area4.57 m2

Surge shaft
TypeSemi under ground
Internal diameter3.50 m
Height30.8 m

Penstock Pipe
Internal diameter1.20m
Length1576.00 m

Powerhouse and Tailrace
Size27.65 m x 18.0 m x 11.2 m
Turbine axis elevation1247.20 m
Culvert size64.00 m x 2.00 m x 1.50 m

Access road
Length23.2km from Mechi highway

Mechanical and electrical
Rated net head374.90 m
Rated discharge1.94 m3/s
Rated output6000.0 kW x 2
No. of units2
Axis level1247.2 masl
TypeBrushless Synchronous
Capacity6000.0 kW x2
Voltage6.6 kV
No. of units2
TypeThree phase
Rating16 MVA
Voltage ratio6.6 kV/132 kV
Transmission Line
Voltage Level132 kV Single Circuit
Length18.5 KM
ConductorACSR "WOLF"

Energy Generation (9.98 MW)
Dry season energy9.679 GWh
Wet season energy46.244 GWh
Total energy55.924 GWh