NHPC parbati project- 2 Kullu Himachal Pradesh Mechanical training report.

1. PARBATI HYDROELECTRIC PROJECT
STAGE-II, sainj, kullu
(Himachal Pradesh)
A REPORT ON INDUSTRIAL TRAINING
Submitted by-
Deepak Chaudhary
Mechanical Engineer
Z.H College of Engineering & Technology
AMU Aligarh, Uttar pradesh
Submitted to-
Mr. Sudhir Negi
Senior Manager (Mechanical & Electrical)
PHEP steg-II
Duration of Training- From 14/07/2018 to 2/08/2018

2. Preface
Technical study can never be completed without practical experience of the field.
Technical study has got two sides one is theoretical aspect and other is field experience. Theory
of any subject is important but without its practical knowledge it becomes useless, particular for
technical students.
During training, I tried to learn about the various operations taking place in plant. I tried
to get into details of Mechanical and electrical machines, their use and specifications. As an
engineering student I must know why a particular kind of machine/Component is used for a
particular application and this could only be learned in a practical atmosphere which was
provided by PHEP-II. I also tried to observe an important aspect of industrial management i.e.
discipline and safety precaution taken by the industries. We saw how engineers co-ordinate with
working staff for smooth running of plant.
This report consists of various aspects of power house (generation of power, its
transformation and distribution) at Parbati Hydroelectric Project Stage-II, NHPC. In this report I
have given a brief introduction about various Electrical machines, generators, field devices,
transformers, cranes, motors, Earthing, valves and circuit breaker system and their
characteristics.
I would just like to say that during this vocational training I got a chance to experience
the real industrial world and fill the gap between theoretical knowledge and practical
knowledge. I am deeply indebted to all the engineers for their support and cooperation.

3. Acknowledgement
The successful completion of any task would be incomplete without mentioning the
people who have made it possible. So it is with the gratitude that I acknowledge the help, which
crowned my efforts with success.
I would like to express my sincere thanks to the management of NHPC who gave me the
opportunity to work and study in such an esteemed organization. It is a matter of pride for me to
acknowledge my gratitude to respected Senior Manager (Mechanical & Electrical) Mr. Sudhir
Negi, who always facilitates me in gaining practical knowledge and Mr. Arun kumar & Mr.
Frank nama for their regular Instructions and Guidance.
Last but not the least, I would like to thank all who supported me in this study by way of
sparing their precious time, providing relevant information and sharing experience, I needed,
without which this Training would have been incomplete.
Trainee-
Deepak Chaudhary

4. Table of content
1. Introduction
 About Hydroelectric power plant
 About NHPC
 About Parbati Hydroelectric projects
2.Parbati project Stage- II
 Features
 Technical features
 Typical layout
3. Major components of PHEP-II:
 Dam and its associated parts
 Water conducting system
 Power house
4. Components of Power house-
a).Main inlet valve
b).Generation system
I ).Turbine
II). Generator
c).Transmission system
I). Transformer
II). GIS
III). Pothead yard
5. Hydro Technology FAQ’s:
6. Conclusion
7. Sources

5. Introduction about Hydroelectric power plant:
In this water jet is used to turn a propeller like piece called as Turbine, which then a turn metal
shaft in an Electric generator, which is the part that produces Electricity. Then through various
means the electricity transferred to main supply.
The theory is to build a dam on a large river that has a large drop in elevation. The dam stores
lots of water behind it in the reservoir at FRL ( full reservoir level)and a live storage of 1.98
Mcum . Near the bottom of the dam wall there is the water intake. Gravity causes it to fall
through the penstock inside the dam. At the end of the penstock there is a turbine propeller,
which is turned by the moving water. The surge shaft (restrict the surges within the height of
shaft) from the turbine goes up into the generator, which produces the power. Power lines are
connected to the generator that carry electricity to your home and mine. The water continues
past the propeller through the tail race tunnel (TRT) into the river past the dam. By the way, it
is not a good idea to be playing in the water right below a dam when water is released.
"A hydraulic turbine converts the energy of flowing water into mechanical energy. A
hydroelectric generator converts this mechanical energy into electricity. The operation of a
generator is based on the principles discovered by Faraday. He found that when a magnet is
moved past a conductor, it causes electricity to flow. In a large generator, electromagnets are
made by circulating direct current through loops of wire wound around stacks of magnetic steel

