Project Report on water turbines

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FABRICATION OF HYDEL POWER PLANT 2012

CHAPTER 1

SYNOPSIS

Water turbines convert Mechanical rotary energy into Electrical energy. A mechanical

interface, consisting of a step-up gear, water Pump and a suitable coupling transmits the

energy to an electrical generator. The output of this generator is connected to the Battery

or system grid. The battery is connected to the inverter. The inverter is used to convert

DC voltages to AC voltages. The load is drawn current from the inverter.

1. Generator

2. Mains haft with Leafs

3. Gear Wheel Arrangement

Water power ratings can be divided into three convenient grouping, small to 1kW,

medium to 50 kW and large 200 kW to megawatt frame size.

Dept. of MechanicalEngg. ,MVJCE

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CHAPTER 2

INTRODUCTION

Energy is the most important thing in this world. All living plants, animals

(organisms) on this earth require energy to perform any type of work. The capacity to do

a work is energy. The energy may require in smaller amount or in larger amount

depending upon the nature of work to be performed.

The different things from which we get the energy are called as Energy Sources. This isthe simplest meaning of energy sources. There are two types of energy sources:

1 Conventional OR Non-Renewable Energy Sources

2 Non-Conventional OR Renewable Energy Sources

1 Conventional OR Non-Renewable Energy Sources:

The energy sources, which we are using from long time and which are in danger of

exhausting, are called as Conventional OR Non-Renewable Energy Sources. They are notrenewed by Nature and they are perishable, are going to get exhausted one day.

e. g. coal, petroleum products, nuclear fuels etc.

2. Non-Conventional OR Renewable Energy Sources:

These are the energy sources whose utilization technology is not yet fully developed.

These are the sources, which can be recovered and reused. i. e. they can be used again and

again to generate energy because of the renewal of their energy

We are going to consider one of the ways of generation of energy from non-conventionalenergy namely hydroelectric energy. As name suggest, it is the energy obtained from

water.

The main principle used in this type is the kinetic energy of falling water is converted into

electric energy using turbines.

Hydro-electric power is electricity produced by the flow of fresh water from lakes,

rivers, and streams. As water flows downwards thanks to gravity the kinetic energy it

carries increases. This kinetic energy can be converted into mechanical energy - e.g. by

turning a turbine - and from there into electrical energy. In the right location hydro-


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electric generation is far more cost effective than PV solar cells orwind turbines in

terms of Watts generated per spent.

Fig 2.1

How much electrical energy can be generated by a hydroelectric turbine depends on the

flow/quantity of water, and the height from which it has fallen (the head). The higher the

head, and the larger the flow, the more electricity can be generated.

Click here to view our article Calculation of Hydro Power to find out more.

The image above shows the Rainbow Power 300 Watt Hydro Generator which costs

around 1,300.

Hydropower Around the World


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Fig 2.2

By 2004, 6% of the world's electricity was hydro, some of that generated in enormous

GigaWatt rated hydro power stations in Asia and Australia amongst other places

including the World's largest hydropower plant at the Three Gorges Dam in China.

Howevermicro-hydro (a small localised hydro electic turbine) is also very useful for

farmers and other people in remote locations. A part of a nearby river is diverted through

a turbine to generate electricity and then the water is returned to the river at a lower point

reducing the environmental impact. This is known as a run of river hydro power

system.

Where the flow of water is regular it is possible to set up a 240 AC hydro system which

can be turned on whenever power is needed. Alternatively lower voltage DC electricity

can be generated and stored in batteries for later use (via a 240V power inverter).

2.1 HISTORY OF HYDEL POWER DEVELOPMENT

The first recorded use of water power was a clock, built around 250 BC. Sincethat time, humans have used falling water to provide power for grain and saw mills, as

well as a host of other applications. The first use of moving water to produce electricity


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was a waterwheel on the Fox River in Wisconsin in 1882, two years after Thomas Edison

unveiled the incandescent light bulb. The first of many hydro electric power plants at

Niagara Falls was completed shortly thereafter. Hydro power continued to play a major

role in the expansion of electrical service early in this century, both in North America and

around the world. Contemporary Hydro-electric power plants generate anywhere from a

few kW, enough for a single residence, to thousands of MW, power enough to supply a

large city.

Early hydro-electric power plants were much more reliable and efficient than the

fossil fuel fired plants of the day. This resulted in a proliferation of small to medium sized

hydro-electric generating stations distributed wherever there was an adequate supply of

moving water and a need for electricity. As electricity demand soared in the middle years

of this century, and the efficiency of coal and oil fueled power plants increased, small

hydro plants fell out of favor. Most new hydro-electric development was focused on huge

"mega-projects".

The majority of these power plants involved large dams which flooded vast

areas of land to provide water storage and therefore a constant supply of electricity. In

Recent years, the environmental impacts of such large hydro projects are being identifiedas a cause for concern. It is becoming increasingly difficult for developers to build new

dams because of opposition from environmentalists and people living on the land to be

flooded. This is shown by the opposition to projects such as Great Whale (James Bay II)

in Quebec and the Gabickovo-Nagymaros project on the Danube River in

Czechoslovakia.

Hydropower generation is an improvarient of primitive water wheel for

grinding cereals. As hydro-electric power it emerged in USA in1882, followed by

sweeden and Japan. In India, hydropower plant OF 130kw installed capacity was

commissioned in 1897 at sidrapong at Dargiling in West Bengal and followed by 4.5MW

plant at sivsamudram in Karnataka in 1902.during period between two world wars, a

number of hydro power plants such as 48MW, at Jogindernagar(H.P.),17.4MW ganga

power plant(U.P.), 38.75MWpykaraand 30MWmatter(Chnnai)were commissioned, from

installed capacity of 1362MW,out of which hydropower was 508 MW in 1947,the pace of

growth has been rapid in post independence era. The hydal install capacity by the end

2001 is 25,574MW, out of total capacity of 102907MW.


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2.2 HYDROELECTRIC POWER

Electricity produced from generators driven by water turbines that

convert the energy in falling or fast-flowing water to mechanical energy. Water at a

higher elevation flows downward through large pipes or tunnels (penstocks). The

falling water rotates turbines, which drive the generators, which convert the turbines'

mechanical energy into electricity. The advantages of hydroelectric power over such

other sources as fossil fuels and nuclear fission are that it is continually renewable

and produces no pollution. Norway, Sweden, Canada, and Switzerland rely heavily

on hydroelectricity because they have industrialized areas close to mountainous

regions with heavy rainfall. The U.S., Russia, China, India, and Brazil get a much

smaller proportion of their electric power from hydroelectric generation. See also

tidal power.Water is needed to run a hydroelectric generating unit. Its held in a

reservoir or lake behind the dam and the force of the water being released from the

reservoir through the dam spins the blades of a turbine. The turbine is connected to

the generator that produces electricity. After passing through the turbine, the water

reenters the river on the downstream side of the dam.

The capability to produce and deliver electricity for widespread

consumption was one of the most important factors in the surge of American

economic influence and wealth in the late nineteenth and early twentieth centuries.

Hydroelectric power, among the first and simplest of the technologies that generated

electricity, was initially developed using low dams of rock, timber, or granite block

construction to collect water from rainfall and surface runoff into a reservoir. The

water was funneled into a pipe (or pen-stock) and directed to a waterwheel (or

turbine) where the force of the falling water on the turbine blades rotated the turbineand its main shaft. This shaft was connected to a generator, and the rotating

generator produced electricity. One gallon (about 3.8 liters) of water falling 100 feet

(about 30 meters) each second produced slightly more than 1,000 watts (or one

kilowatt) of electricity, enough to power ten 100-watt light bulbs or a typical

hairdryer.

