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CHAPTER-1

1. INTRODUCTION

1.1 Mahi Hydel Power Station

The Mahi River is flowing in the southern part of Rajasthan near Banswara.The powerpotential of this river has been exploited by constructing#following#two#Power#Houses:-

Table No.-1

Mahi Power House-I (2x25MW) Mahi Power House -II (2 x 45MW)

FRL 281.5M(923ft.) Up Stream reservoir level 220.5M(723.5ft)

Live storage capacity 65.45TMCuft Live storage capacity 1.53Millioncubic(54.4MCft)

Mahi Hydel Power Station is R.V.U.N.Ltd. Major Hydel generating station situated on riverMahi near Banswara town, comprising of 2-phases of installed capacity 140MW.

Table No.-2

Stage Unit No. Capacity(MW)Cost(Rs.Core)

Synchronizing Date

I 1 2568

22.1.1986

2 25 6.2.1986

II 1 45

119

15.2.1989

HYDEL POWERSTATIONS:-

2 4517.9.1989

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Fig. 1.1 Mahi Hydel Power Station

1.2Mahi Hydel Power Station (140 MW):

Two power houses are operating under this power station having total installed capacityof 140 MW (2x25 & 2x45 MW). During last three years there had been appreciable decreasein the power generation from this plant due to scanty rains in the region. The details of totalenergy generated from this power station during last five years are as under:-

Table No.-3Year Energy generated(MU)

1999-00 143.12

2000-01 36.37

2001-02 68.59

2002-03 22.06

2003-04 191.63

1.3 Proposed Anas Reservoir

Anas Dam Location – 4.0 KM U/S in river Anas to PH2 near village Gararia Length – 8 KM Type – Gated spill way T.B.L. – EL. 231.50 M F.R.L. – EL 228.50 M M.D.D.L. – EL 216.6 M Catchment Area – 1840 Sq. Miles Live Storage – 40 TMC Dead Storage – 9 TMC

Hydel Channel Length – 9 KM

Discharge – 31.15 CUMECS

Bed width – 7.0 M

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Side slope – 1:1 Bed slope – 1 in 6000 F.S.D. – 3.06 M

1.4 PLANT SPECIFICATION’S:- (2 X 45 MW)

• Capacity of machines : 2 x 45 MW.

• Type of turbine : FRANCIS[VERTICAL SHAFFT]

• Date of commissioning of Unit I : 22-1-1986.

• Date of commissioning of Unit II : 06-2-1986.

• Date of dedication of Nation : 13-2-1986.

• Type of generator : UMBRELLA Type.

• Capacity of generator : 27.778 MVA.

At 11 kV, 0.9pf, lag.

• Rated Speed : 250 rpm

• Capacity of power transformer : 11/132 kV,

31.5 MVA, 3-Ø.

1.5 ELEMENTARY DESCRIPTION OF “MAHI HYDRO POWERSTATION”Definition:

A generating station which utilizes the potential energy of water at a high level for thegeneration of electrical energy is known as a hydroelectric power station.It contains the following of the elements:-

1. Dam:A dam is barrier which stores water and creates water head. Dams are built of

concrete or stone masonry, earth or rock hill. The type of arrangement depends uponthe topography of the sight.2. Penstock:

Penstock is open or closed conduits which carry water to the turbines. They aregenerally made of reinforced concrete or steel. Concrete penstock is suitable for low ormedium as greater pressure causes rapid deterioration of concrete. Number – 2 nos. Length

o Unit 1 – 360.7 Mo Unit 2 – 361.2 M

Diameter – 5 M Designed Discharge – 64.2 CUMECS

Tunnel – 108 M EL at Intake – EL. 20 M

o EL at Power House – EL. 130 M

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Steel Plates – 16 MM to 25 MM

3. Reservoir:It is constructed behind the dam to store water. From here the water takes to

turbine through the penstock. The generation depends upon the head of the water behinddam. Generally the required head is about 281m

4. Water turbines:Water turbines are used to convert the energy of falling water into electrical

energy. Here the water turbine used is FRANCIS type turbine; it is a reaction turbinein which water enters the runner partly with pressure energy and partly with velocityhead.