6. laminations. These are called field poles, and are mounted on the perimeter of the rotor. The
rotor is attached to the turbine shaft, and rotates at a fixed speed. When the rotor turns, it causes
the field poles (the electromagnets) to move past the conductors mounted in the stator. This, in
turn, causes electricity to flow and a voltage to develop at the generator output terminals."
Benefits of Hydropower
Hydropower is a renewable, economic, non polluting and environmentally benign source of
energy. It saves scarce fossil fuel resources of the country, which are non renewable.
Hydropower projects have certain distinctive advantages over other sources of electricity
generation, as discussed below:
a) Technical Benefits
 Hydropower projects are known to have much longer life and provide cheaper electricity as
there is no fuel cost and the recurring cost involved in generation, operation and
maintenance is lower than that in case of other sources of energy.
b) Environmental Benefits
 Uses renewable and pollution free source i.e water
 Increase in Agriculture Productivity through development of irrigation and multipurpose
schemes, having generation of electricity as one of the objectives, wherever possible and
feasible.
 Avoided Green House Gas (GHG) emissions from equivalent thermal and other fuel based
power projects.
 Involve large scale afforestation activities under various schemes like Compensatory
Afforestation, Catchment Area Treatment, Green Belt Development, Voluntary
Afforestation etc. which ultimately improve the environmental quality of the project area.
 Flood Mitigation through large storage dams.
 Source of Drinking Water
c) Social Benefits
 Hydro projects are a boon to the society and the population in and around the projects. With
enhanced employment opportunities, increased earnings, enriched life style and improved
standard of living, the people in these localities experience an economic and social
upliftment. Reservoir area is an ideal place for recreation and source of eco-tourism
promotion in the area. The reservoirs are also used for promoting pisciculture. There are
other direct benefits accruing from hydro projects and dams such as increased water for
improved irrigation, and drinking water to villages and people living in and around the
project area.

7. Introduction about NHPC:
NHPC Limited, a Govt. of India Enterprise, was incorporated in the year 1975 with authorized
share capital of Rs. 2,000 million and with an objective to plan, promote and organize an
integrated and efficient development of hydroelectric power in all aspects. Later on NHPC
expanded its objects to include development of power in all its aspects through conventional
and non-conventional sources in India and abroad.
At present, NHPC is a Mini Ratna Category-I Enterprise of the Govt. of India with authorized
share capital of Rs. 1,50,000 Million. NHPC is ranked as a premier organization in the country
for development of hydropower.
Initially, on incorporation, NHPC took over the execution of Salal Stage-I, Bairasiul and Loktak
Hydro-electric Projects from Central Hydroelectric Project Construction and Control Board.
Since then, it has executed 20 projects with an installed capacity of 6507 MW on ownership
basis including projects executed by NHDC Limited, a Subsidiary Company of NHPC Limited.
NHPC has also executed 5 projects with an installed capacity of 89.25 MW on turnkey basis.
Two of these projects have been commissioned in neighbouring countries i.e. Nepal & Bhutan.
During the financial year 2016-2017, NHPC Power Stations achieved the generation of 23275
MU.
At present NHPC has 7000+ Employees, 23 power stations, 7047MW installed capacity and 2
construction projects.
NHPC’s earn Rs. 2765 crore during FY 2017-18.

8. Location of NHPC

9. Introduction about Parbati Hydroelectric project:
Parbati Hydroelectric Project is a cascade development to be developed in 3 stages with an
aggregate generating capacity of 2070 MW. Stage-I is storage type of scheme and situated in
the mainly snow bound area having installed capacity as 750 MW. Parbati Project Stage-II is
a run of the river scheme and shall have installed capacity of 800MW. Parbati Project Stage-
III development is downstream of Stage-II and shall have installed capacity of 520 MW.
Parbati Stage-II comprising of 83.7m high Concrete Gravity Dam and 31.525 km long HRT
shall be utilizing a gross head of 862 m. To enhance the generating capacity of the Project 5
small streams shall also be trapped. The project is of special importance as the longest reach of
9 km shall be excavated with the use of TBM and 2 Nos inclined Pressure Shafts each about
1.546 km long is also excavated with TBM. The total quantum of underground works involving
tunneling shall be about 57 km.
The Beas valley in Himachal Pradesh has a vast potential for water resources development and
only a small part has been tapped during the past five decades of planned development. Parbati
River, Hurla nallah and Sainj River are major tributaries of Beas River in Kullu valley. Parbati
River is the northernmost left bank tributary of river Beas in Kullu District of Himachal
Pradesh. The river Parbati is a glacial and snow fed river and it originates from Mantalai Lake
from snow peaks at an elevation of 6300 m and traverses in northerly direction and flows down
as a small stream in a narrow valley. After traversing 7 km from its origin it joins the Beas
River at Bhuntar. The river in general can be termed as a very fast flowing and ferocious one.
The river valley is located in high mountain ranges, which rises to more than 1,000 m on both
the banks over most of its stretch. The stream Dibi ka nallah and Tosh nallah, which join the
river Parbati, are the major tributaries of Parbati River. The total catchment area of Parbati
River at Pulga Dam site is 1155 sq km. This catchment has a large number of small and big
glaciers. Over 84% of the catchment of Parbati Stage II project i.e. about 971 sq km is
permanently snow covered. Further 45% of the catchment area is above an altitude of 5000 m
above Mean Sea Level. The entire river catchment is located in the Himalayan mountain ranges.
The catchment area is sparsely populated because of snowing condition, steeply sloping
mountain ranges, remote location and inaccessibility.

