ACKNOWLEDGEMENT

Any project of work cannot be accomplished to one’s satisfaction with proper

guidance and total co-operation of all these involved in this project. I convey

my deep regards to all of them.

I express my sincere thanks to my trainer Mr. Batra for guiding me right from

the inception till the successful completion of my training. I sincerely

acknowledge him for extending their valuable guidance, support for literature,

critical reviews of training and the report and above all the moral support that

had provided to me with all stages of this training.

I would also like to thanks the supporting staff of the HYDRO POWER

STATION for their help throughout the training.

PAGE INDEX

Topic Page No.

1. INTRODUCTION : 1

2. INDIA’S CRITICAL NEED

FOR POWER : 3

2.1 WATER POWER : 3

3. BASIC PRINCIPLE AND

METHODS OF ELECTRIC

GENERATION : 4

3.1 BASIC PRINCIPLE : 4

3.2 TYPICAL HYDRO POWER

STATION : 5

3.3 OUTPUT SYSTEM : 6

4. GENERAL DESCRIPTION : 7

4.1 FUNCTION OF RPS HPS : 7

4.2 COST AND OPERARATIONAL

STATISTICS OF RPS HPS : 8

4.3 FUNCTIONAL IMPORTANCE : 8

4.4 PARAMETRS RELATED TO

RPS HPS : 9

4.5 SELECTION OF SITE : 10

5. MAJOR ELEMENTS : 11

5.1 STORAGE RESERVOIR : 11

5.1.1 DAM : 12

5.1.2 FOREBAY : 12

5.1.3 TRASHBACK : 12

5.1.4 SPILWAY : 12

5.1.5 PENSTOCK : 12

5.1.6 TAIL RACE : 13

5.1.7 DRAFT TUBES : 13

5.1.8 HYDRAULIC TURBINES : 13

5.2 TURBINE CLASSIFICATION : 15

5.2.1 IMPULSE TURBINE : 15

5.2.2 REACTION TURBINE : 15

5.2.3 TURBINE SPECIFICATIONS : 17

5.2.4 DESIGN AND MANUFACTURE OF TURBINE : 18

5.2.5 LEVEL OF EQUIPMENTS : 19

5.2.6 MOUNTED ON UNIT CONTROL BOARD : 20

6. POWER TRANSFORMER : 21

6.1 TRANSFORMER RATING : 21

6.2 GOVERNING SYSTEM : 21

6.3 ELECTRICAL EQUIPMENT : 22

6.3.1 MAIN COMPONENTS OF GENERATOR : 22

7. ELECTRICITY GENERATION : 24

7.1 HYDRAULIC POWER : 25

7.2 INDUSTRIAL HYDROELECTRIC

PLANTS : 28

7.3 SMALL SCALE HYDROELECTRIC

PLANTS : 28

7.4 ADVANTAGES : 29

7.5 ECONOMICS : 29

7.6 GREEN HOUSE GAS EMISSIONS : 29

7.7 RELATED ACTIVITIES : 30

7.8 DISADVANTAGES : 30

7.9 HYDROELECTRIC POWER STATIONS

AND ENVIRONMENT : 30

7.10 COPARISONS WITH OTHER METHODS

OF POWER GENERATION : 31

8. ELECTRICAL SYSTEM : 33

8.1 MAJOR ELECTRICAL EQUIPMENTS

WITH THEIR SPECIFICATION : 33

8.1.1 ALTERNATOR : 33

8.1.2 ALTERNATOR RATING : 33

8.2 CURRENT TRANSFORMER : 34

8.2.1 CURRENT TRANSFORMER RATING : 35

8.3 POTENTIAL TRANSFORMER : 36

8.4 CIRCUIT BREAKER : 36

8.4.1 THE TYPES OF CIRCUIT BREAKER : 36

9. SF6 GAS CIRCUIT BREAKER : 38

9.1 GENERAL INFORMATION : 38

9.2 OPERATION OF CIRCUIT BREAKER : 40

9.3 AUXILIARY SWITCH : 40

9.4 RAPID AUTOMATIC RECLOSING : 41

9.5 COMMISSIONING : 41

10. FIREPROTECTION SYSTEM : 44

10.1 FIRE PROTECTION SYSTEM : 44

10.1.1 SMOKE DETECTION SYSTEM : 44

10.1.2 MULTIFIRE SYSTEM : 44

10.2 ISOLATOR : 45

10.3 EARTHING SWITCH : 45

TABLE INDEX

Table Page No.

4.1 Parameters related to RPS HPS : 9

5.1 Francis hydraulic turbine : 17

5.2 Design and manufacture of turbines : 18

5.3 Level of equipment : 19

6.1 Transformer rating : 21

8.1 Alternator Rating : 33

8.2 Current Transformer Rating : 35

(Victrans Engineers)

8.3 Current Transformer Rating : 35

(General electric)

FIGURE INDEX

Figure Page no.

3.1 Hydroelectric dam : 5

5.1 Inside a hydroelectric plant : 11

5.2 Impulse turbine v/s Reaction turbine : 16

5.3 Francis turbine : 17

7.1 Hydroelectric power : 24

7.2 Generator : 25

9.1 SF6 circuit breaker : 39

9.2 Cross section of SF6 circuit breaker : 42

ABSTRACT

Practical knowledge is very important in every field one must be familiar with

the problem related to that field, so that he may solve them and become a

successful person.

After the successful completion of study an engineer has to serve a industry,

may be public or sector or self owned.

To be a good engineer, one must be aware of industrial environment, working

in industry, labor problem etc. so as to tackle technical problems successfully.

To bridge the gap between theory and practice, our engineering curriculum

provides training course of 45 days.

I have undergone my 45 days training at Rana Pratap Sagar Hydro Power

Station, Rawatbhata. This report has been prepared on the basis of

knowledge acquired by me during the period at the power station.

