I.

LOCATION

1

Country

:

India

2

State

:

Sikkim

3

District

:

West Sikkim

4

Tehsil

:

Soreng

5

River

:

Rangit

6

Name of river basin

:

The Brahmaputra

7

Longitude

:

88° 18' 10" E

II.

TYPE OF PROJECT

1

Type

:

Hydro Electric Project (ROR)

2

Installed capacity

:

120 (3x40) MW

3

Firm Power

:

15.72 MW

4

Annual energy generated during 90% dependable year

:

513 MUs. (Corresponding to 95% availability of the Machine)

III.

HYDROLOGY & CLIMATE

1

Catchment area upto head works

:

1232.00 Sq Km

2

Snow catchment area

:

267.00 Sq Km

3

Average yield

:

3473.00 M Cum

4

Average annual rainfall

:

1551.394 mm

5

Maximum daily rainfall

:

236.90

6

Minimum daily rainfall

:

9.80 mm

7

90% available discharge

:

16.33 Cumecs

8

Maximum Temperature

:

29.2°C

9

Minimum Temperature

:

4.9°C

IV.

DAM

1

Type of Dam

:

Concrete gravity dam

2

Height of Dam

:

44.00 m

3

Top of Dam

:

El. 471.00 m

4

F.R.L.

:

El. 468.00 m

5

M.D.D.L.

:

El. 458.00 m

6

Dead storage level

:

El. 445.00 m

7

Gross storage capacity

:

1.81 M Cum

8

Pond age between F.R.L. and M.D.D.L. (Live storage capacity)

:

1.22 M Cum

9

Dead storage capacity

:

0.59 M Cum

10

Dimension of Spillway gate

:

10.5 m ( W ) x 14 m ( H )

11

Crest elevation (Sluice)

:

El. 445.00 m

12

Type of gate (Sluice)

:

Radial

13

Crest elevation (Ogee)

:

El. 465.00 m

14

Type of gate (Ogee)

:

Vertical lift

15

Length of Dam at top

:

135.3 m

V.

SUBMERGENCE AT F.R.L.

1

Area under submergence

:

13.25 Ha

2

Number of villages affected

i) Full

:

Nil

ii) Partial

:

Nil

3

Number of persons/families to be rehabilitated

i) Urban

:

Nil

ii) Rural

:

42 families

VI.

DESILTING CHAMBER

1

Type of Desilting chamber

:

Underground

2

Number of Desilting chambers

:

3

3

Dimension of single Desilting chamber

:

120 m (L) x 13 m (W) x 15 m (H)

4

Size of silt particle to be removed

:

0.25 mm and above

5

Average flow velocity

:

25.30 cm/sec

VII.

HEAD RACE TUNNEL

1

Type of Head race tunnel

:

Modified horse shoe

2

Dia of Head race tunnel

:

6.40 m

3

Length

:

6488.00 m

4

Slope

:

1 in 478

5

Design Discharge

:

128.00 Cumecs

6

Number of Adits

:

2 Nos.

VIII.

VETILATION SHAFT

1

Dia of Vertical shaft from El. 523m to 493.7m

:

7m

2

Dia of Vertical shaft from El. 493.7m to Overt of HRT

:

4m

3

Height upto overt of HRT

:

73.5m

IX.

SURGE SHAFT

1

Type of Surge shaft

:

Restricted orifice, Semi-underground

2

Dia of Surge shaft

:

18.00m

3

Dia of orifice

:

2m

5

Maximum downsurge level

:

El.445.7 m

6

Top elevation of Surge shaft

:

El. 492.00m

7

Bottom elevation of Surge shaft

:

El. 427.0 m

8

Height of Surge Shaft

:

59 m

X.

PRESSURE SHAFT

1

Type of Pressure shaft

:

Underground

2

Dia of Pressure shaft

:

5.50 m

3

Length of Pressure shaft

:

247 m

4

Thickness of Steel liner

:

20 mm to 36 mm

XI.

POWER HOUSE

1

Type of Power house

:

Surface

2

Length of Power house

:

75.30 m

3

Width of Power house

:

20.20 m

4

Height of PH from lowest excavated level

:

41.385m

5

Centre to centre spacing of units

:

16.50 m

6

Length of service bay

:

18.60 m

7

Distance between A line to B line

:

9.60 m

8

Distance between B line to C line

:

9.00 m

9

Distance between C line to D line

:

11.20 m

10

Centre line of Turbine

:

El. 344.0 m

11

Turbine floor level

:

El. 344.835 m

12

Upper generator floor level

:

El. 352.835 m

13

Lower generator floor level

:

El. 348.835 m

14

Service bay level

:

El. 355.00 m

15

Top elevation of Roof truss

:

El. 374.00 m

16

Number of Machine

:

3

17

Type of Turbine

:

Vertical Francis

18

Rated unit capacity

:

40 MW

19

Specific speed

:

178.38 rpm

20

Synchronous speed & frequency

:

250 rpm, 50 Hz ± 5%

21

Generator rated capacity

:

44.45 MVA with 10% continuous overload

22

Power factor

:

0.9

23

Generator voltage

:

11 KV ± 5%

24

Excitation system

:

Static

25

Heaviest component to be transported

:

25 T

26

Power House crane

:

1 No., 150/30T

27

Max. Gross Head

:

123.50m

28

Max. net head with one M/c. running at rated head

:

118 m

29

Minimum net Head

:

97.0 m

30

Rated net Head

:

103.67 m

31

Minimum tail water level

:

El. 344.50 m

32

Max. tail water level under PLF

:

El. 354.0 m

33

Max. tail water level with three M/c. in operation

:

El. 347.1 m

34

Design Discharge

:

128.0 Cumecs

35

Unit Penstock diameter

:

3.2 m (after trification)

XII.

TAIL RACE CHANNEL

1

Tail Race Channel Size

:

Rectangular, Length about 42.00m

XIII.

GENERATOR TRANSFORMERS

:

16.50 MVA, 11/220/√3 KV Single phase- 10 nos.

XIV.

SWITCHYARD

1

Type of Switchyard

:

220kV GIS Indoor

2

Number of bays in the switchyard

:

6 nos.

XV.

EVACUATION OF POWER

:

Double Circuit 220kV line from Power House to New Melli Pooling station (About 3.2Km.)