10. Parbati project stage-II
Parbati Hydroelectric Project (Stage-II) is a run-of-the-river scheme proposed to harness hydro
potential of the lower reaches of the river Parbati. The river is proposed to be diverted with a
Concrete Gravity Dam at Village Pulga in Parbati valley through 31.52 Km long Head Race
Tunnel and the Power House shall be located at village Suind in Sainj valley. Thus gross head
of 863 m between Pulga and Suind will be utilized for generating 800MW power. The diverted
discharge of the river Parbati has been further augmented by diverting the discharge of various
nallahs falling along the HRT alignment.
Four catchment of project are:
1. Parbati River
2. Jigrai nallah
3. Hurla nallah
4. Jiva nallah
Basic layout Plan PHEP-II

11. Parbati Hydroelectric project
Stage-II, sainj
(Himachal Pradesh)

12. Features:
Location Distt. Kullu, Himachal pradesh
Power house On River sainj, right bank of village suind.
Location of dam Diversion type dam on river Parbati at pulga village
Capacity 4 ×200 MW
Design Energy 3108.66 MU(90% dependable year)
Beneficiary states H.P., Delhi, J&K, Punjab, Haryana, Rajasthan, U.P., and
union territory of Chandigarh.
Project cost Rs. 3919.59 crore
Date of commercial operation December 2018 (Now Anticipated)
Technical Features:
 83.7 m high concrete Gravity dam.
 130 m high, 17m Dia Orifice type surge shaft.
 6 m dia 31.52 km long Head race tunnel.
 2 Pressure shafts each of 3.5 m dia. and 2132 (right) & 2149 (left) m length.
 4 nos. Tail Race Channels 60m long 5 m x 4.5 m each.
 Surface power house containing 4 Pelton Turbine Generating units of 200 MW each.
 400 KV GIS Surface Switchyard with 2 outgoing 400 KV feeders.

13. Typical Layout:
Head race Tunnel
Here water bifurcate from
surge shaft
Inclined pressure shaft at 300
Horizontal pressure shaft Penstock
Main inlet valve (MIV)
Surge shaft
Butterfly valve
Dam

14. Major components of PHEP-II:
1. Dam and its associated parts
2. Water conducting system
3. Power house
1.Dam and its associated parts:
 For PHEP- II we are using Diversion type dam situated near village pulga.
 A diversion dam is usually of low height and has a small storage reservoir on its
upstream. The diversion dam is a sort of storage weir which also diverts water and has a
small storage. Here height of our dam is about 83.7m
 PHEP- II is Run-of-River type of Hydroelectric scheme that uses small dam construction
that’s why it’s most preferred type for hydroelectricity generation.
 Barrage is little bit differ from dam on basis of orientation of gate and barrage is
primarily meant for diversion purpose but can be used for storage of water also.
 A diversion tunnel is either a permanent or temporary tunnel built essentially for the
purpose of diverting the water like in case of dam construction, flooding situation, or to
supply the water to some water scarcity regions.
 A cofferdam is basically used for construction of bridge piers and other support structures
built within water. They are typically dismantled after work is completed within water.
 Spillways are structures constructed to provide safe release of flood waters from a dam to
downstream in the river on which dam is constructed. In this situation excess water spills
from the top of dam.
 Silt flushing tunnel is provided in order to remove silt from the conducting water so, as to
prevent the destruction of Turbine.
2. Water conducting system:
 From layout we can see that HRT, Surge shaft, Valve house, Pressure shaft, Penstock
together constitutes the water conducting system.
 Head race tunne l(HRT) is water conducting unit that runs from reservoir to power
station. Total HRT is of 31.52 km having 6m diameter.
 Surge shaft is provided with gates to stop flow of water to penstock if repairs to be done
in penstock or inlet valve. We have used orifice type of surge shaft having diameter of
17m. It bifurcate the water channel, That leads to form a network of 4 power generator.
 The Penstock protection valves are provided after the surge shaft to facilitate
maintenance of the penstocks. The valves are of butterfly type of 3.5m diameter. The BF
valve are operated hydraulically with provision of pressure accumulators in case of power
failure.

