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Idukki Hydro Electric Project

Capacity - (6 x130MW)

Idukki Hydro Electric Project (IHEP) is the largest hydro electric project in Kerala. Installed capacity of this project is 780 MW. The powerhouse has six generators of 130 MW capacity each . The project was completed with aid from the Government of Canada and the technical consultancy was M/s Surveyor, Nenniger and Chenevert . The project was dedicated to the nation on 12th February 1976 by the then Prime Minister of India, Mrs. Indira Gandhi.There are three Dams associated with this project. They are:  Idukki Arch Dam, Cheruthoni Dam & Kulamavu Dam.
The underground Power Station is a technological achievement in many aspects. The Power House cavern with length of 141 meters,   20 meters in width and 34.5 meters in height is the biggest of its kind in the country. The entry to this cavern is through an access tunnel,599 meters in length. Vertical  Pelton Turbines are used in the station .There are six generating units each of 130 MW capacity.The 220KV Switchyard is situated outside the powerhouse cavern and it is from here that power generated in the station is transmitted to load centers. There are seven 220KV feeders for this purpose. The power generated in the powerhouse is taken to the switchyard through 220KV oil filled cables. After Power generation water from the power station is released to the Thodupuzha River through an underground tunnel, 1220 meters in length.This tail race water is used for power generation in the Malankara Small Hydro Electric station and also for the irrigation purpose with the help of Irrigation dam at Malankara.


Location with district :Idukki in Idukki District
Category :Hydro Power Project
Capacity : …780MW
River :Periyar
Dam :Idukki Arch Dam, Cheruthoni Dam and Kulamavu Dam
Annual Energy Potential :2148 MU

Reservoir :

Catchment Area : …640. Sq. K.M (247.1. Sq. Miles)
Gross Storage :1996.3 MCM
Effective storage at FRL – 1459.5 MCM
Energy Equivalent at FRL- 2145.47 MU
Generation per MCM :…1.47. MU
Design Head :660 Mts.
Full Reservoir level (FRL) :2403.6 Ft. (732.62 M)
Min. Draw Down Level (MDDL) :…2280 Ft.
Design Disch. Through one Machine:…25. M3

Date of Commissioning:

Unit          Rating           Date of Commssioning

U # 1         130 MW              12.02.1976
U # 2         130 MW              07.06.1976
U # 3         130 MW              24.12.1976
U # 4         130 MW              04.11.1985
U # 5         130 MW              22.03.1986
U # 6         130 MW              09.09.1986

Date of Renovation:

Unit – 1 :14.07.2020
Unit – 2 :18.01.2020
Unit – 3 :16.03.2019


1. TURBINE                                                                      

a) Type :Impulse Turbine – Vertical Six jet Pelton wheel
b) Make :Stage -1– NEYRPIC : Stage -2 – Dominion Engineering, Works, Canada
c) Design Net Head :660 Mts.
d) Rated Output :130MW
e) Output Max./ Min : 130 MW/…30. MW
f) Normal Speed : …375 RPM
g) Runway speed : …625 RPM
h) Disc. Through Machine : …25 M3


a) Type :Salient Pole Synchronous Generator
b) Make :Stage -1 -Canadian General Electric: Stage 2- Marine Industries Ltd, Canada
c) Rated Voltage : …11000 V
d) Rated Out put : …144..KVA
f) Speed :375 RPM
g) Power Factor :


a) Type :SHELL Type, Single phase, Delta/Star
b) Make :TELK/Crompton Greaves
c) Rated Voltage : 11000/220000V
d) Rated Out put : …48000..KVA

4. Power Evacuation

         Voltage level              Feeder Name

  1. 220 KV                    Idukki – Pallivasal (IDPV)
  2. 220 kV                    Idukki – New Pallom (IDNE)
  3. 220 kV                    Idukki – Kalamassery 1(IDKL-1)
  4. 220 kV                    Idukki – Kalamassery2 (IDKL-2)
  5. 220 kV                    Idukki--Kothamangalam (IDKM)
  6. 220 kV                    Idukki Lower Periyar -1 (IDLP-1)
  7. 220 kV                    Idukki Lower Periyar -2 (IDLP-2)
  8. 66 kV                      Moolamattom – Vazhathope Feeder (IDVZ)
  9. 66 kV                      Moolamattom – Thodupuzha Feeder (IDKK)
  10. 66 kV                      Moolamattom- Malankara Feeder (IDML)


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