5. Generating Units:An alternator is connected with the shaft of turbine. The alternator used is of 3-

phase silent pole type, it is used for low speed. When shaft of water turbine starts torotate the generator also rotate and electricity is produced.

1.6 HYDROPOWER GENERATING STATIONS:-

Hydropower generating stations convert the energy of moving water into electricalenergy by means of a hydraulic turbine coupled to a synchronous generator. The power thatcan be extracted from a waterfall depends upon its height and rate of flow. Therefore, the sizeand physical location of a hydropower station depends on these two factors.

The available hydropower can be calculated by the following equation:

Where,

P = Available water power (kW)

q = Water rate of flow (m3/s)

h = Head of water (m)

9.8 = Coefficient used to take care of units.

The mechanical power output of the turbine is actually less than the value calculated bythe preceding equation. This is due to friction losses in the water conduits, turbine casing, andthe turbine itself. However, the efficiency of large hydraulic turbines is between 90 and 94percent. The generator efficiency is even higher, ranging from 97 to 99 percent, depending onthe size of the generator.

Hydropower stations can be divided into three groups based on the head of water:

1. High-head development

2. Medium-head development

3. Low-head development

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Fig.: 1.2 One-line diagram of electric-power system

High-head developments have heads in excess of 300 m, and high-speed turbines areused. Such generating stations can be found in mountainous regions, and the amount ofimpounded water is usually small. Medium-head developments have heads between 30 m and300 m, and medium speed turbines are used. The generating station is typically fed by a largereservoir of water retained by dikes and a dam. A large amount of water is usually.

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CHAPTER-2

2. ELECTRICITYElectrical#equipment#is dangerous if handled incorrectly; therefore, we

must observe all applicable safety pre-cautions when working with or around electricalequipment. We will discuss basic concepts of electricity, electrical terms, electrical equipment,and applicable safety precautions.

2.1 How is electricity made?

There are actually several ways of making electricity. Each technique involves the useof a turbine to roll and renovate kinetic energy into electricity. Electricity is made when aturbine moves a huge magnet around an extremely large wire. This movement provides to thrillthe wire. Electricity is then further pushed away from this generator by way of individualtransformers. Steam, combustion gases, and other water are usually used to turn turbines forthe generating electricity. Wind might as well be used. When steam is used, vestige fuels, suchas lubricate, gas, or coal, are frequently burned for the reason of generating steam from water.The steam is then used to rotate the turbine and make electricity.

At times nuclear energy is also made use to generate steam to turn turbines. Whennuclear power is made used, uranium is rip apart, making heat energy. The heat energy isfunctional to water, making steam for use in turning a turbine. Combustion gases might as wellbe made use to make electricity. In usual such cases, a gas turbine are engaged in burningnatural gas or may be with low-sulfur oil. The fuel is mixed with condensed air and burned incombustion chambers. In these chambers, high-pressure combustion gases shape up and arethen functional to the turbine, causing it to turn.

Sometimes water is made use when one wants to create electricity. In such a case, wateris made to drop on the blades of a turbine, rotating it. This needs an extremely large amount ofwater, which is generally obtained from a pool or a lake. The body of water should be situatedhigher than the turbine in order to turn its massive blades.

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CHAPTER-3

3. How Hydropower Plants Work

Worldwide, hydropower plants produce about 24 percent of the world's electricity and supplymore than 1 billion people with power. The world's hydropower plants output a combined totalof 675,000 megawatts, the energy equivalent of 3.6 billion barrels of oil, according to the NationalRenewable Energy Laboratory. There are more than 2,000 hydropower plants operating in theUnited States, making hydropower the country's largest renewable energy source.In this edition of HowStuffWorks, we'll take a look at how falling water creates energy and learnabout the hydrologic cycle that creates the water flow essential for hydropower. You will alsoget a glimpse at one unique application of hydropower that may affect your daily life.