15.  Pressure shaft are underground circular openings like tunnels in which fully pressurized
flow of water is expected like in pipes. They are alike HRT with smaller diameter and
greater slopes. We have used two pressure shaft having 3.5m diameter of different length
and orientation, one is of length 1.542km at an angle of 30 degree and other one of length
592m and nearly horizontal.
 After pressure shaft water is again bifurcate in two penstocks of each having length of
151.12m. So, Penstock is connecting surge shaft to Main inlet valve (MIV).
3. Power house:
PHEP- II is surface type of Power House.
Power house consist of-
a).Main inlet valve
b).Generation system
c).Transmission system.
a).Main inlet valve:
The 1800 mm diameter main Inlet valve of spherical type that have been provided for shutting off
the pressure water supply from the penstock to the turbine distributor. The valve is designed to open
under balanced condition and close against the full turbine flow. The valve is suitably anchored to
the foundation so as to be free from vibration and other abnormality.
Specifications of MIV:
 Inside diameter: 1800mm
 Length of valve body: 2400mm
 Total number of units: 4
 Valve: Spherical type(more than 200m head)
 Weight of valve without counter weight: 100 tons
 Oil pressure units: 2
 Valve operated oil pressure: 60kg/cm2
(Rated)
 Operating torque to close the valve at Rated O/P: 1500KNm
Components of MIV:
 Spherical / Butterfly valve
 By pass valve
 Oil Pumping unit
Spherical valve: It consist of plate which is in line with the flow of water when is in open
condition and in totally vertical direction when in closed position.

16. By Pass Valve: The oil operated 70 mm diameter by pass valve is provided for balancing
pressure across the spherical valve before opening. When service seal is engaged, balance
pressure of 80% is required across spherical valve before disengaging service seal and rotation
of valve from closed position to open position. The inlet flange of bypass valve is connected to
the spherical valve and the outlet is connected to the outlet pipe. The valve consists of a cast
steel body, a stainless steel needle with operating rod and stainless saddle for sealing and
operated servomotor. Metal to metal sealing has been provided to obtain leak proof seal when
the valve is closed. Two limit switches with the cam arrangement are provided for obtaining
and closing indication. A manually operated locking device has been provided to lock the
bypass valve at any opening from fully open to fully close.
Oil pumping unit: The system consists of a pressure pumping set and pressure receiver. Each
unit is provided with its own pumping set & has been designed to cater the oil requirement of
MIV & MIV servomotor.
Pressure Receiver:
Is used to meet all the requirements of the system and it works as reservoir of servomotor to
open or close. The oil in this receiver is always kept under pressure with the help of compressed
air within very close range of operation. Normally the air-oil ratio is maintained as 2:1 at
normal working pressure.

17. Spherical valve Oil pressure unit
MIV complete assembly Servomotor
By pass valve Pressure Receiver
MIV and its Associate Parts