There are now three types of hydroelectric installations: storage, run-

of-river, and pumped-storage facilities. Storage facilities use a dam to capture waterin a reservoir. This stored water is released from the reservoir through turbines at the

rate required to meet changing electricity needs or other needs such as flood control,


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fish passage, irrigation, navigation, and recreation. Run-of-river facilities use only

the natural flow of the river to operate the turbine. If the conditions are right, this

type of project can be constructed without a dam or with a low diversion structure to

direct water from the stream channel into a penstock. Pumped-storage facilities, an

innovation of the 1950s, have specially designed turbines. These turbines have the

ability to generate electricity the conventional way when water is delivered through

penstocks to the turbines from a reservoir. They can also be reversed and used as

pumps to lift water from the powerhouse back up into the reservoir where the water

is stored for later use. During the daytime when electricity demand suddenly

increases, the gates of the pumped-storage facility are opened and stored water is

released from the reservoir to generate and quickly deliver electricity to meet the

demand. At night when electricity demand is lowest and there is excess electricity

available from coal or nuclear electricity generating facilities the turbines are

reversed and pump water back into the reservoir. Operating in this manner, a

pumped-storage facility improves the operating efficiency of all power plants within

an electric system. Hydroelectric developments provide unique benefits not available

with other electricity generating technologies. They do not contribute to airpollution, acid rain, or ozone depletion, and do not produce toxic wastes. As a part

of normal operations many hydroelectric facilities also provide flood control, water

supply for drinking and irrigation, and recreational opportunities such as fishing,

swimming, water-skiing, picnicking, camping, rafting, boating, and sightseeing.

2.3 HYDRO ELECTRIC POWER PLANTInstallations (e.g. Dams) to a large extent. Manufacturers have been quick

enough to develop package designs for small units. These are also called as Small Scale

Hydroelectric Power Plants. These facilities can supply in principle significant amounts

of electricity for irrigation, or potable water pumping lighting or health or educational

purpose. The total potential amount of such resources is poorly documented but is apt to

be large.

Up to 1972, hydro engineers concentrated on developing the larger sites,where the economy of scale enabled the production of energy at a cost low enough to

compete thermal power etc. But the shortage of fuel, high cost of fuels needed for many


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of the other plants made the engineers to pay attention to the naturally occurring

renewable sources which can be efficiently used as energy sources. Moreover, the

remarkable advancement in the technology of development of turbines suitable for

utilizing small falls and small discharges from RIVERS increased the chances of

development of small hydral For many small hydro plants of less than 500 kW capacity,

electronic load controllers have been developed to replace the governor. These

controllers maintain a constant load on the turbine and hence constant flow, surplus

power is diverted to a resistor and either wasted or used to heat water.

The advantage of Hydro Power Plants operation in hilly areas and remote areas and the

elimination of long transmission system, & lesser gestation periods have lent added

attraction. It has little or no adverse environmental impact, effects on stream ecology.

In India, the potential of small hydropower is estimated to be 5000

MW at present, while further investigations and surveys are expected to indicate

a higher potential. Small Hydropower is covered in renewable programme. The alternate

hydro-energy center at Roorki works on the development of solar hydropower system as

well as Hybrid Hydro systems. If small hydropower stations are set up all over the

country, decentralized availability of power will become possible.Many countries now have active small hydro development and rural electrification

programmes, due to the several advantages offered by these plants.

There is no formal definition of a small hydro plant but this may generally be taken as

power station or plant having output up to 5000 kW. Some associate the concept of small

hydro with low head say up to 15 m. This may not generally be true as there is no

restriction on head for these power plants. Stations up to output 1000 kW are called

micro and up to 5000 kW as mini power plants. Conceptually these power plants can be

categorized into two types:

1) One utilizing small discharges but having high head

2) One utilizing large discharges but having comparatively smaller head. Hydro-electric

power plants convert the kinetic energy contained in falling water into electricity. The

energy in flowing water is ultimately derived from the sun, and is therefore constantly

being renewed. Energy contained in sunlight evaporates water from the oceans and

deposits it on land in the form of rain. Differences in land elevation result in rainfall

runoff, and allow some of the original solar energy to be captured as hydro-electric

power.


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Hydro power is currently the world's largest renewable source of

electricity, accounting for 6% of worldwide energy supply or about 15% of the world's

electricity. In Canada, hydroelectric power is abundant and supplies 60% of our

electrical needs. Traditionally thought of as a cheap and clean source of electricity, most

large hydro-electric schemes being planned today are coming up against a great deal of

opposition from environmental groups and native people.

2.4 HYDRO-ELECTRIC POWER PLANTS

Hydroelectric energy is produced by the force of falling water. The capacity

to produce this energy is dependent on both the available flow and the height from which

it falls. Building up behind a high dam, water accumulates potential energy. This is

transformed into mechanical energy when the water rushes down the sluice and strikes

the rotary blades of turbine. The turbine's rotation spins electromagnets which generate

current in stationary coils of wire. Finally, the current is put through a transformer where

the voltage is increased for long distance transmission over power lines.

Hydro-electric power plants capture the energy released by water falling through a

vertical distance, and transform this energy into useful electricity. In general, falling

water is channeled through a turbine which converts the water's energy into mechanical

power. The rotation of the water turbines is transferred to a generator which produces

electricity. The amount of electricity which can be generated at a hydro-electric plant is

dependant upon two factors. These factors are (1) the vertical distance through which the

water falls, called the "head", and (2) the flow rate, measured as volume per unit time.

The electricity produced is proportional to the product of the head and the rate of flow.

The following is an equation which may be used to roughly determine the amount ofelectricity which can be generated by a potential hydro-electric power site:

POWER (kW) = 5.9 x FLOW x HEAD

In this equation, FLOW is measured in cubic meters per second and HEAD is measured

in meters.

Based on the facts presented above, hydroelectric power plants can

generally be divided into two categories. "High head" power plants are the most common

and generally utilize a dam to store water at an increased elevation. The use of a dam toimpound water also provides the capability of storing water during rainy periods and

releasing it during dry periods. This results in the consistent and reliable production of


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Electricity, able to meet demand. Heads for this type of power plant may be greater than

1000 m. Most large hydroelectric facilities are of the high head variety. High head plants

with storage are very valuable to electric utilities because they can be quickly adjusted to

meet the electrical demand on a distribution system.

2.5 HYDRO ELECTRIC POWER FOR THE NATION

Although most energy in the United States is produced by fossil fuel and

nuclear power plants, hydroelectricity is still important to the Nation, as about 10 percent

of total power is produced by hydroelectric plants. Nowadays, huge power generators are

placed inside dams. Water flowing through the dams spin turbine blades (made out of

metal instead of leaves) which are connected to generators. Power is produced and is sent

to homes and businesses. Producing electricity using hydroelectric power has some

advantages over other power producing methods. Let's do a quick comparison:

Reservoir construction is "drying up"

Gosh, hydroelectric power sounds great -- so why don't we use it to produce

all of our power? Mainly because you need lots of water and a lot of land where you can

build a dam and reservoir, which all takes a LOT of money, time, and construction. In

fact, most of the good spots to locate hydro plants have already been taken. In the early

part of the century hydroelectric plants supplied a bit less than one-half of the nation's

power, but the number is down to about 10 percent today. The trend for the future will

probably be to build small-scale hydro plants that can generate electricity for a single

community.

2.6 ENVIRONMENTAL IMPACTS

Hydro-electric power plants have many environmental impacts, some of

which are just beginning to be understood. These impacts, however, must be weighed

against the environmental impacts of alternative sources of electricity. Until recently there

was an almost universal belief that hydro power was a clean and environmentally safe

method of producing electricity. Hydro-electric power plants do not emit any of the

standard atmospheric pollutants such as carbon dioxide or sulfur dioxide given off by

fossil fuel fired power plants. In this respect, hydro power is better than burning coal, oil

or natural gas to produce electricity, as it does not contribute to global warming or acid


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rain. Similarly, hydro-electric power plants do not result in the risks of radioactive

contamination associated with nuclear power plants.

A few recent studies of large reservoirs created behind hydro dams have

suggested that decaying vegetation, submerged by flooding, may give off quantities of

greenhouse gases equivalent to those from other sources of electricity. If this turns out to

be true, hydro-electric facilities such as the James Bay project in Quebec that flood large

areas of land might be significant contributors to global warming. Run of the river hydro

plants without dams and reservoirs would not be a source of these greenhouse gases.