CHAPTER 1

INTRODUCTION

In the second stage CHAMBAL RIVER VALLEY DEVELOPMENT

PROJECT a masonry dam at RAWATBHATA “RANA PRATAP SAGAR

DAM” in district Chittorgarh. The dam and Hydro Power Plant constructed

in the second stage of the Chambal project and was named “RANA

PRATAP SAGAR DAM and Hydro Power Plant” in the memory and

honor of the great warrior of Mewar, the legendary Maharana Pratap.

The Rana Pratap Sagar Dam is the part of “Chambal Project”. There are

three hydroelectric power stations: First at Gandhi Sagar , Second at

Rawatbhata Rana Pratap Sagar and third at Jawahar Sagar.

RPS is balancing reservoir between G.S. upstream and J.S. downstream.

This is followed by the Kota Barrage and water diverted from it is

extensively used for irrigation purpose in parts of Rajasthan and Madhya

Pradesh.

The RPS dam was constructed between 1965 to 1968 and dedicated to the

nation by former Prime Minister Late Smt. Indira Gandhi .

There are four dams in cascade on Chambal River in the stretch of 70 kms

as riverbed drops by about 120 meters between Gandhi Sagar and Kota.

Kotan Thermal Power Station of 1060MW(e) is located at upsteam of Kota

barrage.

This dam is used for both irrigation and generation of electricity. The total

dam length is about 1km and 25 feet wide.

RPS hydro power plant consists of four units of each 43 MW. This plant

serves electricity to Kota, Bhilwara and Gandhi Sagar. The generated

voltages are 11KV and transmission voltage is 132 KV. AT the discharge

water side a tunnel is constructed for raising the effective head of water.

RPS consists of four vertical type generator build specification no.

GS/2/1962 CANADIAN GENERAL ELECTRIC EN1607080 parts list

117L456. The direct connected exciters are build by CANADIAN

GENERAL ELECTRIC EN101213. These machines are designed in

accordance with ASA standard British Standard.

CHAPTER 2

INDIA’S CRITICAL NEED FOR POWER

Severe power shortage is one of the greatest obstacles to India’s

development. Over 40 percent of the country’s people –most living in the

rural areas—do not have access to electricity and one third of Indian

business constraints.

India’s energy shortfall of 10 percent (rising to 13.5 percent at peak

demand) also works to keep the poor entrenched in poverty. Power

shortages and disruptions prevent framers from improving their agricultural

incomes, deprive children of opportunities to study and adversely affect the

health of families in India’s tropical climate.

Poor electricity supply thus stifles economic growth by increasing the costs

of doing business in India, reducing productivity and hammering the

development of industry and commerce which are the major creators of

employment in the country.

2.1 WATER POWER

Water is the cheapest source of power. It served as the source of power to

of power to our civilizations in its earlier days in the form of water wheels.

Faraday’s discovery of electricity has proved to be very useful to use water

for producing electric power. A hydroelectric power plant is aimed at

harnessing power water flowing under pressure.

CHAPTER 3

BASIC PRINCIPLE AND METHODS OF

ELECTRIC GENERATION

3.1 BASIC PRINCIPLE

When a closed coil is rotated rapidly in a strong magnetic field, the number

of magnetic flux lines passing the coil changes continuously. Hence an

EMF is induced in the coil and the current flows in it. In fact the

mechanical energy expended in rotating the coil appears as electrical

energy ( current) in the coil.

There are different types of methods or systems by which electricity is

produced such as:

Hydel electric power station- water turbine

Thermal power station-steam turbine

Nuclear power station-steam turbine

Gas power station-gas turbine

Neptha of lignite base power station

Solar power station

Wind power station

Fig-3.1 Hydroelectric dam

3.2 TYPICAL HYDRO POWER INSTALLATION

As shown schematically in fig 3.1, the hydraulic components of a

hydropower installation consist of an intake, penstock, guide vanes or

distributor, turbine and draft tube. Trash racks are commonly provided to

prevent ingestion of debris into the turbine. Intake usually required some

type of shape transition to match the passage way to the turbine and also

incorporate a gate or some other means of stopping the flow in case of an

emergency or for turbine maintenance. Some types of turbines are set in an

open flume; others are attached to a close conduit penstock.

3.3 OUTPUT SYSTEM

Electricity is distributed in our country by a big and vast grid system. The

total grid of India is divided in to the five regions and distributing the

power through different load dispatch centers.

Following are the regional grids-

Northern regional grid

Western regional grid

Southern regional grid

Eastern regional grid

North-East regional grid

Rajasthan is connected to the Northern regional grid where as Madhya

Pradesh is connected to the western regional grid.

Northern region is the largest region among the five regions of the country

in terms of geographical area as well as the number of consumption.

Following is the balance sheet of generation and load with their sources and

demands-

Generation Demands

Hydel 32%

Thermal 55%

Gas 10%

Nuclear 3%

Agriculture 40%

Industrial 38%

Domestic 22%

Table 3.1

CHAPTER 4

GENERAL DESCRIPTION

At RPS HEPS, vertical turbine rotates at 125 rpm by the water velocity.

Generator is directly coupled with the turbine, giving output of 43MW(e) at

11KV voltage 50 Hz frequency. Output voltage is step up to 132 KV by the

transformer and transmitting to the Northern grid through several transmission

lines which are going to Bhilwara (2 No), Jawahar sagar (1No) and Gandhi

sagar (2No).

The plant is operated and controlled from a centralized control room which is

having all the information and parameters regarding different system of the

plant and its equipments.

Alarm systems are provide in C/R to take appropriate actions in case of any

abnormal operation and taking the action accordingly.

A small diesel generator set of 300KW capacity providing the emergency

power supply to their plant equipments and being used for starting the units.

The water after doing its work on the turbine, discharged in a fore bay form

where it goes to the downstream of Chambal River through a big tunnel.

4.1 FUNCTION OF RANA PRATAPSAGAR HYDRO

ELECTRIC POWER STATION

To produce electricity as an active power of 4*43 MW(e) and

supplying it to Rajasthan through 7 lines of 132 kv.