18. b).Power Generation system:
I). Turbine (Mechanical based)
II). Generator (Electrical)
I). Turbine:
A turbine is a rotary mechanical device that extracts energy from fluid flow and converts it into a
useful work. It is a turbo machine with at least one moving part called a rotor assembly, which is a
shaft or drum with blades attached. Moving fluids acts on the blades so that they move and impart
rotational energy to the rotor.
Types of turbine:-
1. Impulse turbine - Impulse turbines change the direction of flow of a high velocity fluid or gas
jet. The resulting impulse spins the turbine. Example: Pelton turbines
2. Reaction turbine - These turbines develop torque by reacting to the gas or fluids pressure or
mass. The pressure of the gas or fluid changes as it passes through the turbine rotor blade. Example:
Francis turbines
The turbine used in the power house is Pelton turbine. These turbines are suitable for power
extraction when the water energy is available at high head and low flow rate. It is an efficient
machine and consists of a large circular discs or wheels which are spaced uniformly around its
periphery.
Nozzles direct forceful, high speed streams of water against the buckets. As the water jet impinges
against the bucket blades, the water impulse energy exerts torque on the bucket and the wheel,
hence spinning the wheel.
Specification of power house turbine:
 Type: Pelton turbines (Vertical axis)
 No. of bucket: 22 Nos.
 Net design head: 790m
 Turbine output(90% nozzle opening): 204MW
 Continuous overload output: 233.3MW
 Rated speed at net head: 375RPM
 Runway speed: 633RPM
 Rated discharge: 27.3m3
/ sec
 Turbine Runner diameter: 3080mm
 Wt. of turbine shaft: 27 ton
 Distributor: 6 Nos.
 Break Jet: 2 No. with 100mm dia.
 Direction of rotation : clockwise when seen from above
 Max. Output at max. Head: 10% overload
Turbine consists of runner, distributor, turbine housing, main shaft, guide bearing, nozzle assembly,
deflector servomotor and break jet. Runner has 22 buckets. Water is forced onto the runner through
6 nozzles made of mild steel.

19. Nozzle with 6 jets and 2 breakjets Deflector servomotor and main shaft
Nozzle Runner with 22 buckets

20. Turbine housing Distributor (6 inlets)
Pelton Turbine and its associate parts
Guide Bearing
Deflector

21. II). Generator:
In electricity generation, a generator is a device that converts mechanical energy to electrical
energy for use in an external circuit. The source of mechanical energy may vary widely from a
hand crank to an internal combustion engine. Generators provide nearly all of the power for
electric power grids.
Basic Working:
The generator creates electricity by a series of fine wire windings inside a magnetic field, called
an armature. As the armature is spun inside this magnetic field by the generator's motor, current and
voltage gets generated in those windings of wire and electricity is transferred. That current and
voltage will be directly proportional to the speed that the armature spins and to the strength of the
magnetic field. Each complete revolution, one complete cycle of alternating current (AC) is
developed. This is called a rotating armature.
In a stationary armature, the magnetic field rotates around the armature. The advantage of having a
stationary armature winding is that the generated voltage can be connected directly to the load.
Types of Synchronous Generators (alternator):
There are two main types of alternator categorized according to their design. They are-
1). Salient pole type - It is used as low and medium speed alternator. It has a large number of
projecting poles having their cores bolted or dovetailed onto a heavy magnetic wheel of cast iron
or steel of good magnetic quality. Such generators are characterized by their large diameters and
short axial lengths. These are mainly used in low speed turbines such as hydel power plant.
2). Smooth cylindrical type - It is used for steam turbine driven alternator. The rotor of this
generator rotates at very high speed. The rotor consists of a smooth solid forged steel cylinder
having a number of slots milled out at intervals along the outer periphery for accommodation of
field coils. These rotors are designed mostly for 2 pole or 4 pole turbo generator running at 3000
rpm or 1500 rpm respectively.
The generator described in this specification is of vertical shaft, salient pole, and suspended type
with Upper guide bearing and thrust bearing combined in the Upper Guide Bracket above the
rotor. The generator also has another guide bearing positioned below the rotor. HS lubrication
systems for injection of oil to the thrust bearing pads are provided for use during starting and
stopping of the machine. The bearings are self-lubricated type and immersed in oil bath in which
plug-in type oil coolers are provided. The turbine has its own guide bearing making a total Three
guide bearings for the complete unit. The generator collector rings and speed signal generator are
located at the top. The generator excitation is provided by separate static excitation equipment.

22. Specification of generator at power house
 Type: Suspension
 Rating(at 0.9 lagging p.f.): 222.22MVA/200MW
 Generating Voltage: 13.8kV
 Generating Frequency: 50Hz
 Rated Speed: 375RPM
 Runway speed: 633RPM
 Direction of rotation: Clockwise (viewed from top)
 Efficiency (at rated frequency, voltage and p.f.): 98.77%
 Field current: 1400A D.C.
 Field Voltage: 265V D.C.
 No. and type of collector ring: 34, Carbon
 Insulation: Class F
 Weight of rotating parts with shaft: 350 Tons
 Diameter of Rotor: 4792mm
 Air gap b/w rotor and stator: 35mm
 Air braking cylinders: 8 Nos.
 Cooling: Water cooled.
Components of a generator:
 Stator(contains armature winding)
 Rotor (contains field winding)
 Shaft
 Excitation system
Stator:
It is the stationary part of the machine and is built up of sheet-steel laminations having slots on its
inner periphery. A 3-phase winding is placed in these slots and serves as the armature winding of
the alternator. The armature winding is always connected in star and the neutral is connected to
ground.
The stator is enclosed in a stator frame which acts as the housing for the stator core and winding.
The frame provides it a rigid structure and also acts as a protective casing for the generator.
Rotor:
The rotor carries a field winding which is supplied with direct current through two slip rings by a
separate D.C. source. This D.C. source (called exciter) is generally a small D.C. shunt or compound
generator mounted on the shaft of the alternator.
Rotor core is fixed on the rotor frame called spider and is made up of mild steel laminated sheets
stacked together. These sheets are thicker than the stator core sheets having a thickness of 2.5mm
weighing nearly 11.5kgs. The stator core contains rectangular slots on its outer periphery to hold
the rotor poles.