The most obvious impact of hydro-electric dams is the flooding of vast areas of land,

much of it previously forested or used for agriculture. The size of reservoirs created can

be extremely large. The La Grande project in the James Bay region of Quebec has already

submerged over 10,000 square kilometers of land; and if future plans are carried out, the

eventual area of flooding in northern Quebec will be larger than the country of

Switzerland. Reservoirs can be used for ensuring adequate water supplies, providing

irrigation, and recreation; but in several cases they have flooded the homelands of native

peoples, whose way of life has then been destroyed. Many rare ecosystems are also

threatened by hydro-electric development.Large dams and reservoirs can have other impacts on a watershed.

Damming a river can alter the amount and quality of water in the river downstream of the

dam, as well as preventing fish from migrating upstream to spawn. These impacts can be

reduced by requiring minimum flows downstream of a dam, and by creating fish ladders

which allow fish to move upstream past the dam. Silt, normally carried downstream to the

lower reaches of a river, is trapped by a dam and deposited on the bed of the reservoir.

This silt can slowly fill up a reservoir, decreasing the amount of water which can be

stored and used for electrical generation. The river downstream of the dam is also

deprived of silt which fertilizes the river's flood-plain during high water periods.

Bacteria present in decaying vegetation can also change mercury, present in rocks

underlying a reservoir, into a form which is soluble in water. The mercury accumulates in

the bodies of fish and poses a health hazard to those who depend on these fish for food.

The water quality of many reservoirs also poses a health hazard due to new forms of

bacteria which grow in many of the hydro rivers. Therefore, run of the river type hydro

plants generally have a smaller impact on the environment.


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2.7 DIFFERENT CLASSIFICATIONS OF HYDRAULIC

POWER PLANTS

1. Depending upon Capacity to generate power:

Size unit size Installation

Micro upto 100 kW 100 kW

Mini 101 to 1000 kW 2000 kW

Small 1001 to 6000 kW 15000 kW

2. Depending on head:

Ultra low head: Below3 meters,

Low head : Less than 30 meters,

Medium head: Between 30 to 75 meters,

High head : Above 75 meters,

2.8 SELECTION OF SITES FOR HYDRO POWER PLANT

1. Large quantity of water at a reasonable head should be available

2. The site should provide strong and high mountains on the two sides of the river

reservoir with minimum gap for economical dam construction.

3. The rainfall should be sufficient to maintain desired water level in the reservoir

throughout the year.

4. The catchments area for the reservoir to collect rainwater should be large.

5. There should not be any possibility of leakage of water in future.

6. The site should have firm rock for foundation.

2.9BASIC COMPONENTS OF A HYDRO ELECTRIC

POWER PLANT

The basic and common components of a hydroelectric power plant are given below:

a) Diversion and intake

b) Desilting chamber

c) Water conducting system

d) Balancing reservoir

e) Surge tank (if necessary)


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f) Penstock

g) Power house: turbine, generator, protection and control equipment, dewatering,

drainage system, auxiliary, power system, grounding, emergency and standby power

system, lighting and ventilation Tail race channel.

Diversion structure:

The diversion structure provided should be simple in construction as well as

economical. It should involve minimum maintenance. Depending upon the type of river

bed the diversion structure may be of two-type viz. Boulder weir and Trench type weir. It

is usually constructed in re-enforced concrete or masonry.

Water conductor system:

Water conducting system is the very important component of hydro-power plant. The

type of water conductor system depends on the site conditions and the materials available.

The design of the water conduction system should ensure minimum head loss, adequate

velocity of flow so that silt does not settle down. The material of construction should be

such that loss due to seepage is also minimized. The most commonly used channel

section is trapezoidal.

Desalting tank :

Desilting tank is provided usually in the initial reaches of water conductor to trap the

suspended silt load and pebbles etc ; so as to minimize the erosion damages to the turbine

runner. The size of silt particles to be trapped for medium head power stations is from 0.2

to 0.5 mm and for high head it is from 0.1 to 0.2 mm. The depth of tank may be kept

between 1.5 to 4 m. The horizontal flow velocity should not exceed 0.4 to 0.6 m/s.

Layout of hydro power plants:

The layout of hydro power plants envisages positioning of the various components of the

plant to insure optimum use of available space for its efficient and convenient erection,

operation and maintenance.

Power house

The power is positioned at the toe of the concrete masonry dam where the

suitable rock to lay foundation is available each turbine is fed by a separate penstock

which is embedded inside the non-overflow section of the dam. The power house

separated from the dam expansion joints. With a view to minimize the fluctuations in the


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tail water level. Especially due to ski jump trajectory, the power go use maybe located

further downstream and fed through a tunnel branching into individual penstocks near the

powerhouse.

The powerhouse may be located at the underground, led through

pressure shafts or pressure tunnels with surge tank. The power house may be located

below the ski jump bucket itself. In the case of earth and rock fill dams, the power house

is separated from the dam founded on suitable location and fed by penstock s generally

taken out from a tunnel earlier used as diversion tunnel. Sometimes penstock may be laid

in trench excavated below the dam buried in concrete.

TYPES OF POWERHOUSES:

Surfaces power house:

It is the best choice when sufficient area is available to accommodate the powerhouse

within economical and convenient excavation. The there are three types of surface

powerhouse depending on superstructure are outdoor, semi out door, indoor types

Semi-underground power house

The surface with setting of turbines below the minimum tail water level may involve

substantial excavation and then backfilling with concrete to facilitate construction of high

retaining walls for protections against floods. In this type vertical shafts are driven in rock

for housing part of draft tube, spiral casings turbines and generators.

Submersible powerhouse:

In this type of power plant which is incorporated in the body of spillway beneath the

crest. The head water elevation is incorporated in the body of spillway beneath the crest.

The head water elevation is maintained with the help of vertical lift crest gates. It has

advantages of economy because separate powerhouse structure is avoided in this

arrangement.

2.10 HYDRO-ELECTRIC 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; whereas a hydroelectric plant uses falling water to

turn the turbine.


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FRANCIS TURBINE

The theory is to build a dam on a large river that has a large drop in elevation

(there are not many hydroelectric plants in Kansas or Florida). 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 mine. 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.

The Francis turbine is a reaction turbine, which means that the working fluid

changes pressure as it moves through the turbine, giving up its energy. A casement is

needed to contain the water flow. The turbine is located between the high-pressure water

source and the low-pressure water exit, usually at the base of a dam.

The inlet is spiral shaped. Guide vanes direct the water tangentially to the turbine

wheel, known as a runner. This radial flow acts on the runner's vanes, causing the runner

to spin. The guide vanes (or wicket gate) may be adjustable to allow efficient turbine

operation for a range of water flow conditions.

As the water moves through the runner, its spinning radius decreases, further acting on

the runner. For an analogy, imagine swinging a ball on a string around in a circle; if the

string is pulled short, the ball spins faster due to the conservation of angular momentum.

This property, in addition to the water's pressure, helps Francis and other inward-flow

turbines harness water energy efficiently.


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Fig 2.1

IMPULSE TURBINES: THE PELTON WHEEL

The impulse turbine is very easy to understand. A nozzle transforms water

under a high head into a powerful jet. The momentum of this jet is destroyed by striking

the runner, which absorbs the resulting force. If the velocity of the water leaving the

runner is nearly zero, all of the kinetic energy of the jet has been transformed intomechanical energy, so the efficiency is high.

A practical impulse turbine was invented by Lester A. Pelton (1829-1908) in

California around 1870. There were high-pressure jets there used in placer mining, and a

primitive turbine called the hurdy-gurdy, a mere rotating platform with vanes, had been

used since the '60's, driven by such jets. Pelton also invented the split bucket, now

universally used, in 1880. Pelton is a trade name for the products of the company he

originated, but the term is now used generically for all similar impulse turbines.