Operates synchronous condenser for better voltage regulations of the

grids as and when required.

To provide dedicated power supply to the nearest Nuclear power

station on priority basis whenever there is a problem in Northern grid

for starting of the plant and for maintaining auxiliary power supply of

their plant in order to meet the safety norms of Nuclear Stations

To supply first power to the grid by the self-start in case of total

collapsing of northern grid.

4.2 COST AND OPERATIONAL STATISTICS OF RPS HEPS

The total cost of RPS dam and power station was Rs 40.65crores out of

which Rs 14.74crores was spent for power station. All the equipments of

power station were imported from Canada under Colombo Yojana.

There are four units of 43 MW(e) each. First starting date of these units are-

Unit Capacity Date of generation

First 43MW 03.02.1968

Second 43MW 26.06.1968

Third 43MW 28.12.1969

Fourth 43MW 24.05.1969

4.3 FUNCTIONAL IMPORTANCE

This plant plays a most crucial role when there is a disturbance in the Northern

grid. When the grid fails this power station provides the startup power for

restoring the Northern grid. It also plays a major role in the routine times by

providing stability to the machines of Rawatbhata Atomic Power Plant

contributing to the stability of the grid.

4.4 PARAMETERS RELATED TO RPS HPS, RAWATBHATA

S.no. PARTICULARS

1 Location:

-Attitude

-Longitude

-Altitude

24°-53° North

75°-35°East

354 meter above MSL

2 Water Storage Capacity 9600Sq.Mile

3 Catchment Area 76.55Sq.Mile

4 Reservoir Capacity 76.55Lakh acr. Ft

5 Max. reservoir level 1162Ft.

6 Min. Draw down level 1128.5Ft

7 Full reservoir level 1157.5Ft

8 Generating capacity 4X43 MW

9 Diameter of Penstock 20Ft.

10 Maximum Head 189Ft.

11 Minimum Head 152Ft.

12 Crest Gate 17;60X28 Ft.

13 Sluce Gate 4;9X11 Ft.

14 Length of tunnel 4840 Ft.

15 Diameter of tunnel 40 Ft.

16 Maximum Discharge 14000cusecs

17 Length of Top Portion Of Dam 3750 Ft.

18 Maximum Height Of Dam 177 Ft.

19 Generator output 11KV

20 Output Lines Voltage 132KV

21 Submerged Area 198 Esq.

Table 4.1

4.5 SELECTION OF SITE

Selection of suitable site for hydroelectric plant. If a good system of natural

storage lakes at high altitudes and with catchment can be located.

The following factors should be considered.

Such power stations are build where there is adequate water be build at

good head i.e. huge quality of water is following across a given point.

Since storage of water in a suitable reservoir at 5 a height or building of

Dam across the river is essential in order to have continuous & terminal

supply during the dry season. Therefore, convenient accommodation for

erection of a Dam or reservoir must be available.

The reservoir must have a large catchment area.

The land should be cheap in cost & rocky in order to withstand the

weight of large building & heavy machinery.

Adequate transportation facilities must be available or there should be

possibility the same .So that the necessary equipment & machinery

could be easily transported.

There should be possibility of stream diversion, during period of

construction.

CHAPTER 5

MAJOR ELEMENTS

FIG:5.1: INSIDE A HYDRO-ELECTRIC PLANT

5.1 STORAGE RESERVOIR

Its purpose is to store water during excess flow periods and supply the same

during lean flow periods. Thus it helps in supplying water to the turbines

according to load of power plant. Live storage i.e. 1.27 MAFT, the full

reservoir levels is 1162 feet.

5.1.1 DAM

The function of dam is not only to raise the water surface of the stream but

also to create an artificial head and to provide the poundage, storage or the

facility of diversion into conduits. A dam is the most expensive & important

part of a hydro-project . this dam’s total length is about 1 Km 25 feet wide and

total height of dam is 177 feet.

5.1.2 FOREBAY

A for bay may be considered as an enlarged body of water just above the

intake to store water temporarily to meet the hourly load fluctuations.

5.1.3 TRASHRACK

It is provided for preventing the debris form getting entry into the intakes from

the fore bay. Manual cleaning or mechanical cleaning is used to remove the

debris from trash rack. Trash rack is made up of steel bars and it is placed

across the intake to prevent the debris form going into the intake.

5.1.4 SPILWAY

This is constructed to act as safety valve. It discharges the overflow water to

the down streamside when the reservoir is full. A condition mainly arises

during floods periods. These are generally constructed of concrete and

provided with water discharge opening shut off by gates. There are 17 gates

used for discharge the overflow water. The size of each gate is 60X28 Feet.

5.1.5 PENSTOCK

It is closed conduct, which connected the fore bay or surge tank to the scroll

case of turbine. In case of medium heads power plants(like R.P.S)such unit is

usually provided with its own penstock with its own penstock. Penstock is

build of steel. The typical diameter of penstock is 20 feet.

5.1.6 TAIL RACE

The water after having done its useful worked in the turbine is discharged to

the tailrace, which may lead it to the same stream or to another one. The water

is discharge through a tunnel. The tunnel is raised the effective head of water

level. The tunnel length is 4810 feet and average discharge through tunnel is

14000 cufeet/sec.

5.1.7 DRAFT TUBES

An airtight diverging with cross-sectional area increasing along its length. It is

an integral part of turbine. The inlet of draft tube is connected to the turbine

and outlet is submerged deep into tailrace. The draft tube makes the turbine

capable of utilizing kinetic energy of the exit water. It also decreases the

pressure at the runner exit to a value less than atmospheric pressure hence the

working head gets increased.

5.1.8 HYDRAULIC TURBINE

A hydraulic turbine is a mechanical device that converts the potential energy

associated with a difference in water elevation head into useful work. Modern

hydraulic turbines are the result of many years of gradual development.

Economic incentives has resulted in the development of very large units

(exceeding 800 MW in capacity) with efficiencies that are sometimes in excess

of 95%.