23. The salient pole would cause an excessive windage loss if driven at high speed and would tend to
produce noise. Hence to produce 50 Hz frequency the rotors are rotated at slow speeds (120-
750RPM) and are provided with large number of poles (8-50 poles). In this case the rotor has 16
poles and rotates at 375 RPM.
Generator

24. C).Power Transmission system:
I).Transformer:
A transformer is an electrical device that transfers energy between two or more circuits through
electromagnetic induction. It is a static device used either for raising or lowering the voltage of
an a.c. supply with a corresponding decrease or increase in current. It essentially consists of two
windings, the primary and secondary, wound on a common laminated magnetic core.
The winding connected to the a.c. source is called primary winding (or primary) and the one
connected to load is called secondary winding (or secondary). The alternating voltage V1 whose
magnitude is to be changed is applied to the primary. Depending upon the number of turns of
the primary (N1) and secondary (N2), an alternating e.m.f. E2 is induced in the secondary. This
induced e.m.f. E2 in the secondary causes a secondary current I2. Consequently, terminal
voltage V2 will appear across the load. If V2 > V1, it is called a step up-transformer. On the
other hand, if V2 < V1, it is called a step-down transformer.
Transformers used at power house
 Generator Step up transformer
 Neutral grounding transformer
 Unit Auxiliary transformer
 Service station transformer
 Tap off transformer
 Current transformer
 Potential transformer
Generator step up Transformer:
There are total 14 step-up power transformers available at the power house, of which 12 are
continuously operated and 2 are kept in spare. Each 3-phase generator is connected to 3 single
phase transformers. The low voltage sides of the transformers are connected in delta and each
transformer is fed with 13.8kV. The high voltage sides of the transformers are connected in star
with a neutral and the three phase output voltage is 400kV.

25. Specifications:
 Type: Single phase shell type
 Number of transformer: 12+2 (spare)
 Rated capacity of transformer: 82 MVA
 Rated voltage (L.V. side): 15 kV line
 Applied voltage (L.V. side): 13.8 kV
 Rated voltage (H.V. side): 440 kV line
 Number of tapings:
 Rotations required for tap change: 33 rotations
 Current L.V. side: 5942.03 A
 Voltage and current rating at H.V. Side at different tapings:
 Tap 1: 441/√3 kV, 322.06 A
 Tap 2: 430.5/√3 kV, 329.91 A
 Tap 3: 420/√3 kV, 338.16 A
 Tap 4: 409.5/√3 kV, 346.83 A
 Tap 5: 399/√3 kV, 355.96 A
 Vector group: Y n d11
 Voltage adjustment: 7.5 to -2.5%
 Cooling: Oil Forced Water Forced
 Oil volume: 28500 litre
Transformer

26. II). GIS :
Gas insulated system (GIS) is a kind of metal enclosed switchgear. In this type of switchgear,
all the necessary components of switchgear can be assembled in very limited space. That
means, all the equipments of the electrical switchgear are enclosed by gas tight metal enclosure
and SF6 gas is used as insulation between live parts of the equipments. It contains two bus duct
for transmit power to external. if one bus duct do not work so bypass second duct is used to
transmit.
Gas Insulated Switch gear(GIS)
III). Pothead yard:
Pothead yard consist of following equipment
1). Wave trap
2). CVT (Capacitive Voltage Transformer)
3). Lightning arrestor