The water flows along the tangent to the path of the runner. Nozzles direct forceful

streams of water against a series of spoon-shaped buckets mounted around the edge of a

wheel. As water flows into the bucket, the direction of the water velocity changes to

follow the contour of the bucket. When the water-jet contacts the bucket, the water exerts

pressure on the bucket and the water is decelerated as it does a "u-turn" and flows out the

other side of the bucket at low velocity. In the process, the water's momentum is

transferred to the turbine. This "impulse does work on the turbine. For maximum power

and efficiency, the turbine system is designed such that the water-jet velocity is twice the


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velocity of the bucket. A very small percentage of the water's original kinetic energy will

still remain in the water; however, this allows the bucket to be emptied at the same rate it

is filled, (see conservation of mass), thus allowing the water flow to continue

uninterrupted. Often two buckets are mounted side-by-side, thus splitting the water jet in

half (see photo). This balances the side-load forces on the wheel, and helps to ensure

smooth, efficient momentum transfer of the fluid jet to the turbine wheel.

Because water and most liquids are nearly incompressible, almost all of the available

energy is extracted in the first stage of the hydraulic turbine. Therefore, Pelton wheels

have only one turbine stage, unlike gas turbines that operate with compressible fluid

Fig. 2.2

REACTION TURBINES: THE LAWN SPRINKLER

By contrast with the impulse turbine, reaction turbines are difficult to

understand and analyze, especially the ones usually met with in practice. The modest

lawn sprinkler comes to our aid, since it is both a reaction turbine, and easy to understand.

It will be our introduction to reaction turbines. In the impulse turbine, the pressure change

occurred in the nozzle, where pressure head was converted into kinetic energy. There was

no pressure change in the runner, which had the sole duty of turning momentum change

into torque. In the reaction turbine, the pressure change occurs in the runner itself at the


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same time that the force is exerted. The force still comes from rate of change of

momentum, but not as obviously as in the impulse turbine.

Underground sprinklers function through means of basic electronic and hydraulic

technology. This valve and all of the sprinklers that will be activated by this valve are

known as a zone. Upon activation, the solenoid, which sits on top of the valve is

magnetized lifting a small stainless steel plunger in its center. By doing this, the activated

(or raised) plunger allows air to escape from the top of a rubber diaphragm located in the

center of the valve. Water that has been charged and waiting on the bottom of this same

diaphragm now has the higher pressure and lifts the diaphragm. This pressurized water is

then allowed to escape down stream of the valve through a series of pipes, usually made

of PVC (higher pressure commercial systems) or polyethylene pipe (for typically lower

pressure residential systems). At the end of these pipes and flush to ground level

(typically) are pre measured and spaced out sprinklers. These sprinklers can be fixed

spray heads that have a set pattern and generally spray between 1.5-2m (715 ft.), full

rotating sprinklers that can spray a broken stream of water from 6-12m (2040 ft.), or

small drip emitters that release a slow, steady drip of water on more delicate plants such

as flowers and shrubs. use of indegenous materials also recommended..The duty of the lawn sprinkler is to spread water; its energy output as

a turbine serves only to move the sprinkler head. It is a descendant of Hero's aeolipile, the

rotating globe with two bent jets that was quite a sensation in ancient times, though this

worked with steam, not water. The lawn sprinkler seems directly descended from Rev.

Robert Barker's proposed mill of 1740. He used two jets at right angles to the radius. A

later improvement fed water from below to balance the weight of the runner and reduce

friction. Barker's mills only appeared as models, and were never commercially offered.

The flow of water in a lawn sprinkler is radially outward. Water under pressure is

introduced at the centre, and jets of water that can cover the area necessary issue from the

ends of the arms at zero gauge pressure. The pressure decrease occurs in the sprinkler

arms. Though the water is projected at an angle to the radius, the water from an operating

sprinkler moves almost along a radius. If you have such a sprinkler, by all means observe

it in action. The jets do not impinge on a runner; in fact, they are leaving the runner, so

their momentum is not converted into force as in the impulse turbine. The force on the

runner must act in reaction to the creation of the momentum instead, which is, of course,

the origin of the name of the reaction turbine.


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2.11 TOTAL ANNUAL COST OF HYDRO POWER

PROJECT

Total annual cost of hydro power project consists of three elements:

1. Fixed charges it includes fixed charges on plant interest taxes insurances depreciation

and obsolescence

2. Operation and maintenance cost

It includes operating cost, fuel cost, supervisory, labor maintenance, repair and

miscellaneous expenses .the annual operation and maintenance cost is roughly

proportional to the capacity of plant and the number of unit installed. The annualmaintenance cost is usually taken as 1.5% of capital cost.

3. Transmission cost

It covers the cost of transmission facilities to connect the power generated

to the system load."Low head" hydroelectric plants are power plants which generally

utilize heads of only a few meters or less. Power plants of this type may utilize a low dam

or weir to channel water, or no dam and simply use the "run of the river". Run of the river

generating stations cannot store water, thus their electric output varies with seasonalflows of water in a river. A large volume of water must pass through a low head hydro

plant's turbines in order to produce a useful amount of power. Hydro-electric facilities

with a capacity of less than about 25 MW (1 MW = 1,000,000 Watts) are generally

referred to as "small hydro", although hydro-electric technology is basically the same

regardless of generating capacity.

"Pumped Storage" is another form of hydro-electric power. Pumped storage

facilities use excess electrical system capacity, generally available at night, to pump water

from one reservoir to another reservoir at a higher elevation. During periods of Peak

electrical demand, water from the higher reservoir is released through turbines to the

lower reservoir, and electricity is produced (Figure 2). Although pumped storage sites are

not net producers of electricity - it actually takes more electricity to pump the water up

than is recovered when it is released - they are a valuable addition to electricity supply

systems. Their value is in their ability to store electricity for use at a later time when peak

demands are occurring. Storage is even more valuable if intermittent sources of electricity

such as solar or wind are hooked into a system.


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BULB-TYPE GENERATORS

GE has a strong background in building large slow-speed horizontal synchronous

machines of this type. In such applications, our experience focuses on air-gap stability,

distortion control, unbalanced magnetic pull, ventilation, frame stiffness and seal design.

CONVENTIONAL GENERATORS

Designed for all types of vertical axis applications, conventional generators are installed

in locations having a variety of head and flow conditions.

STRAFLO (RIM-TYPE) GENERATORS

These types of generators are designed for straight-flow turbine system applications to

harness tidal flow effectively for the production of electric power as well as for low head

applications.

MOTORS FOR PUMPED STORAGE

Many utilities lower system costs by adding pumped storage capacity. In addition to

supplying low cost peaking capacity, pumped storage provides spinning reserve to the

system. GE has supplied more than 50 units with a total capacity of over 7,400,000 kVA

(7,000,000 kW).

2.12 FUTURE DIRECTIONS FOR THE HYDROELECTRIC

INDUSTRY

The hydroelectric industry has been termed "mature" by some who charge

that the technical and operational aspects of the industry have changed little in the past 60

years. Recent research initiatives counter this label by establishing new concepts for

design and operation that show promise for the industry. A multi-year research project is

presently testing new turbine designs and will recommend a final turbine blade

configuration that will allow safe passage of more than 98 percent of the fish that are

directed through the turbine. The DOE also recently identified more than 30 million

kilowatts of untapped hydroelectric capacity that could be constructed with minimal

environmental effects at existing dams that presently have no hydroelectric generating

facilities, at existing hydroelectric projects with unused potential, and even at a number of

sites without dams. Follow-up studies will assess the economic issues associated with this

untapped hydroelectric resource. In addition, studies to estimate the hydroelectricpotential of undeveloped, small capacity, dispersed sites that could supply electricity to

adjacent areas without connecting to a regional electric transmission distribution system


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are proceeding. Preliminary results from these efforts have improved the visibility of

hydroelectric power and provide indications that the hydroelectric power industry will be

vibrant and important to the country throughout the next century.