3.1 The Power of Water

When watching a river roll by, it's hard to imagine the force it's carrying. If you have ever beenwhite-water rafting, then you've felt a small part of the river's power. White-water rapids arecreated as a river, carrying a large amount of water downhill, bottlenecks through a narrowpassageway. As the river is forced through this opening, its flow quickens. Floods are anotherexample of how much force a tremendous volume of water can have.

Hydropower plants harness water's energy and use simple mechanics to convert that energy intoelectricity. Hydropower plants are actually based on a rather simple concept -- water flowingthrough a dam turns a turbine, which turns a generator. :

Fig. 1.3 Most hydropower plants

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Dam –

Most hydropower plants rely on a dam that holds back water, creating a large reservoir. Often,this reservoir is used as a recreational lake, such as Lake Roosevelt at the Grand Coulee Dam inWashington State.

Intake –

Gates on the dam open and gravity pulls the water through the penstock, a pipeline that leads tothe turbine. Water builds up pressure as it flows through this pipe.

Turbine –

The water strikes and turns the large blades of a turbine, which is attached to a generator aboveit by way of a shaft. The most common type of turbine for hydropower plants is the FrancisTurbine, which looks like a big disc with curved blades. A turbine can weigh as much as 172

tons and turn at a rate of 90 revolutions per minute (rpm), according to the Foundation for Water& Energy Education (FWEE).

Generators –

As the turbine blades turn, so do a series of magnets inside the generator. Giant magnets rotatepast copper coils, producing alternating current (AC) by moving electrons. (You'll learn moreabout how the generator works later.)

Transformer –

The transformer inside the powerhouse takes the AC and converts it to higher-voltage current.

Power lines –

Out of every power plant come four wires: the three phases of power being producedsimultaneously plus a neutral or ground common to all three. (Read How Power Distribution GridsWork to learn more about power line transmission.)

Outflow –

Used water is carried through pipelines, called tailraces, and re-enters the river downstream. Thewater in the reservoir is considered stored energy. When the gates open, the water flowingthrough the penstock becomes kinetic energy because it's in motion. The amount of electricitythat is generated is determined by several factors. Two of those factors are the volume of waterflow and the amount of hydraulic head. The head refers to the distance between the water surfaceand the turbines. As the head and flow increase, so does the electricity generated. The head isusually dependent upon the amount of water in the reservoir.

Pumped StorageThe majority of hydropower plants work in the manner described above. However, there's

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another type of hydropower plant, called the pumped-storage plant. In a conventionalhydropower plant, the water from the reservoir flows through the plant, exits and is carrieddown stream. A pumped-storage plant has two reservoirs:Upper reservoir –

Like a conventional hydropower plant, a dam creates a reservoir. The water in this reservoirflows through the hydropower plant to create electricity.

Lower reservoir - Water exiting the hydropower plant flows into a lower reservoir rather

than re-entering the river and flowing downstream.

Using a reversible turbine, the plant can pump water back to the upper reservoir. This is done inoff-peak hours. Essentially, the second reservoir refills the upper reservoir. By pumping waterback to the upper reservoir, the plant has more water to generate electricity during periods ofpeak consumption.

3.2 Inside the Generator

The heart of the hydroelectric power plant is the generator. Most hydropower plants have severalof these generators.

Fig-1.4 The generators

The generator, as you might have guessed, generates the electricity. The basic process ofgenerating electricity in this manner is to rotate a series of magnets inside coils of wire.

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=This process moves electrons, which produces electrical current.TheHoover Dam has a total of 17 generators, each of which can generate up to 133 megawatts.The total capacity of the Hoover Dam hydropower plant is 2,074 megawatts. Each generator ismade of certain basic parts:

Shaft

Excitor

Rotor

Stator

As the turbine turns, the excitor sends an electrical current to the rotor. The rotor is a series oflarge electromegnets that spins inside a tightly-wound coil of copper wire, called the stator. Themagnetic field between the coil and the magnets creates an electric current.

In the Hoover Dam, a current of 16,500 volts moves from the generator to the transformer, wherethe current ramps up to 230,000 volts before being transmitted.