The emphasis on the design and manufacture of very large turbines is shifting

to the production of smaller units, especially in developed nations, where

much of the potential for developing large-base load plants has been realized.

At the same time, the escalation in the cost of energy has made many smaller.

Sites economically feasible and has greatly expanded the market for smaller

turbines. The increased value of energy also justifies the cost of refurbishment

and increasing the capacity of older facilities.

Thus, a new market area is developing for updating older turbines turbines

with modern replacement runners having higher efficiency and greater

capacity.

In the hydro electric power plants water turbine are used as prime movers and

their functions is to convert the kinetic energy of water into mechanical

energy, which is further utilized to drive the alternators generate electrical

energy.

The RPS hydroelectric power plant is low head plant so “ FRANCIS

TURBINE”

is used. It is a reactor turbine and is suitable for low and medium head power

plant. Such turbines develop power partly due to velocity of water and partly

due to difference in pressure acting on the front and back of the runner

buckets.

Such a turbine essentially consists of “guide apparatus”. Consisting of an outer

ring of stationary blades are fixed to the casing of the turbine and an inner ring

consisting of rotating blades forming a runner. Number of blunders in a glide

over the blades with a small and fairly constant velocity and exerts a pressure,

varying form maximum at the top to a small value at the bottom. The water

flows radically inwards and changes to a downward direction while passing

through the runner.

As the water passes over the rotating blades of the runner, both pressure as a

velocity of water are reduced causing a reaction force during the turbine. After

doing work, water is discharged to the tailrace through a closed tube of

increasing cross section called the draft tube.

The guide blades of the turbine are adjustable about the hinged point with the

help of governing mechanism but don’t rotate with the runner. The guide

blades arranged in the casing around the runner, which give proper direction to

water jets in such a way that the jet don’t strike the runner vanes in opposite

direction.

5.2 TURBINE CLASSIFICATION

There are two types of turbines, denoted as impulse and reaction. In an

impulse turbine, the available head is converted to kinetic energy before

entering the runner, the power available is extracted from the flow at

approximately atmospheric pressure. In a reaction turbine, the runner is

completely submerged head in the inlet to the turbine runner is typically less

than 50% of the total head available.

5.2.1 IMPULSE TURBINES

Modern impulse units are generally of the pelton type and are restricted to

relatively high head applications. One or more jets of water impinge on a

wheel containing many curved brackets.

5.2.2 REACTION TURBINES

Reaction turbines are classified according to the variation in the flow direction

through the runner. In radial and mixed flow runners, the flow exists at a

radius different than from the radius at the inlet. If the flow enters the runner

with only radial and tangential components, it is a radial flow machine. The

flow enters a mixed flow runner with both radial and axial components.

Francis turbines are of radial and mixed flow types, depending on the design

specific speed. A Francis turbine is illustrated in fig. The efficiency of francis

turbine varies from 80% to 85%.

FIG.5.2 Impulse turbine vs Reaction turbine

FIG 5.3 FRANCIS TURBINE

5.2.3TURBINE SPECIFICATIONS-

FRANCIS HYDRAULIC TURBINE

KW 52.00Net head 49.7MRPM 125No. of blades 16Designed by KMW and Johnson & co. ltdBuilt by Marine industries ltd. Sorei, queInstalled 1969

Table 5.1

5.2.4 Design and manufacture of turbines

Kaplan Francis Pelton

Head :1.80/25m Runner

blades :4/5/6 Runner diameter:

700mm to 4000mm

Arrangements Vertical simple or

Double regulated Horizontal simple

orDouble regulated

Inclined simple regulated

Siphon intake Power: 100kw to

7mw

Head:15m/200m Runner

diameter:250mm/ 3500mm

Specific speed from 90 to 425

Arrangements Vertical shaft Horizontal shaft Semi spiral

casing or full spiral casing

Double francis (2 runners)

Power:500kw to 15kw

Head:100m/1000m Diameter of the

wheel till 1800mm

Arrangements Vertical 3 jets/4 jets Horizontal

1jet/2jets Double (horizontal

4 jets) Power:100kw to

10mw

Table 5.2

5.2.5 Level of Equipment

Floor Level (feet) Equipments Dam road 1172 60 ton EOT crane

Entrance to penstock gate gallery Switch yard 1084 102kv switch yard including 9

circuit breakers, 3 SF6 breaker & associated equipments

33/11kv-1MVA transformer Entrance to bypass valve High head discharge pump house for

emulsifier tank Top of EOT crane 1052 125 ton EOT craneWorkshop 1040 Machine shop

Oil handing tanks 3.3/0.4 kv transformer of diesel 250KVA,400V diesel generator

Control room 1025 Control room Transformer yard High head discharge pumps for

rainy season Dewatering pumps Station auxiliary transformer Air conditioning system

Service boy and divisional storeMachine hall 1006 11kv switch gear system

440V breaker and lighting system PLCC room Cable room Exciter and PMG of generator

Turbine pit 985.5 Sump pump for dewater the sump tankDt manhole 969Dt gallery 957.5Bottom of craft tube

939

Bottom of sump 939.5 Table 5.3

5.2.6 Mounted on unit control board

Temperature indicator with 14 position transfer switch 4-point generator, stator 4-point cooler air outlet 2-point test 4-points spare 4- temperature indicators, foxbaro rotax vapour pressure, dial type with

alarm contacts 1-generator thrust bearing 1-generator guide bearing 1-oil reservoir 1-turbine bearing Rotor temperature indicator with 2 alarm contacts

CHAPTER 6

POWER TRANSFORMER

Power transformer is used for stepping up the voltage for transmission.

Generally Δ-Y connected power transformers are used. They are oil-immersed

transformer. The transformer connection is generally shown by vector group.

The vector groups of power transformers of RPS power plant are Yd11.