The theoretical size of the worldwide hydro power is about four times

greater than that which has been exploited at this time. The actual amount of electricity

which will ever be generated by hydro power will be much less than the theoretical

potential. This is due to the environmental concerns outlined above, and economic

constraints. Much of the remaining hydro potential in the world exists in the developing

countries of Africa and Asia. Harnessing this resource would require billions of dollars,

because hydro-electric facilities generally have very high construction costs. In the past,

the World Bank has spent billions of foreign aid dollars on huge hydro-electric projects in

the third world. Opposition to hydro power from environmentalists and native people, as

well as new environmental assessments at the World Bank will restrict the amount of

money spent on hydro-electric power construction in the developing countries of the

world.

In North-America and Europe, a large percentage of hydro power

potential has already been developed. Public opposition to large hydro schemes willprobably result in very little new development of big dams and reservoirs. Small scale

and low head hydro capacity will probably increase in the future as research on low head

turbines, and standardized turbine production, lowers the costs of hydro-electric power at

sites with Companies have to dig up the Earth or drill wells to get the coal, oil, and gasor

nuclear power plants there are waste-disposal problems

New computerized control systems and improved turbines may allow more

electricity to be generated from existing facilities in the future. As well, many small hydro

electric sites were abandoned in the 1950's and 60's when the price of oil and coal was

very low, and their environmental impacts unrealized. Increased fuel prices in the future

could result in these facilities being refurbished.

2.13 CASE STUDY EXAMPLE

KOYNA DAM, KOYNA NAGAR.

Koyna Dam is one of the largest dams in Maharashtra, India. It is located in

Koyna Nagar, nestled in the Western Ghats on the state highway between Chiplun and


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Karad, Maharashtra. The dam supplies water to western Maharashtra as well as cheap

hydroelectric power to the neighbouring areas with a capacity of 1,920 MW. The Koyna

project is actually composed of four dams, with the Koyna dam having the largest

catchment area.

The catchment area dams the Koyna River and forms a huge lake the

Shivsagar Lake whose length is 50 kilometres. Completed in 1963, it is one of the largest

civil engineering projects commissioned after Indian independence. The Koyna electricity

project is run by the Maharashtra State Electricity Board. Most of the generators are

located in excavated caves a kilometre deep, inside the heart of the surrounding hills.

The dam is blamed for the spate of earthquakes in the recent past. In 1967 a devastating

earthquake almost razed the dam, with the dam developing major cracks. Geologists are

still uncertain if the Koyna Dam is responsible for the spate in seismic activity.

Koyna Dam is one of the largest damsinMaharashtra,India. It is located in Koyna Nagar,

nestled in the Western Ghats on the state highway between Chiplun and

Karad,Maharashtra. The dam supplies water to western Maharashtra as well as cheap

Hydro electric power to the neighbouring areas with a capacity of 1,920 MW. The Koyna

project is actually composed of four dams, with the Koyna dam having the largestcatchment area.

The catchment area dams the Koyna River and forms a huge lake the

Shivsagar Lake whose length is 50 kilometres. Completed in 1963, it is one of the largest

civil engineering projects commissioned after Indian independence. The Koyna electricity

project is run by theMaharashtra State Electricity Board. Most of the generators are

located in excavated cavesa kilometre deep, inside the heart of the surrounding hills.The

dam is blamed for the spate of earthquake in the recent past. In 1967 a devastating

earthquake almost razed the dam, with the dam developing major cracks. Geologists are

still uncertain if the Koyna Dam is responsible for the spate in seismic activity.

Statistics

Storage:

o Gross storage: 98.78 TMC

o Live: 93.65 TMC

o Dead: 5.125 TMC

Length: 1807.22 m


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Height: 85.35 m

Year of completion: 1963

The Koyna Dam in Maharashtra

The resovoir behind the dam is 50 km in length.

Gravitational potential energy is stored in the water above the dam. Because of the great

height of the water, it will arrive at the turbines at high pressure, which means that we can

extract a great deal of energy from it. The water then flows away downriver as normal.

In mountainous countries such as Switzerland and New Zealand, hydro-electric power

provides more than half of the country's energy needs.

An alternative is to build the station next to a fast-flowing river. However with this

arrangement the flow of the water cannot be controlled, and water cannot be stored for

later use.

Hydro-electric power stations can produce a great deal of power very cheaply.

When it was first built, the huge "Hoover Dam", on the Colorado river, supplied much of

the electricity for the city of Las Vegas; however now Las Vegas has grown so much, the

city gets most of its energy from other sources.There's a good explanation of how hydropower works at Although there are many suitable sites around the world, hydro-electric

dams are very expensive to build. However, once the station is built, the water comes free

of charge, and there is no waste or pollution.

1962 - 1963

Height of dam: 103 meters

Water storage: 2,797.400 km

Volume of dam: 1,555.000 m

Width of dam: 808 m

Slope at water side: 24:1

Length of 60 km

In a major technological breakthrough, the engineers of Koyna hydroelectric

project today successfully performed the `lake tapping' operations at Shivaji Sagar

reservoir of the dam. This operation or `lake tapping' using Norwegian technology will

pave the way for the commissioning of the 1,000 MW stage four of the Koyna

hydroelectric project, which would take total generation capacity to 1,920 MW by this

year end.


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Enthusiasm reigned on the banks of Shivaji Sagar reservoir, as people from

neighbouring villages flocked the lake to witness the `lake tapping', the first of its kind in

Asia.

Standing on the hilly terrain of the Koyna backwater, people were all ears to the

announcements made by Shrikant Huddar, chief engineer of the Koyna Hydel project.

And as Huddar instructed his subordinates to switch on the Konsbergs underwater

cameras, the countdown for the million dollar blast had begun.

Beginning from 10, Huddar launched his countdown and just after he had

announcedzero, within a fraction of a second after Chief Minister Narayan Rane had

switched knobs activating the blastings, hundreds of people felt waves of tremors passing

under their feet. Suddenly, a mushroom flower-like cloud of water erupted from Shivaji

Sagar reservoir, and ripples after ripples hit the banks. Soon after the ripples hit the banks,

villagers standing on the banks lifted the water from the reservoir and gently applied it to

their foreheads. No one could hear the sound of the blasts, but they had certainly felt it

deep inside their hearts. Certainly it was a moment to cherish.

Planned for 1000 MW power generation, the fourth stage of Koyna hydro

electric project, envisages that the water will be tapped by piercing the Koyna reservoir,following which it will be carried through a 4.25 km-long head race tunnel into the

underground power house.

Speaking on the occasion after the blasts had been conducted, ministers

Eknath Khadase,Anna Dange, Harshvardhan Patil, Deputy Chief Minister Gopinath

Munde and Chief Minister Narayan Rane were all praise for the State irrigation

department. While Irrigation Minister Khadse said such blasts could be replicated in

future to generate more power, Rural Development Minister Anna Dange actually coined

a couplet describing the event.Munde, who also holds the energy portfolio, expressed his

gratitude to irrigation department for inviting him to witness the `lake tapping'. He also

said the `event' was a major leap towards the State Government's dream to be self-

sufficient in power generation.

At present there is a shortage of nearly 1000-1500 MW of power in the State.

This difference will be reduced after the Koyna fourth stage starts generating 1000 MW

power. Chief Minister was also all praise for the irrigation department and said this

development would go a long way in providing excess power for the State.

The Koyana dam is at Koynanagar in Patan tehsil of Satara district in theSahyadaris. Its


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Shivaji Sagar reservoir has a capacity of 2,797 million cubic metres of water. The Rs

1,300 crore stage-four project is a World Bank funded project having commenced in

1992.

2.14 MAN AND ENERGY

Man has needed and used energy at an increasing rate for its sustenance and

well being ever since he came on the earth a few million years ago. Primitive man

required energy primarily in the form of food. He derived this by eating plants or

animals, which he hunted. Subsequently he discovered fire and his energy needs

increased as he started to make use of wood and other bio mass to supply the energy

needs for cooking as well as agriculture. He added a mew dimension to the use of energy

by domesticating and training animals to work for him.