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CHAPTER-4

4. POWER TRANSFORMER

4.1 TRASNFORMER CONSTRUCTION:

There are two basic types of core assembly, core form and shell form. In the core form,the windings are wrapped around the core, and the only return path for the flux is through thecenter of the core. Since the core is located entirely inside the windings, it adds a little to thestructural integrity of the transformer’s frame. Core construction is desirable whencompactness is a major requirement. Figure Z-6 illustrates a number of core type configurationsfor both single and multi-phase transformers.

Fig 1.5 -power transformer

This manu-aclontaions a generalized overview of the fundamentals of transformertheory and operation. The transformer is one of the most reliable pieces of electrical distributionequipment. It has no moving parts, requires minimal maintenance, and is capable ofwithstanding overloads, surges, faults, and physical abuse that may damage or destroy otheritems in the circuit. Often, the electrical event that burns up a motor, opens a circuit breaker,or blows a fuse has a subtle effect on the transformer. Although the transformer may continueto operate as before, repeat occurrences of such damaging electrical events, or lack of evenminimal maintenance can greatly accelerate the evenhml failure of the transformer.

The fact that a transformer continues to operate satisfactorily in spite of neglect andabuse is a testament to its durability. However, this durability is no excuse for not providingthe proper care. Most of the effects of aging, faults, or abuse can be detected and corrected bya comprehensive maintenance#and#testing#program.

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4.2 COSERVATOR TANK:

[A]. Conservator or expansion type tanks use a separate tank to minimize the contactbetween the transformer oil and the outside air (see figure). This conservator tank is usuallybetween 3 and 10 percent of the main tank’s size. The main tank is completely filed with oil,and a small conservator tank is mounted above the main tank level. A sump system is used toconnect the two tanks, and only the conservator tank is allowed to be in contact with the outsideof transformer oil flow.

Fig. 1.6 COSERVATOR TANK

[B]. although this design minimizes contact with the oil in the main tank, the auxiliarytank’s oil is subjected to a higher degree of contamination because it is making up for theexpansion and contraction of the main tank. Dangerous gases can form in the head space of theauxiliary tank, and extreme caution should be exercised when working around this type oftransformer. The auxiliary tank’s oil must be changed periodically, along with a periodicdraining of the sump.

4.3 BUSHINGS:

The leads from the primary and secondary windings most be safely brought through thetank to form a terminal connection point for the lie and load connections. The bushing insulatoris constructed to minimize the stresses at these points, and to provide a convenient connectionpoint

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The bushing is designed to insulate a conductor from a barrier, such as a transformer lid, andto safely conduct current from one side of the barrier to the other. Not only must the bushinginsulate the live lead from the tank surfaces, but it must also preserve the integrity of the tank’sseal and not allow any water, air, or other outside contaminants to enter the tank.

Fig.1.7 - bushing

[A]. here are several types of bushing construction; they are usually distinguished by their

voltage ratings, although the classifications do overlap:

1. Solid (high alumina) ceramic-(up to w5kv).

2. Porcelain-oil filled (25 to 69Kv).

3. Porcelain-compound (epoxy) filled (25 to 69kV).

4. Porcelain--synthetic resin bonded paper-filled (34.5 to 115kV).

5. Porcelain-oil-impregnated paper-filled (above 69kV, but especially above 275kv).

[B]. For outdoor applications, the distance over the outside surface of the bushing is

increased by adding “petticoats” or “watersheds” to increase the creep age distance between

the line terminal and the tank. Contaminants will collect on the surfaces of the bushing and

form a conductive path. When this creep age distance is bridged by contaminants, the voltage

will flashover between the tank and the conductor. This is the reason why bushings must be

kept clean and free of contaminants.

[C]. Transformer bushings have traditionally been externally clad in porcelain because

of its excellent electrical and mechanical qualities. Porcelain insulators are generally oil-filled

beyond 35 kV to take advantage of the oil’s high dielectric strength. There are a number of

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newer materials being used for bushings, including: fiberglass, epoxy, synthetic rubbers,

Teflon, and silica compounds. These materials have been in use for a relatively short tile, and

the manufacturer’s instructional literature should be consulted when working with these

bushings.

