Subansiri (Lower)


Subansiri Lower HE Project is a Run of River scheme with small Pondage on river Subansiri. The Project is located near North Lakhimpur on the border of Arunachal Pradesh and Assam. The nearest railhead is Gogamukh/North Lakhimpur and nearest airport is Lilabari / Dibrugarh. The estimated annual energy generation from the Project is 7421.59 MU in a 90% dependable year and 95% Machine Availability. The layout plan, features and photo gallery of the Power Station are detailed below.
 
Image contains layout plan
Feature List
Feature Name Description
Approach Nearest Rail Head is Gogamukh/North Lakhimpur & Nearest Airport is Lilabari / Dibrugarh
Location Located in Lower Subansiri in Arunachal Pradesh and Assam
Capacity 1000 MW (4x250 MW) (Out of 2000 MW)
Design Energy 7421.59 MU (Full Capacity)
Beneficiary States/UTs Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Tripura, Goa, Haryana, U.P, Chhattisgarh, Gujarat, Maharashtra, M.P, Rajasthan, Chandigarh, Delhi
Date of Commercial Operation (COD) Unit # 1: 20/03/2026 Unit # 2 : 23/12/2025 Unit # 3 : 01/02/2026 Unit # 4 : 08/05/2026
Dam 
TypeConcrete Gravity Dam
Height116m
FRL
MDDL		EL 205.00 m
EL 181.0 m
HRT 
Number8
ShapeHorse Shoe, 9.5 m Dia
LengthFrom 608 to 1168 m
Design discharge322.4 cumec
PRESSURE SHAFT 
Number8
ShapeCircular
Diameter8 m
TAIL WATER LEVEL 
Maximum tail water level

 		El 112.0 M
Normal tail water levelEl 108.96 M
Minimum tail water levelEl 105.0 M
Power House 
TypeSURFACE
CapacityComprising of 8 units of 250 MW each
Turbine 
TypeFrancis
Rated Head86 m
Design Discharge322.4 m3/s
No. of GV24
Generator 
Rated continuous output306  MVA
Rated Voltage16±10%kV
No of Poles48
Rated Speed125 rpm
Generator Step up Transformer: (GSU) 
Type1-Ф
Voltage Ratio16 / 400 /√(3 ) kV
MVA Rating102 MVA
Type of coolingOFWF
Switchyard /Potyard 
Switchyard /PotyardGIS (Gas Insulated Switchgear)
Voltage level420 kV 
No. of lines04 Nos (420 kV)
 400KV BISHWANATH CHARIYALI