6.1 TRANFORMER RATING

KVA 55000

Phase 3

Cycle 50Hz

Input 11KV(delta)

Output 132KV(star)

Cooling OFW-55°C

Table 6.1

Cooling water

Cooler -55000 KVA 109 GPM

Cooler-60000 KVA 150 GPM

6.2 GOVERNING SYSTEM

In order to have electrical output if constant frequency it is necessary to

maintain speed of the alternation driver with the turbine constant. An operation

of speed regulation is called the governing. It is attained automatically by

means of a governor. The principle elements of the governor are-

The speed responsive elements usually fly ball mechanism or speed

governor

Control value or rally value to the either side of servomotor piston

Servomotor along with fluid pressure operates piston to activate the

turbine control mechanism

The restoring mechanism or follow up linkage to hold servomotor in the

required fixed position. When the input and output are equalized

The fluid pressure supply require for the action of servomotor.

6.3 ELECTRICAL EQUIPMENT

Generator

The generators used in hydro power plant are usually three phase

synchronous machines. The generators have the speed range of 70-1000

RPM. Generators have either a vertical shaft arrangement or horizontal

shaft arrangement. But the vertical shaft arrangement is preferred. The

generator cooling can be achieved by air circulation through the stator

ducts

6.3.1 Main components of generator

Stator

The 396 slot stator is wound with diamond type coils containing four

windings and connects 6 circuit wires with 6 main and 3 neutral leads

brought out. Resistance between lines at 25 centigrade is 0.01348 ohms.

Stator winding insulation is class b, the ground installation segment of

which is asphalt-mica.

Rotor

The field coils are lubricated strip wound, 27 turns per pole in class B

installation. Resistance of the 48 posts field windings 0.196 ohms at 25

centigrade.

Main bracket

All rotating parts in addition to hydraulic thrust are supported through

the thrust bearing by the main bracket has 4 arms resting on the edge of

the turbine pit. At the end of each bracket arms are mounted two units of

counted brackets and jacks.

Housing and cooler

Totally enclosed in an octagonal steel housing 38’-1’ across flats, with

top flush with upper bracket arms. Approx. 120000CFM of ventilating

air passes through the rim and between passes through the stator and

finally through the air coolers before recycling. Air coolers are 8 inch

mounted symmetrical around the machine.

Maximum tested pressure is 10kg/cm square.

CHAPTER 7

ELECTRICITY GENERATION

FIG7.1HYDROELECTRIC POWER

7.1 HYDROELECTRIC POWER: HOW IT WORKS

So just how do we get electricity from water? Actually, hydroelectric and coal

fired power plants produce electricity in a similar way. In both cases a power

source is used to turn a propeller-like piece called a turbine, which then turns a

metal shaft in an electric generator, which is the motor that produces

electricity. A coal-fired power plant uses steam to turn the turbine blades,

where as a hydroelectric plant uses falling water to turn the turbine. The result

is the same.

FIG7.2 GENERATOR

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. 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 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 mines. The water continues

past the propeller through the tailrace 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 hydro electric generator converts this mechanical energy into

electricity.

The operation of a generator is based on the principle 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

laminations. These are called field poles and it is mounted on the perimeter of

the rotor. The ro is attached to the turbine shafts 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 the electricity to

flow and a voltage to develop at the generator output terminals”.

Most hydroelectric power comes from the potential energy of dammed water

driving a water turbine and generator. In this case the energy extracted from

the water depends on the volume and on the difference in height between the

source and the water’s outflow. This height difference is called the head. The

amount of potential energy in water is proportional to the head. To obtain very

high head, water for a hydraulic turbine may be run through a large pipe called

a penstock.

Pumped storage hydroelectricity produces electricity to supply high peak

demands by moving water between reservoirs at different elevations. At the

times of low electrical demand, excess generation capacity is used to pump

water in to the higher reservoir. When there is higher demand, water is

released back into the lower reservoir through the turbine. Pumped storage

schemes currently provide the only commercially important means of large

scale grid energy storage and improve the daily load factor of the generation

system. Hydroelectric plants with no reservoir capacity are called run of the

river plant, since it is not possible to store the water. A tidal power plant makes

use of the daily rise and fall of water due to tides, such sources are highly

predictable and if conditions permit construction of reservoirs can also be

dispatch able to generate power during high demand periods.

Less common types of hydro schemes use water’s kinetic energy or

undammed sources such as undershot waterwheels.

A simple formula for approximately electric power production at a

hydroelectric plant is-

P =hrgk,

Where,

P is power in kilowatts

h is height in meters

r is flow rate in cubic meters per second

g is acceleration due to gravity

k is a coefficient of efficiency ranging from 0 to 1

Efficiency is often higher with larger and more modern turbines.

Annual electric energy production depends on the available water supply. In

some installations the water flow rate can vary by a factor of 10:1 over the

course of a year.

7.2 INDUSTRIAL HYDROELECTRIC PLANTS

While many hydroelectric projects supply public electricity networks, some

are created to serve specific industrial enterprises. Dedicated hydroelectric

projects are often built to provide the substantial amounts of electricity needed

for aluminum electrolytic plants.

7.3 SMALL SCALE HYDRO ELECTRIC PLANTS

Although large hydroelectric installations generate most of the worlds

hydroelectricity , some situations require small hydro plants. These are defined

as plants producing up to 10 megawatts or projects up to 30 megawatts in

north America. A small hydro power plant may be connected to a distribution

grid or may provide power to a isolated community or a single home. Small

hydro projects generally do not require the protracted economic, engineering

and environmental studies associated with large projects and often may be

completed much more quickly. A small hydro development may be installed

along with a project with flood control, irrigation or other purposes providing

extra revenue for project costs. In areas that formerly used waterwheels for

milling and other purposes often the site can be redeveloped for electric power

production, possibly eliminating the new environmental impact of any

demolition operation. Small hydro can be further divided into mini hydro units

around 1MW in size and micro hydro with units as large as 100KW down to

couple of KW rating.