With further demand for energy, man began to use the wind for sailing ships

and for driving windmills, and the force of failing water to turn water wheels. Till this

time, it would not be wrong to say that the sun was supplying all the energy needs of man

either directly or indirectly and that man was using only renewable sources of energy.The

industrial revolution, which began with the discovery of the steam engine (AD 1700),

brought about great many changes. For the first time, man began to use a new source of

energy, viz. coal, in large quantities. A little later, the internal combustion engine was

invented (AD1870) and the other fossil fuels, oil and natural combustion engine

extensively. The fossil fuel era of using non-renewable sources had begun and energy

was now available in a concentrated form. The invention of heat engines and then use of

fossil fuels made energy portable and introduced the much needed flexibility in mansmovement.For the first time, man could get the power of a machine where he required it

and was not restricted to a specific site like a fast-running stream for running a water

wheel or a windy hill for operating a windmill. This flexibility was enhanced with the

discovery of electricity the development of central power generating stations using either

fossil fuels or waterpower.

A new source of energy-nuclear energy-came on the scene after the Second

World War The first large nuclear power station was commissioned about 40 years ago,and already, nuclear energy is providing a small but significant amount of the energy

requirements of many countries. Thus today, every country draws its energy needs from a


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variety of sources. We can broadly categorize these sources as commercial and

noncommercial. The commercial sources include the fossil fuels (coal, oil and natural

gas), hydroelectric power and nuclear power, while the non-commercial sources include

wood, animal wastes, geothermal energy and agricultural wastes.

In an industrialized country like USA, most of the energy requirements are

meant from commercial sources, while in an industrially less developed country like

India, the use of commercial and noncommercial sources is about equal. In the past few

years, it has become obvious that fossil fuel resources are fast depleting and that the fossil

fuel era is gradually coming to an end. This is particularly true for oil and natural gas. It

will be use full there fore to first examine the rates of consumption of the different

sources of energy and to give some indication of the reserves available this study will be

done for the world as a whole and then for India in particular with the help of these

figures it will be possible to form estimates of the time periods for which the existing

source will be available. The need for alternative energy options will thus be established

and these options will then be briefly described.

Before passing on to these topics, it is worth noting that while mans large-

scale use of commercial energy has led to a better quality of life it has also created manyproblems. Perhaps the most serious of these is the harmful effect on the environment.

The combustion of the fossil fuel has caused serious air pollution problems in many areas

because of the localized release of large amounts of harmful gases into the atmosphere. It

has also resulted in the phenomenon of global warning, which is now a matter of great

concern. Similarly the releases of large amounts of waste heat from power plants have

caused thermal pollution in lakes and rivers leading to the destruction of many forms of

plants and animals life.In the case of nuclear power plants there is also concern over the

possibility of radio activity being released into the atmosphere in the event of an accident

and over the long term problems of disposal of radioactive wastes from these plants. The

gravity of most of these environmental problems had not really been foreseen. Now

however, as man embarks on the search for alternative sources of energy, it is clear that

the would do well to keep the environmental in mind.


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CHAPTER 3

COMPONENTS AND DESCRIPTION

3.1 PHYSICAL SETUP

Water Pump

Battery

Inverter

D.C Generator

Lighting Load

3.1.1 WATER PUMP:-

The single phase induction motor is coupled with the vacuum pump impeller with

suitable arrangement.

It is found to drive the roller shaft which fixed on the end of the frame structure. The free

end of the shaft in the motor a large pulley is found around which the belt runs. The other

specification about the motor is discussed in design part of the machine.

3.1.2 BATTERIES

3.1.2.1 INTRODUCTION:

In isolated systems away from the grid, batteries are used for storage of excess

solar energy converted into electrical energy. The only exceptions are isolated sunshine

load such as irrigation pumps or drinking water supplies for storage.In fact for small units

with output less than one kilowatt. Batteries seem to be the only technically and

economically available storage means. Since both the photo-voltaic system and batteries

are high in capital costs. It is necessary that the overall system be optimized with respect


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to available energy and local demand pattern. To be economically attractive the storage

of solar electricity requires a battery with a particular combination of properties:

(1) Low cost

(2) Long life

(3) High reliability

(4) High overall efficiency

(5) Low discharge

(6) Minimum maintenance

(A) Ampere hour efficiency

(B) Watt hour efficiency

We use lead acid battery for storing the electrical energy from the solar panel for

lighting the street and so about the lead acid cells are explained below.

3.1.2.2 LEAD-ACID WET CELL:

Where high values of load current are necessary, the lead-acid cell is the type most

commonly used. The electrolyte is a dilute solution of sulfuric acid (HSO). In the

application of battery power to start the engine in an auto mobile, for example, the load

current to the starter motor is typically 200 to 400A. One cell has a nominal output of

2.1V, but lead-acid cells are often used in a series combination of three for a 6-V battery

and six for a 12-V battery.

A battery is a device that converts chemical energy directly to electrical energy.It

consists of a number of voltaic cells; each voltaic cell consists of two half-cells connected

in series by a conductive electrolyte containing anions and cations. One half-cell includes

electrolyte and the electrode to which anions (negatively charged ions) migrate, i.e., the

anode or negative electrode; the other half-cell includes electrolyte and the electrode to

which cations (positively charged ions) migrate, i.e., the cathode or positive electrode. In

the redox reaction that powers the battery, cations are reduced (electrons are added) at

the cathode, while anions are oxidized (electrons are removed) at the anode.The

electrodes do not touch each other but are electrically connected by the electrolyte. Some


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cells use two half-cells with different electrolytes. A separator between half-cells allows

ions to flow, but prevents mixing of the electrolytes.

Each half-cell has an electromotive force (or emf), determined by its ability to drive

electric current from the interior to the exterior of the cell. The net emf of the cell is the

difference between the emfs of its half-cells, as first recognized by Volta. Therefore, if

the electrodes have emfs and , then the net emf is ; in other words, the net

emf is the difference between the reduction potentials of the half-reactions.

The electrical driving force or across the terminals of a cell is known as the

terminal voltage (difference) and is measured in volts. The terminal voltage of a cell that

is neither charging nor discharging is called the open-circuit voltage and equals the emf of

the cell. Because of internal resistance, the terminal voltage of a cell that is discharging is

smaller in magnitude than the open-circuit voltage and the terminal voltage of a cell that

is charging exceeds the open-circuit voltage. An ideal cell has negligible internal

resistance, so it would maintain a constant terminal voltage of until exhausted, then

dropping to zero. If such a cell maintained 1.5 volts and stored a charge of one coulomb

then on complete discharge it would perform 1.5 joule of work. In actual cells, the

internal resistance increases under discharge, and the open circuit voltage also decreases

under discharge. If the voltage and resistance are plotted against time, the resulting graphs

typically are a curve; the shape of the curve varies according to the chemistry and internal

arrangement employed.

As stated above, the voltage developed across a cell's terminals depends on the energy

release of the chemical reactions of its electrodes and electrolyte. Alkaline and zinccarbon cells have different chemistries but approximately the same emf of 1.5 volts;

likewise NiCd and NiMH cells have different chemistries, but approximately the same

emf of 1.2 volts. On the other hand the high electrochemical potential changes in the

reactions of lithium compounds give lithium cells emfs of 3 volts or more.

The lead acid cell type is a secondary cell or storage cell, which can be recharged.

The charge and discharge cycle can be repeated many times to restore the output voltage,

as long as the cell is in good physical condition. However, heat with excessive charge

and discharge currents shortends the useful life to about 3 to 5 years for an automobile


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battery. Of the different types of secondary cells, the lead-acid type has the highest

output voltage, which allows fewer cells for a specified battery voltage.