[D].Maintenance. Bushings require little maintenance other than an occasional

cleaning and checking the connections. Bushings should be inspected for cracks and chips, and

if found, should be touched-up with Glyptic paint or a similar type compound. Because,

bushings are often called on to support a potion of the line cable’s weight, it is important to

verify that any cracks have not influenced the mechanical strength of the bushing assembly.

[E]. Testing. Most bushings are provided with a voltage tap to allow for power factor

testing of the insulator. If they have no tap, then the power factor test must be performed using

the “hot collar” attachment of the test set. The insulation resistance-dielectric absorption test

can also be performed between the conductor and the ground connection.

4.4 LIGHTNING ARRESTERS:

Most transformer installations are subject to surge voltages originating from lightningdisturbances, switching operations, or circuit faults. Some of these transient conditions maycreate abnormally high voltages from turn to turn, winding to winding, and from winding toground. The lightning arrester is designed and positioned so as to intercept and reduce the surge

voltage#before#it#reaches#the#electrical#system.

[A]. Construction. Lightning arresters are similar to big voltage bushings in bothappearance and construction. They use a porcelain exterior shell to provide insulation andmechanical strength, and they use a dielectric filler material (oil, epoxy, or other materials) toincrease the dielectric strength (see Figure). Lightning arresters, however, are called on toinsulate normal operating voltages, and to conduct high level surges to ground. In its simplestform, a lightning arrester is nothing more than a controlled gap across which normal operatingvoltages cannot jump. When the voltages exceeds a predetermined level, it will be directed toground, away from the various components (including the transformer) of the circuit. There aremany variations to this construction. Some arresters use a series of capacitances to achieve acontrolled resistance value, while other types use a dielectric element to act as a valve materialthat will throttle the surge current and divert it to ground.

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[B]. Mechanism. Lightning arresters use petticoats to increase the creep age distancesacross the outer sm. face to ground. Lightning arresters should be kept clean to prevent surfacecontaminants from forming a flashover path. Lightning arresters have a metallic connection ontop and bottom. The connectors should be kept free of corrosion.

Fig-1.8 lightining arrestor

[C]. Testing. Lightning arresters are sometimes constructed by stacking a series of thecapacitive/dielectric elements to achieve the desired voltage rating. Power factor testing isusually conducted across each of the individual elements, and, much like the power factor teston the transformer’s windings, a ratio is computed between the real and apparent current valuesto determine the power factor. A standard insulation resistance- dielectric absorption test canalso be performed on the lightning arrester between the line connection and ground.

4.5CURRENT TRANSFORMER:

(A) CONNECTION’s

(B) TOP VIEW OF C.T.

(C) POSITION ON TRANSFORMER (Location)

(D) C.T. OPEN FOR MENTINANCE

The primary winding of a current transformer

A current transformer is specified as being 600 A, 5 A class C200. Determine itscharacteristics. This designation is based on ANSI Std. C57.13–1978. 600 A is the continuousprimary current rating, 5 A is the continuous secondary current rating, and the turns ratio is600/5=120. C is the accuracy class, as defined in the standard. The number following the C,which in this case is 200, is the voltage that the CT will deliver to the rated burden impedanceat 20 times rated current without exceeding 10 percent error. Therefore, the rated burdenimpedance is This CT is able to deliver up to 100 A secondary current to load burdens of up to

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20 with less than 10 percent error. Note that the primary source of error is the saturation of theCT iron core and that 200 V will be approximately the knee voltage on the CT saturation curve.This implies that higher burden impedances can be driven by CT’s which will not experiencefault duties of 20 times rated current, for example.

A typical wave CT connection is shown in Fig. The neutral points of the CT’s are tiedtogether, forming a residual point. Four wires, the three-phase leads and the residual, are takento the relay and instrument location. The three-phase currents are fed to protective relays ormeters, which are connected in series. After these, the phases are connected to form and tiedback to the residual.