Small hydro schemes are particularly popular in china, which has over 50% of

world small hydro capacity. Small hydro units in the range of 1MW to about

30MW are often available from multiple manufacturers using standardized

“water to wire” packages, a single contractor can provide all the major

mechanical and electrical equipment (turbine, generator, controls, switchgear),

selecting from several standard designs to fit the site conditions. Micro hydro

projects use a diverse range of equipments, in the smaller sizes industrial

centrifugal pumps can be used as turbines with comparatively low purchases

cost compared to purpose built turbines.

7.4 ADVANTAGES

The upper reservoir and dam of the festiniog pumped storage scheme. 360

MW of electricity can be generated within 60 seconds of the need arising.

7.5 ECONOMICS

The major advantage of hydro electric is elimination of the cost of fuel. The

cost of operating a hydroelectric plant is nearly immune to increase in the cost

of fossil fuels such as oil, natural gas or coal and no imports are needed.

Hydroelectric plants also tend to have longer economic lives than fuel fired

generation, with some plants now in service which were built 50 to 100 years

ago.

Operating labor cost is also usually low, as plants are automated and have few

personnel on site during normal operation.

When a dam serves multiple purposes, a hydro electric plant may be added

with relatively low construction cost, providing a useful revenue stream to

offset the costs of dam operation.

7.6 GREEN HOUSE GAS EMMISSIONS

Since hydro electric dams do not burn fossil fuels, they do not directly produce

carbon dioxide. While some carbon dioxide is produced during manufacture

and construction of the project, this is a tiny fraction of the operating emissions

of equivalent fossil fuel electricity generation.

7.7 RELATED ACTIVITIES

Reservoirs created by hydroelectric schemes often provide facilities for water

sports, and become tourist attractions in themselves. In some countries,

aquaculture in reservoir is common. Multi uses dams installed for irrigation

support agriculture with a relatively constant water supply. Large hydro dams

can control floods, which would otherwise affect people living downstream of

the project.

7.8 DISADVANTAGES

The power produced by the plant depends upon the quantity of water

which in turn is dependant upon the rainfall, so if the rainfall is in time

and proper and the required amount of water is collected, the plant will

function satisfactory otherwise not.

Hydro electric plants are generally situated away from the load centers.

They require along transmissions lines to deliver power. Therefore the

cost of transmission lines and losses in them will be more.

Initial cost of plant is high.

It takes fairly long time for the erection of such plants.

7.9 HYDRO ELECTRIC POWER STATIONS AND

ENVIRONMENT

Hydro electric power plants are most efficient electricity generators. They

produce no green house gases and are ideal way to store electricity. However,

building hydro electric plants can have serious consequences for both the

environment and the people. Damming a watercourse normally results in the

flooding of the surrounding area with the consequent loss of flora and fauna.

People living in the area can be displaced for the same reason.

Even though a hydroelectric plant produces no green house gases they can

have a impact on the greenhouse effect. The carbon on the flooded land has to

be considered. It has been proposed that as a size of the lake associated with

the flooding due to a hydroelectric scheme increases, so does the amount of

carbon dioxide equivalent emissions. The amount of the carbon that is

converted to methane increases with the size of the lake. However, this

decreases as the output of the hydro schemes and its lifetime increases. Over a

period of a hundred years, methane has a warning effect twenty one times that

of carbon dioxide. More research into this aspect of hydro electric plants is

required.

7.10 COMPARISON WITH OTHER METHODS OF POWER

GENERATION

Hydro electricity eliminates the flue gases emissions from fossil fuel

combustion, including pollutants such as sulfur dioxide, nitric oxide, carbon

monoxide, dust and mercury in the coal. Hydroelectricity also avoids the

hazards of the coal mining and the indirect health effects of coal emissions.

Compared to nuclear power, hydroelectricity generates no nuclear wastes, has

none of the dangers associated with uranium mining, nor nuclear leaks. Unlike

uranium, hydroelectricity is also a renewable energy source.

Compared to the wind farms, hydroelectricity power plants have a more

predictable load factor. If the project has a storage reservoir , it can be

dispatched to generate power when needed. Hydroelectric plants can be easily

regulated to follow variation in power demand.

Unlike fossil fueled combustion turbines, construction of a hydroelectric plant

requires a long lead time for site studies, hydrological studies, and

environmental impact assessment. Hydrological data up to 50 years or more is

usually required to determine the best sites and operating regimes foe a large

hydroelectric plant. Unlike plants operated by fuels, such as fossil and nuclear

energy, the number of sites that can be economical developed for hydro

electric production is limited in many areas the most cost effective sites have

already been exploited. New hydro site tends to be far from population centers

and require extensive transmission lines. Hydro electric generation depends

upon rainfall in watershed and may be significantly reduced in years of low

rainfall or snowmelt. Long term energy yield may be affected by climate

change. Utilities that primarily use hydro electric power may spend additional

capital to build extra capacity to ensure sufficient power is available in low

water years.

Hydro power is one of the three principle source of energy used to generate

electricity, the other two being fossil fuels and nuclear fuels. Hydro electricity

has certain advantages over these other sources: it is continuously renewable

thanks to the recruiting nature of the water cycle, and causes no pollution. Also

ii is one of the cheapest sources of electrical energy.

The electrical power obtained from conversion of potential and kinetic energy

of water is called hydropower.

PE=WZ

Where

PE is potential energy

W is total weight of water

Z is vertical distance travelled by water

Power is the rate at which energy is produced or utilized

1 horsepower(hp) = 550 ftlb/s

1 KW = 738 ft lb/s

CHAPTER 8

ELECTRICAL SYSTEM

The generation of the electricity is at 11KV and transmitted on 132 KV. There

are four transmission lines from the RPS power plant, two lines to Kota and

other two to Bhilwara, two lines to Gandhi sagar and one industrial line.

8.1 MAJOR ELECTRICAL EQUIPMENT WITH THERE

SPECIFICATIONS

8.1.1 ALTERNATOR:

At the RPS hydel power plant vertical overhung type alternator is used, with

one thrust and one guide bearing both located below the rotor. The alternator

used with Francis turbine of vertical configuration. The vertical generators at

RPS are very low about 125 RPM so no. of poles are 48.