3.1.2.3 CONSTRUCTION:

Inside a lead-acid battery, the positive and negative electrodes consist of a group

of plates welded to a connecting strap. The plates are immersed in the electrolyte,

consisting of 8 parts of water to 3 parts of concentrated sulfuric acid. Each plate is a grid

or framework, made of a lead-antimony alloy. This construction enables the active

material, which is lead oxide, to be pasted into the grid. In manufacture of the cell, a

forming charge produces the positive and negative electrodes. In the forming process, the

active material in the positive plate is changed to lead peroxide (pbo). The negative

electrode is spongy lead (pb).

The construction parts of battery are shown in figure.


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Fig 3.1


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3.1.2.4 CHEMICAL ACTION:

Sulfuric acid is a combination of hydrogen and sulfate ions. When the cell

discharges, lead peroxide from the positive electrode combines with hydrogen ions to

form water and with sulfate ions to form lead sulfate. Combining lead on the negative

plate with sulfate ions also produces he sulfate. There fore, the net result of discharge is

to produce more water, which dilutes the electrolyte, and to form lead sulfate on the

plates.

As the discharge continues, the sulfate fills the pores of the grids, retarding

circulation of acid in the active material. Lead sulfate is the powder often seen on the

outside terminals of old batteries. When the combination of weak electrolyte and

sulfating on the plate lowers the output of the battery, charging is necessary.

On charge, the external D.C. source reverses the current in the battery. The reversed

direction of ions flows in the electrolyte result in a reversal of the chemical reactions.

Now the lead sulfates on the positive plate reactive with the water and sulfate ions to

produce lead peroxide and sulfuric acid. This action re-forms the positive plates and

makes the electrolyte stronger by adding sulfuric acid. At the same time, charging

enables the lead sulfate on the negative plate to react with hydrogen ions; this also forms

sulfuric acid while reforming lead on the negative plate to react with hydrogen ions; this

also forms currents can restore the cell to full output, with lead peroxide on the positive

plates, spongy lead on the negative plate, and the required concentration of sulfuric acid

in the electrolyte.

The chemical equation for the lead-acid cell is

charge

Pb + pbO + 2HSO 2pbSO + 2HO

Discharge

On discharge, the pb and pbo combine with the SO ions at the left side of the

equation to form lead sulfate (pbSO) and water (HO) at the right side of the equation.

One battery consists of 6 cells, each have an output voltage of 2.1V, which are connectedDept. of MechanicalEngg. ,MVJCE

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in series to get an voltage of 12V and the same 12V battery is connected in series, to get

an 24 V battery. They are placed in the water proof iron casing box.

3.1.2.5 CARING FOR LEAD-ACID BATTERIES:

Always use extreme caution when handling batteries and electrolyte. Wear

gloves, goggles and old clothes. Battery acid will burn skin and eyes and destroy

cotton and wool clothing.The quickest way of ruin lead-acid batteries is to discharge them

deeply and leave them stand dead for an extended period of time. When they

discharge, there is a chemical change in the positive plates of the battery.They change

from lead oxide when charge out lead sulfate when discharged. If they remain in the lead

Sulfate State for a few days, some part of the plate dose not returns to lead oxide when

the battery is recharged. If the battery remains discharge longer, a greater amount of the

positive plate will remain lead sulfate. The parts of the plates that become sulfate no

longer store energy. Batteries that are deeply discharged, and then charged partially on a

regular basis can fail in less then one year.Check your batteries on a regular basis to be

sure they are getting charged. Use a hydrometer to check the specific gravity of your lead

acid batteries. If batteries are cycled very deeply and then recharged quickly, the specific

gravity reading will be lower than it should because the electrolyte at the top of the

battery may not have mixed with the charged electrolyte. Check the electrolyte level in

the wet-cell batteries at the least four times a year and top each cell of with distilled

water. Do not add water to discharged batteries. Electrolyte is absorbed when batteries

are very discharged. If you add water at this time, and then recharge the battery,

electrolyte will overflow and make a mess.Keep the top of your batteries clean and checkthat cables are tight. Do not tighten or remove cables while charging or discharging. Any

spark around batteries can cause a hydrogen explosion inside, and ruin one of the cells,

and you.On charge, with reverse current through the electrolyte, the chemical action is

reversed. Then the pb ions from the lead sulfate on the right side of the equation re-form

the lead and lead peroxide electrodes. Also the SO ions combine with H ions from the

water to produce more sulfuric acid at the left side of the equation.

Leadacid batteries lose the ability to accept a charge when discharged for too long due to

sulfation, the crystallization of lead sulfate. They generate electricity through a doubleDept. of MechanicalEngg. ,MVJCE

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sulfate chemical reaction. Lead and lead dioxide, the active materials on the battery's

plates, react with sulfuric acid in the electrolyte to form lead sulfate. The lead sulfate first

forms in a finely divided, amorphous state, and easily reverts to lead, lead dioxide and

sulfuric acid when the battery recharges. As batteries cycle through numerous discharges

and charges, some lead sulfate is not recombined into electrolyte and slowly converts to a

stable crystalline form that no longer dissolves on recharging. Thus, not all the lead is

returned to the battery plates, and the amount of usable active material necessary for

electricity generation declines over time.

Sulfation occurs in all leadacid batteries during normal operation. It impedes recharging;

sulfate deposits ultimately expand, cracking the plates and destroying the battery.

Eventually so much of the battery plate area is unable to supply current that the battery

capacity is greatly reduced. In addition, the sulfate portion (of the lead sulfate) is not

returned to the electrolyte as sulfuric acid. The large crystals physically block the

electrolyte from entering the pores of the plates. Sulfation can be avoided if the battery is

fully recharged immediately after a discharge cycle. A white coating on the plates may be

visible (in batteries with clear cases, or after dismantling the battery). Batteries that are

sulfated show a high internal resistance and can deliver only a small fraction of normal

discharge current.

Sulfation also affects the charging cycle, resulting in longer charging times, less efficient

and incomplete charging, and higher battery temperatures.

The process can often be at least partially reversed by a desulfation technique called pulse

conditioning, in which short but powerful current surges are repeatedly sent through the

damaged battery. Over time, this procedure tends to break down and dissolve the sulfate

crystals, restoring some capacity.

Desulfation is the process of reversing the sulfation of a lead-acid battery. Desulfation is

achieved by high current pulses produced between the terminals of the battery. This

technique, also calledpulse conditioning, breaks down the sulfate crystals that are formed

on the battery plates. Short high current pulses tend to work best. Electronic circuits are

used to regulate the pulses of different widths and frequency of high current pulses. These

can also be used to automate the process since it takes a long period of time to desulfate a


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battery fully. Battery chargers designed for desulfating lead-acid batteries are

commercially available. A battery will be unrecoverable if the active material has been

lost from the plates, or if the plates are bent due to over temperature or over charging.

Batteries which have sat unused for long periods of time can be prime candidates for

desulfation. A long period of self-discharge allows the sulfate crystals to form and

become very large. Some typical cases where lead acid batteries are not used frequently

enough are planes, boats (esp sail boats), old cars, and home power systems with battery

banks that are under utilized.

Some charging techniques can aid in prevention such as equalization charging and cycles

through discharging and charging regularly. It is recommended to follow battery

manufacturer instructions for proper charging.

SLI batteries (starting, lighting, ignition; i.e. car batteries) have less deterioration because

they are used more frequently vs deep cycle batteries. Deep cycle batteries tend to require

more desulfation, can suffer from overcharging, and can be in a very large bank which

leads to unequal charging and discharging

3.1.2.6 CURRENT RATINGS:

Lead-acid batteries are generally rated in terms of how much discharge currents

they can supply for a specified period of time; the output voltage must be maintained

above a minimum level, which is 1.5 to 1.8V per cell. A common rating is ampere-hours

(A.h.) based on a specific discharge time, which is often 8h. Typical values for

automobile batteries are 100 to 300 A.h.