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CHAPTER-5

5. GENERATORS

5.1 AC GENERATORS:-

AC generators are also called alternators. In an ac generator, the field rotates, and thearmature is stationary. To avoid confusion, the rotating members of dc generators are calledarmatures; in ac generators, they are called rotors. The general construction of ac generators issomewhat simpler than that of dc generators. An ac generator, like a dc generator, has magneticfields and an armature. In a small ac generator the armature revolves, the field is stationary, andno commentator is required. In a large ac generator, the field revolves and the armature iswound on the stationary member or stator. The principal advantages of the revolving-fieldgenerators over the revolving-armature generators are two essential parts of a dc generator: areas follows: The yoke and field windings, which are the load current from the stator is stationary,and connected directly to the external circuit the armature, which rotates withoutusing a commentator.

5.2 GENERATOR:-

Technical parameters of generator

Type of product – 5 V 596/152-24 Speed – 250 rpm Runaway speed – 475 rpm Power factor – 0.9 lag Rated voltage – 11 KV Rated output – 45 MW Rated Output at Rated Voltage Zero Leading p.f. (Sync. Con. Operation) – 32

MVAR Rated frequency – 50 Hz Flying wheel effect of the rotating parts GD2 – Tonne M2 2100 Armature winding resistance per phase at 75 oC – 0.0086 Ω Resistance of winding per phase at 15 oC – 0.00693 Ω Resistance of field winding at 75 oC – 0.164 Ω Resistance of rotor field winding at 15 oC – 0.121 Ω

5.3 STATOR:

The stator core and winding are housed in a fabricated steel frame made in four sections.The stator core is built of vanished segmental silicon steel laminations held in the frame bydovetailed key bars, welded to the frame. The core is divided into the packets by narrow radialsteel spears, thus forming ventilating ducts leading from the stator core to the outside periphery.The core is clamped between the bottom frame plate and segmental flanges on the top by meansof through bolts.

Stator Core inside diameter – 5250 mm Stator Core outside diameter – 5960 mm Gross Length of core – 1520 mm Net Length of core – 1162 mm

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Total weight of Iron – 50,000 Kgs Total no. of slots – 306

Calculated Capacitance of Stator Winding per phase – 0.36 MFThe stator winding is of the double layer three turned diamond pulled coil type,

assembled in open slots. Each coil is made of a number of insulated copper strands, with asemi-rebel transposition in the end of Epoxy Movolac glass Mica paper tapes and flexible Micaflakes taps in the end winding. All the coils are identical and interchangeable. Temperaturesensors of resistance type are inserted between coil sides in all three phases to provide acontinuous indication of coil temperature.

5.4 ROTOR:

The rotor is of the friction held type and is built up of thin sheet steel laminations rigidlyclamped between steel and plates by a large number of through bolts. The clamping force inthe rim is such that the fractional forces between the laminations prevent them from slippingrelative to one another at any speed up to and including runway.The spider which supports the rim is of fabricated steel construction with dished arms from acentral hub. The lower plane is machined to fit on top of the generator shaft. The driving torqueis transmitted from the shaft to the spider by radial keys. This method of construction permitsthe lifting of rotor independent of the shaft. The weight of the rim and poles is supported onthe heavy steel bars welded on the outer end of the spider arms.

No. of poles – 24 Weight of Copper in field winding in pole – 360 Kgs Width and Height of the pole body – 345 Х 212 mm Total weight of rotor – 15,5,000 Kgs No. of brushes per collector ring – 16 Types of Collector Ring Brush - Electro Graphite Carlooun Brush

The field poles are built up of sheet steel punching clamped between steel and platesand secured to the rim by two T-head projections on each punching and end plate. Theseprojections engage with corresponding slots in the rotor rim. Two pairs of tapered keys drivenalong the slots pull the poles down on the rim.Each pole carries a field coil made from straight lengths of copper straps, dovetailed and brazedat the ends. At intervals down each coil, the copper is increased in width to from fins forimproved cooling. The inter turn insulation is of epoxy resign bonded asbestos paper and theinsulation between the coil and pole body is epoxy glass fabric bored.In addition, each pole is equipped with six damper bars of circular cross section made of highconductivity copper embedded in semi-closed slots in the pole face, which are brazed at eachend into copper punching clamped between pole and end plates. Axial flow aero-fill type fansare mounted at each end of the rotor. A polished steel segmental brake track is bolted to thebottom of the spider hub.5.5 AIR COOLER:

Each of the twin shades of air coolers consists of a nest of admiralty Brass cubes woundwith copper wire covered in a mild steel frame. The tube ends are roller expanded into Brassplates on which are mounted the inlet and return end water boxes fabricated from mild steel.The thickness of water box includes generous corrosion allowance and these are internallysubdivided to provide for multiple water passes for requisite flow pattern. The inlet water boxis filled with vent valve and with drain valve. The differential thermal expansion between tubes

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and frame is absorbed by the action of neoprene packing between the frame and the tube plate.The coolers are provided with support foot plates at the bottom for baling down to the concretefoundations. A drip tray is provided below the cooler for collecting any condensate.

5.6 OIL COOLERS:Each of the four plug-in-type oil coolers consists of a bank of 'U' shapes admiralty Brass

tube with Copper wire carried in a Steel frame with inlet end terminating in a rolled Brass tubeplate and the other 'U' end supported in a tube support fixed frame. The tube rollers expandedinto the tube plate. The water box which is of mild steel fabrication is belted to the tube plateand amply proportional to reduce turbulence and pressure drop. The differential thermalexpansion between tube and frame is absorbed by the 'U' shaped tubes.

5.7 GENERATOR TYPES AND DRIVES:-

A large amount of electricity is required to power machinery that supplies to Drives.

Fig.1.9 -generator

5.8 PERMANENT MAGNET GENERATOR (P M G):

The PMG provides a 3-Ø low voltage supply to the turbine governed at a frequency directlyrelated to the speed of the set. Provision has been made for synchronizing its voltage to that ofmain generator during its excitation, if required for turbine governor operation.

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5.9 PERMANENT MAGNET GENERATOR

Type – PMG 104/0.24 Capacity – 250 VA Voltage – 110 V Current – 1.3 Amp Speed – 250 rpm Frequency – 50 Hz

5.10 COLLECTOR RINGS AND BRUSH GEARS:The collector rings are attached to and are insulated from the fabricated steel shaft

mounted on the spider. The leads from the collector to the field run along the shaft and joinedat suitable points to facilitate dismantling of the rotor.A DC generator is a rotating machine that changes mechanical energy to electrical energy.The power output depends on the size and design of the dc generator. A typicaldc generator is shown in figure.

Fig.-1.10 D.C Excitor

5.11 D.C. EXCITOR: -

» Rated output 255 kW.

» Rated voltage 178 V.

» Ceiling voltage 279 V-max.

» Rated speed 250 rpm.

» Exciter response ratio 1.5 p.v.

» No. of poles 8

» Max. Temperature rise at rated output at armature winding, armature core fieldwinding

And Core, =70°c.

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» Armature circuit resistance= 0.0179 at 75°c

» No. of Brushes -8*5=40

» Exciter field current at rated output= 40.8amp. (MCR=55.7 amp.).

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CHAPTER-6

6. CONCLUSION

A student gets theoretical knowledge from classroom and gets practical knowledge

from industrial training. When these two aspects of theoretical knowledge and practical

experience together then a student is full equipped to secure his best.

In conducting the project study in an industry, students get exposed and have knowledge of

real situation in the work field and gains experience from them. The object of the summer

training cum project is to provide an opportunity to experience the practical aspect of

Technology in any organization. It provides a chance to get the feel of the organization and its

function.

I have privilege taking my practical training at " MAHI HYDRO POWER HOUSE - I

" where power generation takes place in bulk. The fact that Hydro energy is the major source

of power generation itself shows the importance of Hydro power generation in India

In Hydro power plants, the potential energy of water is utilized by the turbine to rotate

coil at high torque. The torque so produced is used in driving the coil coupled to generators

and thus in generating ELECTRICAL ENERGY.