27. Pothead yard

28. Hydro Technology FAQ’s:
 How much is the world’s electricity supplied by Hydroelectric Power Plants?
± 2700 TWH is generated every year. Hydropower supplies at least 50% of electricity production in 66
countries and at least 90% in 24 countries.
 What are the different types of turbines used in Hydroelectric Power Plants?
There are basically four types of power plants: -
 Pelton turbines - It is impulse turbine which is normally used for more than 250 m of water head.
 Francis - This is a reaction turbine which is used for head varying between 2.5m to 450m
 Kaplan – It is propeller type of plant with adjustable blades which are used for heads varying
between 1.5 m to 70 m
 Propeller – It is used for head between 1.5 to 30 m
 Tubular – This is used for low and medium height projects. Normally for head less than 15 m.
 What are the major components of a Hydroelectric Power Plant?
The major components of a Hydroelectric Power Plant are:-
 Dam/Barrage
Head works i.e. power intake, head regulator and desilting chambers etc.
 Head race tunnels/channels
 Surge shaft/surge chambers
 Pressure shaft/Penstock
 Underground and surface power house
 Tailrace channel or tailrace tunnel.
 What is the classification of Hydro Projects based on Installed Capacity?
Micro: Upto100 KW
Mini: 101KW to 2 MW
Small: 2 MW to 25 MW
Mega:
Hydro projects with installed capacity >= 500 MW
Thermal Projects with installed capacity >=1500 MW
 Which is the largest Hydropower station in the world?
Three Gorges project in China on Yang-Yang river is the largest power station in the world having
installed capacity of around 22,500 MW.
 How does cost of generation from Hydropower Plant compare with other sources of
electricity?
The hydro power generation is highly capital-intensive mode of electricity generation but being
renewable source of energy with no consumables involved; there is very little recurring cost and hence
no high long term expenditure. It is cheaper as compared to electricity generated from coal and gas
fired plants. It also reduces the financial losses due to frequency fluctuations and it is more reliable as it
is inflation free due to not usage of fossil fuel.
 Why hydropower is called renewable source of energy?

29. Hydropower is called renewable source of energy because it uses and not consumes the water for
generation of electricity, and the hydropower leaves this vital resource available for other uses
 Which is the oldest Hydropower Plant in India?
The oldest Hydropower power plant is in Darjeeling District in West Bengal. It’s installed capacity is
130KW and was commissioned in the year 1897.
 What is the estimated total Hydropower potential of India?
The hydro power potential of India is around 1,48,701 MW and at 60% load factor, it can meet the
demand of around 84,000 MW.
 How much of the total Hydro power potential has been exploited so far in India?
Around 19.9% of Hydropower potential has been exploited in India.
 What are the different types of dams?
Different types of dams are conventional concrete dam, Roller compacted concrete dam, rock fill dam,
Concrete Faced Rock fill Dam (CFRD), Earth fill dam, arch dam, barrages etc.
 Why the unit sizes of hydro generating machines are not standardized as in case of
thermal power plants?
Since the size of hydro generating machines are based on availability of water in river and the water
head available at a particular project site, the size of the machines keeps varying from location to
location and river to river. The sizes are also based on logistics and variation of water in river during the
year.
 What is the record completion period of a Hydro Power Station in India of more than
100MW?
Chamera – II HE Project (300 MW) in Distt. Chamba, HP. has been completed in a record period is
Four & Half years .
 Which Hydro Station has been completed recently which has the lowest tariff rate?
Teesta HE Project-V (510 MW) in the State of Sikkim was completed in April, 2008. The sale rate of
this project is @Rs.1.53 / Kwh(approx.) to beneficiary states of Eastern Region as per the petition filed
in Central Electricity Regulatory Commission.(For FY 2008-09).
 What are the different types of Hydro Schemes?
Different types of Hydro Schemes are :
 Purely Run - of - River Power Station.
 Storage type Power Station.
 Run – of – River Stations with Pondage.