8.1.2 ALTERNATOR RATING

Model 100780

Type ATI

Class 48-47778-125

Cycles 50

Volts 11000

RPM 125

KVA 47778

KW 43000

AMP 2515

Excitation volts 250

Amp. Excitation 854

Max. stator temp. raise 55°C

Table 8.1

Stator temperature raise measured by RTD rotor temperature raise measured

by resistance.

8.2 CURRENT TRANSFORMER

These instrument transformers are connected in ac power circuits for leading

the current coils of indicating and meeting (ammeters, watt meters, watt hour

meters) and protective relays.

Thus the CT broadens the limit of measurements and maintain a watch over

the current flowing in the circuits and over the power load. In high voltage

installations CT in addition to above also isolates the indicating and metering

instruments fron high voltages. The CT basically consists of an iron core on

which few turns of primary is directly installed of the power circuit and to the

secondary winding the indicating or metering instruments or relay is

connected. When the rated current of CT flows through its primary winding a

current of 5 amperes will appears in its secondary winding. The primary

winding is usually single turn and the no. of turns on secondary depends upon

the power circuit current to be measured.

The larger current to be secondary current is known as transformation ration of

CT. The CT are rated for voltage of the installations the rated current of the

primary and secondary winding and the accuracy class. The accuracy class

indicates the limit of the errors in percentage of the rated turn ratio of the given

current transformer is available in the accuracy classes 0.5, 1.3 and 10.

Basically CT is a step up transformer. It is a primary side current is high and

secondary side current is less than 5A, which is used for protection of meeting

purpose. Its primary is always connected in series.

8.2.1 CURRENT TRANSFORMER RATING

VICTRANS ENGINEERS,NAGPUR(INDIA)

High system voltage 145KV

Frequency 50Hz

Insulation level 275/650KV

Type C-1140

Short time thermal current 31.5KV

Ratio 200-400/5-5.5A

TABLE 8.2

GENERAL ELECTRIC,CANADA

Type CTP-15

Ratio 3000-5amps

Cycles 25-60

Max. continuous amp 4500 at 35°C

INS CLASS 0.6Kr

CAT no. 4.0732XX3

TABLE8.3

8.3 POTENTIAL TRANSFORMER

The potential transformers are employed for voltages above 380 volts to feed

the potential coils of indicating and metering instruments (voltmeters, watt

meter, watt hour meter) and relays. These transformers make the ordinary low

voltages instruments suitable for measurement of high voltages and isolate

them from high voltages. The primary winding of the potential transformer is

connected to the main bus-bars of the switch gear installation and the

secondary winding various indicating and metering instruments and relays are

connected when the rated high voltage is applied the primary of PT. The

voltage of 110 volts appears across the secondary winding. The ratio of the

rated primary voltage to rated secondary voltage is known as transformers

ratio.

The potential transformers are rated for primary and secondary rated voltage,

accuracy, class, no. of phases and system of cooling. Basically P.T.’S are step

down transformer. They are only used foe metering purpose. Its secondary

voltage is about of 110 volts and these are connected in parallel with the line.

8.4 CIRCUIT BREAKER

Circuit breakers are mechanical devices designed to close or open contact

members, thus closing or opening an electrical circuit under normal or

abnormal conditions. Circuit breakers are rated in terms of maximum voltage,

no. of poles, frequency, maximum continuous current carrying capacity and

maximum momentary and 4 second current carrying capacity.

The interruption or reparsing capacity of a circuit breaker is the maximum

value of current which can be interrupted by it without any damage.

The circuit breakers are classified on the basis of the medium used for arc

extension.

8.4.1 THE TYPES OF CIRCUIT BREAKERS –

SF6 circuit breaker

Bulk oiled circuit breakers

Air blast circuit breakers

Vacuum circuit breakers

Minimum oil circuit breakers

Air circuit breakers

Miniature circuit breakers

The circuit breakers are automatic switches, which can interrupt fault currents.

The part of the circuit breakers connected in on phase is called the pole. A

circuit

Breakers suitable for three phase is called the pole. A circuit breaker suitable

for three phase system is called a triple pole circuit breaker. Each pole of the

circuit breaker comprises one or more interrupters or arc extinguishing

chambers. The interrupters are mounted on the support insulators. The

interrupter encloses a set of fixed and moving contact. The moving contacts

can be drawn spark by means of the circuit breakers given the necessary

energy for opening and closing of contacts of the circuit breakers.

The arc produced by the separation of current carrying contact is interrupted

by a suitable medium and by adopting suitable techniques for arc extinction

medium.

CHAPTER 9

SF6 GAS CIRCUIT BREAKERS

Sulfur hexafluoride (SF6) is an excellent gaseous dielectric for high voltage

power applications. It has been used extensively in high voltage circuit

breakers and other switchgears employed by the power industry. Applications

for SF6 include gas insulated transmission lines and gas insulated power

distributions. The combined electrical, physical, chemical and thermal

properties offer many advantages when used in power switchgears. Some of

the outstanding properties of SF6 making it desirable to use in power

applications are:

Very high dielectric strength

Very unique arc quenching ability

Excellent thermal stability

Good thermal conductivity

9.1 GENERAL INFORMATION

SF6 circuit breakers are equipped with separated poles each having its own

gas. In all types of the circuit breakers, gas pressure is 2 bars( absolute 3 bars).

Even if the pressure drops to 1 bar, there will be no change in the breaking

properties of the circuit breakers due to the superior features of SF6. During

arcing, the circuit breakers maintains a relatively low pressure ( max 5-6 bars)

inside the chamber and there will be no danger of explosion and s[pilling of

the gas around. Any leakage from the chamber will not create a problem since

SF6 can undergo considerable decomposition, in which some of the toxic

products may stay inside the chamber in the form of the white dust.

Fig 9.1 SF6 circuit breaker

If the poles are dismantled for maintenance, it needs special attention during

removal of the parts of the pole. This type of maintenance should be carried

out only by the experts of the manufacturer.