As an example, a 200 A.h battery can supply a load current of 200/8 or 25A, used

on 8h discharge. The battery can supply less current for a longer time or more current for

a shorter time. Automobile batteries may be rated for cold cranking power, which is

related to the job of starting the engine. A typical rating is 450A for 30s at a temperature

of 0 degree F. Note that the ampere-hour unit specifies coulombs of charge. For instance,

200 A.h. corresponds to 200A*3600s (1h=3600s). the equals 720,000 A.S, or coulombs.

One ampere-second is equal to one coulomb. Then the charge equals 720,000 or

7.2*10^5C. To put this much charge back into the battery would require 20 hours with a

charging current of 10A.The ratings for lead-acid batteries are given for a temperatureDept. of MechanicalEngg. ,MVJCE

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range of 77 to 80F. Higher temperature increase the chemical reaction, but operation

above 110F shortens the battery life.

Low temperatures reduce the current capacity and voltage output. The ampere-

hour capacity is reduced approximately 0.75% for each decreases of 1 F below normal

temperature rating. At 0F the available output is only 60 % of the ampere-hour battery

rating. In cold weather, therefore, it is very important to have an automobile battery unto

full charge. In addition, the electrolyte freezes more easily when diluted by water in the

discharged condition.

3.1.2.7 SPECIFIC GRAVITY:

Measuring the specific gravity of the electrolyte generally checks the state of

discharge for a lead-acid cell. Specific gravity is a ratio comparing the weight of a

substance with the weight of a substance with the weight of water. For instance,

concentrated sulfuric acid is 1.835 times as heavy as water for the same volume.

Therefore, its specific gravity equals 1.835. The specific gravity of water is 1, since it is

the reference.In a fully charged automotive cell, mixture of sulfuric acid and water results

in a specific gravity of 1.280 at room temperatures of 70 to 80F. as the cell discharges,more water is formed, lowering the specific gravity. When it is down to about 1.150, the

cell is completely discharged.

Specific-gravity readings are taken with a battery hydrometer, such as one in

figure (7). Note that the calibrated float with the specific gravity marks will rest higher in

an electrolyte of higher specific gravity. The decimal point is often omitted for

convenience. For example, the value of 1.220 in figure (7) is simply read twelve

twenty. A hydrometer reading of 1260 to 1280 indicates full charge, approximately12.50 are half charge, and 1150 to 1200 indicates complete discharge.

The importance of the specific gravity can be seen from the fact that the open-circuit

voltage of the lead-acid cell is approximately equal to

V = Specific gravity + 0.84For the specific gravity of 1.280,

the voltage is 1.280 = 0.84 = 2.12V, as an example. These values are for a fully charged

battery.

3.1.2.8 CHARGING THE LEAD-ACID BATERY:

The requirements are illustrated in figure. An external D.C. voltage source

is necessary to produce current in one direction. Also, the charging voltage must be moreDept. of MechanicalEngg. ,MVJCE

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than the battery e.m.f. Approximately 2.5 per cell are enough to over the cell e.m.f. so

that the charging voltage can produce current opposite to the direction of discharge

current.Note that the reversal of current is obtained just by connecting the battery VB and

charging source VG with + to + and to-, as shown in figure. The charging current is

reversed because the battery effectively becomes a load resistance for VG when it higher

than VB. In this example, the net voltage available to produce charging currents is 15-

12=3V.A commercial charger for automobile batteries is essentially a D.C. power supply,

rectifying input from the AC power line to provide D.C. output for charging

batteries.Float charging refers to a method in which the charger and the battery are always

connected to each other for supplying current to the load. In figure the charger provides

current for the load and the current necessary to keep the battery fully charged. The

battery here is an auxiliary source for D.C. power.It may be of interest to note that an

automobile battery is in a floating-charge circuit. The battery charger is an AC generator

or alternator with rectifier diodes, driver by a belt from the engine. When you start the

car, the battery supplies the cranking power. Once the engine is running, the alternator

charges he battery. It is not necessary for the car to be moving. A voltage regulator is

used in this system to maintain the output at approximately 13 to 15 V.The constantvoltage of 24V comes from the solar panel controlled by the charge controller so for

storing this energy we need a 24V battery so two 12V battery are connected in series.It is

a good idea to do an equalizing charge when some cells show a variation of 0.05 specific

gravity from each other. This is a long steady overcharge, bringing the battery to a

gassing or bubbling state. Do not equalize sealed or gel type batteries.With proper care,

lead-acid batteries will have a long service life and work very well in almost any power

system. Unfortunately, with poor treatment lead-acid battery life will be very short.

3.1.3INVERTER

3.1.3.1 INTRODUCTION:

The process of converting D.C. into A.C. is known as INVERSION. In other

words, we may define it as the reverse process of rectification. The device, which

performs this process, is known as an INVERTOR. Inversion is, by no means, a recent

process. In olden days gas-filled tubes and vacuum tubes were used to develop inverters.

Thyratron inverter is popularly used as a large power device. Vacuum tube inverterswere generally used for high-frequency applications. Some of the main disadvantages of

the tube as well as the mercury pool type inverters are:Dept. of MechanicalEngg. ,MVJCE

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1 They are very costly

2 They are very big in size and heavy in weight

3 They have very poor efficiency

4 The voltage drop across these devices is very high

5 They are less accurate

6 They are very slow in response, etc.

The basic principle of an inverter can be explained with the help of a simple

circuit, as shown in figure. If switch S is connected alternately to position 1 and 2 at a

rapid speed and if S is not kept closed to any of the two positions (1 and 2) for too long,

and then an alternating voltage will appear across the primary winding. This can be

explained by the direction of the current flow in the primary winding.

Although the voltage applied is D.C. in nature, the direction of current flow in the

primary winding when S is connected to position 1 is from top to bottom whereas when S

is connected at position 2, the current flows from bottom to top. This change in the

direction of current flow in the primary winding gives rise to an alternating voltage in it.

The frequencies of this alternating voltage will depend on how rapidly the switch (S)positions are interchanged. This alternating voltage in the primary winding will induce an

alternating emf in the secondary winding, which will act as the A.C. output.With the

development of semi-conductor devices, a lot of improvements to took place in the design

of inverter circuits. Transistor being a fast-switching device was used as a switch for

developing low and medium power inverters

LAMP

Fig 3.2

STEAM P.M.D.C.GENERATOR BATTERY INVERTOR


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IN 4007 IN 4007 CIRCUIT DIAGRAM

9V-0-9V

CHARGER POLARITY PROTECTOR + -

100F CHARGING ON/OFF

50V INDICATOR LED SWITCH 12 V / 7.5 A.H

BATTERY

220

IN 4007

A.C MAINS 100F/50V

RF 220

CHOKE 100F/25V 0.1F 120 DISCHARGE

INDICATOR

INVERTER

BC 547 10k

TRANSFORMER 2N3055 POWER O/P 4.7F 560

100F/25V CUM OSCILATOR

40 W TUBE LIGHT


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3.1.3.2 WORKING PRINCIPLE:-

3.1.3.2.1 CHARGING CIRCUIT

The step down transformer is used to reduce the supply voltages in to 9-0-9V.

This signal is rectified by the rectifier unit with the help of diodes. The

Capacitor is used to filter the rectified signal and this signal is given to the

battery input supply.

3.1.3.2.2 INVERTING CIRCUIT:

The inverter circuit is activated when the switch is in on condition. The discharge

indication is given with the help of discharge LED. The variable resister is used to

varying the intensity of the tube light. The capacitors and transistors are used to

amplifier cum oscillator circuit. This will produce the a.c signal and this signal is

given to the inverter transformer. The inverter output is given to the load.

3.1.4 PERMANENT MAGNET D.C. GENERATOR:

3.1.4.1VoltageProduction

DC Circuits, that there are three conditions necessary to induce a voltage into

a conductor.1 A magnetic field

2 A conductor

3 Relative motion between the two.

A DC generator provides these three conditions to produce a DC voltage

output.

3.1.4.2 Theoryof Operation

A basic DC generator has four basic parts:

(1) A magnetic field;

(2) A single conductor, or loop;

(3) A commutator; and

(4) Brushes

The magnetic field may be supplied by either apermanent magnet or an

electromagnet. For now, we will use a permanent magnet to describea basic DC

generator.


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Fig 3.3

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Project Report on water turbines