30.  Which is the largest Operating Hydro Power Station in the World?
The world’s Largest Hydro Electric Power Station is ITAIPU with installed capacity of 12600 MW and a
reliable output of 75,000 MU in a year. It is located at the Border of Brazil and Paraguay.
 What are the major reasons for balancing Hydro-thermal mix?
Seasonal load curves of our regional grids match with the pattern of hydro power generation. During
summer/monsoon season when the generation at hydro power plants is high, the load factor of the
system is high due to heavy agricultural load. During winter, the thermal stations operating at base load
and hydro stations working as peak load stations will take care of weather beating loads. Thus the
operational needs of hydro & thermal stations are complimentary and the balanced mix helps in optimal
utilization of the capacity.
 Why Hydropower stations are preferred solution for meeting peak loads in grids?
Due to its unique capabilities of quick starting and closing, hydropower stations are found to be
economical choice to meet peak load in the grid.
 What are approaches to tackle sedimentation problem of reservoir?
The following are some approaches to tackle sedimentation problem of reservoir:-
 Catchment Area Treatment (CAT) for reduction of silt load includes afforestation of the catchment
area and Environmental works such as construction of check dams.
 Effective desilting arrangements for prevention of silt.
 Silt resistant equipments of withstanding the silt.
 Effective operation of the reservoir to minimize silt deposition.
 What are the effects of sedimentation in Hydropower stations?
The major effects of reservoir sedimentation are-
 It reduces the active storage capacity, which may reduce the capability of the reservoir to deliver
the benefits in course of time.
 It makes the flood management in the reservoir more difficult.
 Damages to turbines and other under water parts due to abrasive action of silt.
 Do Hydropower projects cause huge destruction of forests?
Massive afforestation has been undertaken at the commissioned as well as ongoing projects of NHPC.
In eight commissioned projects of NHPC viz. Tanakpur, Chamera-I, Chamera-II, Uri, Rangit,
Dhauliganga, Dul Hasti, Teesta-V and six under construction projects viz., Parbati-II, Parbati-III, TLDP-
III, TLDP-IV, Chamera-III, Sewa-II afforestation has been undertaken over an area of 4333 ha. of
degraded/non forest land, in lieu of diversion of 2734.44 ha of forest land required. In these 14 projects,
against 101781 affected trees, NHPC has planted more than 93 lakh trees under Compensatory
Afforestation.
 Does development of Hydropower project leads to large scale displacement?
In construction of PHEP- II, 37 families has been displaced and about 402 families partially affected
due to this project. While in PHEP- I, 59 families has been displaced and about 279 families partially
affected.

31. Conclusion:
India is endowed with enormous economically exploitable and viable hydro potential assessed
to be about 84044 MW at 60% load factor (148700 MW installed capacity). Total annual
energy potential of 600 billion unit has been accessed and so far only 15% of the potential has
been exploited. Over one billion people in SAARC are amongst the poorest in the world and
lack even the basic social amenities including electricity. Per capita demand of electricity in
Asia is only 1250 KWhr, which is half of the world average. A certain study indicates that the
need of consumption of minimum 1500 KWH of electricity to maintain even marginal standard
of living. Against this, the per capita consumption of electricity in India is only 350 KWH,
which speaks of immediate and urgent need of planning and undertaking accelerated hydro
development in the country. India, with no large known oil and gas reserves, is independent on
indigeneous coal as the main in feed for electricity production. This is leading to depletion of
non-renewable source of energy on one hand and environmental degradation as well. Switching
to clear fuels, wherever available is therefore to be taken on top priority. In India vast potential
exists for Hydro-development from white coal i.e. water. Over the years due to paucity of funds,
the regional power development had led to imbalance in the hydrothermal mix to 25:75 as
against desired ratio of 40:60. It is well known that hydropower can give excellent peaking
support and prevent sub-optimum level of operation of thermal plants i.e. burning expensive oil
off peak hours. As per CEA 15th Electric Power survey, the present peak demand is 63853 MW
and projected peak demand is 95757 MW for the Year 2001-02. The recent R & D innovations
in the field of hydro-dynamics make it possible to derive higher outputs from the existing
hydraulic space in turbines by employing higher specific speed and better efficiency profiles on
one hand and use of better class epoxy insulation on the other which makes it possible to use
higher conductor size in the existing stator slots for higher outputs. The older plants hold
substantial potential of up rating at the time of renovation thereby making up rating proposals
cost effective. Besides enhancement of peaking capacity, there would be extra energy benefit in
the case of run-off-the-river scheme. The other good thing about run-off-the-river scheme is that
it creates lesser impact on the environment and lesser no. of people are distributed in the area.
The regional grids in India suffer from problems of wide frequency and voltage fluctuations,
frequent grid failure, uneconomic operation, problems in evacuation of power etc. Hydropower
can give relief from most of these problems.
It is not only to get the Technical Experience but also to observe management practice and how
to interact with fellow workers.

32. Sources
http://www.nhpcindia.com/about-overview.htm
https://en.wikipedia.org/wiki/NHPC_Limited
https://www.slideshare.net/swati71/nhpc-projectparbati-2-on-store-accounting-finance
https://clipartxtras.com/categories/view/0906eeec25b654a58dd01602d69c77069459eba7/hydroelectr
ic-power-plant-drawing.html