9.2 OPERATION OF CIRCUIT BREAKER

In general, the circuit breakers consist of two main parts, the poles and the

mechanism. The poles consist of contact and arc-extinguishing devices. the

mechanism is the part to open or close the contacts in the poles at the same

time simultaneously . the closing and opening springs are the first charged. If

“close” button is pressed the opening springs get charged while the contacts

get closed. Thus, circuit breaker will be ready for opening. The mechanical

operating cycle of the circuit breaker is used with re-closing relay. In that

case, after the closing operation , the closing springs are charged by the

driving lever or by driving motor . thus, the circuit breaker will be ready for

opening and re-closing.

Elimsan breaker mechanism can perform 10,000 opening-closing operations

without changing any component. The mechanical life of the circuit breaker is

minimum 10,000 operations. However, it needs a periodical maintenance

depending on its environment. In ideal working condition s, lubrication once a

year or after every 1000 operations is sufficient. In dusty and damp

environment, the mechanism should be lubricated once every 3-6 months or

after every 250-500 operations.

The machine oil and grease with molybdenum must be used for lubricating.

Owning to mechanisms capability of operating between -5C and +40C , it

does not require a heater.

9.3 AUXILARY SWITCH

The auxiliary switch mounted on the circuit breakers has 12 contacts. One of

them is for anti-pumping circuit, four of them are allocated for opening and

closing coils. The remaining 7 contacts are spare. Three of them are normally

opened and four are normally closed. When it is necessary, the no. of the

contacts can be increased.

9.4 RAPID AUTOMATIC RECLOSING

The circuit breaker which opens due to a short circuit failure, can be re closed

automatically after a pre selected time by arc closing relay, assuming the fault

is temporary. Thus, we avoid long time power loss in case of temporary short

circuits. But, if the fault lasts after re-closure, the protection relay will trip to

open the circuit breakers again.

When manual or motor drive is used, the circuit breaker will be ready to close.

The closure can be actuated pressing the closing button located on the circuit

breaker. It is recommended to close it using remote control system for secure

operations. The opening can be performed either by opening button or remote

controlled opening coil. In case of a fault, the relay signal actuates the opening

coil and circuit breaker opens. In addition, there is an anti-pumping relay for

preventing the re-closing and opening of the circuit breaker more than one

cycle(O-C-O) and for preventing possible troubles created by remote closing

button.

9.5 COMMISSIONING

The outer surface of epoxy insulating tubes o the poles are to be wiped out

with a clean and dry cloth. The wiring and connections of the auxiliary circuit

are to be carefully examined. DC voltage should be checked to see whether it

is suitable for coil and motor or not.

Table 9.2 CROSS SECTION OF SF6 CIRCUIT BREAKER

The opening closing coils are to be operated 15-20 times and the accuracy of

relay circuit is to be checked before energizing the circuit breaker. The circuit

breaker is to be mounted with two MI2 bolts through its anchoring shoes. It

should not move during operation. No excessive load should be exerted to the

poles and if possible flexible cables are used. The incoming and outgoing

contacts must have clean surfaces and their contact resistance should be as

low as possible. When connecting the circuit breaker to protection system and

auxiliary supply, the cable cross sections should be according to the table

given. The circuit breaker must be grounded through at least 16mm steel tape.

After all, the following procedure must be performed-

Open the isolator of the circuit breaker

Prepare the circuit breaker for closing operation by driving mechanism

Close the isolator of circuit breaker firmly

Send the closing signal to the circuit breaker

CHAPTER 10

FIRE PROTECTION SYSTEM

10.1 FIRE PROTECTION SYSTEM

10.1.1 SMOKE DETECTOR SYSTEM

Smoke detectors are provided at different areas of the plant, which will operate

and generate an alarm in C/R in case of any fire in that area to take corrective

and timely action.

10.1.2 MULTIFIRE SYSTEM

All big transformers are protected by high velocity “Multi-fire projectors”

erected about and above the equipments are required. The projectors are

coupled together on a pipe work system to an automatic deluge valve assembly

consisting of strainer, isolating valve and a quick opening deluge valve for

control of the water supply.

The automatic deluge valve is operated by means of a separate detector pipe

work system on which quartzoid bulbs are mounted filled with liquid of high

expansion coefficient.

The detector system is charged with compressed air. In the event of a fire, one

or more of these bulbs will burst due to expansion of liquid and allowing

compressed air to escape from the pipe work. When the air pressure has fallen

the deluge valve opens and brings the multi-fire projectors to action and starts

water supply spray on the equipments automatically and protect them from

fire.

Alarming sound will generate the operation of the system to alert to staff to

take further course of action.

10.2 ISOLATOR

Isolator are not equipped with a quenching device and therefore are not used to

open circuits carrying current, as the name implies solatores one portion of the

circuit from another and is not intended to be opened while current is flowing.

Isolators must not be opened until the circuit is interrupted by some other

means. If an isolator is opened carelessly when carrying a heavy current, the

resulting arc could easily cause a flash over the earth. Thus may shatter the

supporting isolators and may even cause a fatal accident to the operator,

particularly in high voltage circuits.

10.3 EARTHING SWITCH

Earthing switch is connected between the line conductor and the earth.

Normally it is open when the line is disconnected, the earthing switch is closed

so as to discharge the voltage trapped on the line capacitance to the earth.

Through the line is disconnected, there is some voltage on the line to switch

the capacitance between line and earth is charged. The voltage is significant in

high voltage system. Before proceeding with the maintenance work the voltage

is discharged to earth by closing the earthing switch. Normally the earthing

switch is mounted on the frame of isolators.

BIBILOGRAPHY

1. http://www.rvunl.com/RPS.php

2. http://www.mannvit.com/HydroelectricPower/HydroelectricPowerPlants/

3. http://services.indiabizclub.com/catalog/635880~gas+refilling+in+sf6+breaker~faridabad

4. http://mygreenchannel.org/