TG Project Report

8/20/2019 TG Project Report

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PROFILE OF BHEL

Bharat Heavy Electrical Limited is the largest Engineering and Manufacturing Enterpriseof its kind in the Public Sector in India. It ranks among the top telve organi!ations inthe orld" engaged in the manufacture of poer generation e#uipment. $he company provides products" systems and services in the fields of Energy" industry and

transportation.BHEL has %& manufacturing plants and & poer repair divisions. ' vital link to this chainof BHEL manufacturing units is the unit at (amachandrapuram" Hyderabad.BHEL" Hyderabad manufactures turbogenerators of rating up to )** M+ for industrialapplications and for poer generation to $hermal poer stations.

$hese turbogenerators are supplied together ith the turbines and matchinge,citation systems" and are used mostly in the Paper" Sugar" -ement" Petrochemical"ertili!ers" (ayon industries etc. and thermal poer stations. $he turbogenerators are based on proven designs and kno/ho backed by from over three decades of e,periencegained by BHEL engineers in this field. 0eeping pace ith the latest development ininsulation systems to optimi!e the design" BHEL" Hyderabad has installed the micalastic12PI3 system of insulation.

BHEL have pleasure in introducing the design features" manufacturing process"testing facilities and modern methods adopted in the manufacture of turbogenerators toensure #uality and reliability. It is the only one in 'SI' that has the latest type of insulation system called the 2'--4M P(ESS4(E IMP(E56'$I76.

$he products manufactured in BHEL comprise of8• $urbines %3Steam $urbines )3 5as $urbines

• $urbine 5enerators %3 Steam $urbine 5enerators)3 5as $urbine 5enerators93 'ir -ooled 5enerators

• Sitchgears17-BS:S;3• -ompressors• Heat E,changers• Boiler eed Pumps• Pulverisers1Ball:Bol mill3• 7il/field e#uipments1on shore oil rigs3• -ircuit Breakers• Synchronous -ondensers• Motors• E,citers


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$he range of turbo generators manufactured at BHEL" Hyderabad is from %.<M+ to )**M+. $he machine of largest capacity manufactured is %%* M+ 'ir cooledturbogenerator.

SPECIAL FEATURES OF TURBOGENERATORS DESIGNED BY BHEL

• High output to eight to eight ratio.• $hermo/setting class/f epo,y insulation. Both resin rich and micalastic vacuum

impregnation system.• Lo loss high grade silicon steel for laminations.• 7ptimally designed fans on rotor.• Better voltage ave from ith less harmonic content.• Lo indage loss and lo noise.• Static=brushless e,citation.• split casing design for a loer manufacturing cycle for a loer manufacturing

cycle for 2PI design

INTRODUCTIONElectrical machines are broadly classified into'- Machines>- Machines

'- Machines can be categori!ed as(otating MachinesStatic Machines

$hey can be further classified asSingle Phase '- Machines$hree Phase '- Machines8 %.5enerator ). Motor '- generators can be broadly classified into to types. $hey are%. S?6-H(7674S 5E6E('$7(8$hese are the machines in hich the speed of the rotor and flu, are in synchronism. E@8$urbo 5enerator

). 'S?-H(7674S 5E6E('$7(8$hese are the machines in hich the flu, speed and rotor speed ill not be same .E@8Induction motors.

Inherently all the machines are '- Machines. '- or >- depends on the flo of currentin the e,ternal circuit. Electric energy is mainly used for the ease ith hich it can bedistributed and converted to other desired forms mechanical energy" being the chiefsource for Electrical energy is converted to the latter by using the mechanical force tomove a current/ carrying conductor in the magnetic field.


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$he 9/phase Synchronous 5enerators are the idely used machines for poer productionon large scale bases. Hence" the dominant component of poer generation is turbogenerator. $he ord Aturbo stands for Aturbine driven. $urbo generators aresynchronous machines" hich are usually run by steam turbines or gas turbines.

' 9/Phase synchronous generator basically consists of to parts%. Stator CStationary part of the generator" used as the armature.). (otor C(otating part of the generator" used to generate the alternating flu,.Synchronous generators can be classified into various types based on the medium usedfor generation" they are8%. $urbo/5enerators Steam 1or3 5as). Hydro 5enerators9. Engine >riven 5enerators

PRINCIPLE GOVERNING THE OPERATION OF A

TURBO GENERATOR

'n electrical machine is an electromechanical device" hich converts mechanical energyto electrical energy armor vise versa. 'n electrical generator is machineD it convertsmechanical energy into electrical energy. 'n electrical motor is machine" hich convertselectrical energy into mechanical energy.

$he energy conversion is based on the principle of production of dynamicallyinduced e.m.f. 'ccording to the Aaradays las of electromagnetic induction" henever a current carrying conductor cuts magnetic flu, " dynamically induced emf is produced init .$hat is " henever the relative motion beteen a conductor and a magnet. $hat is hena moving coil cuts the magnetic lines or moving magnet field passes through a stationary

coil or a conductor" then an e.m.f induced in the conductor. $he induced e.m.f. is directly proportional to the rate of change of flu, and the no of turns. It is given by E /6 dφ= dt

$o produce relative motion" either the armature or the magnet has to rotate. In a>- generator the armature is the rotating part and in an '- generator" it is magnet.

$he basic purpose of EM 5enerator is the conversion of mechanical to electricalenergy .$he energy conversion is based on the principle of production of >ynamicallyinduced EM.

Hence basic essential parts re#uired in the production of Production of Poer bythe Electrical 5enerator are

• ' magnetic field

• ' -onductor = -oil• (elative motion = mechanical force

In turbo Generator, the magnetic field is rotating part : the coil is stationary.


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INTRODUCTION TO TURBO GENERATORS

$he generators are primary source of all electrical energy. $hese Machines are the largestenergy converters found in the orld. >epending on the current output i.e >- or '-" the

generators are classified as follos8• '- 5enerators or 'lternators or $urbo generators• >- 5enerators

$he important difference beteen the above to 5enerators is that in a >.-. 5enerator armature inding is placed on the rotor in order to provide a ay of convertingalternating voltage generated in the inding to a direct voltage at the terminals throughthe use of a rotating commutator. Since no commutator is re#uired in an '- 5enerator isusually more convenient and advantageous to place the field inding on the rotating part. 'n alternator is an electrical machine" hich converts mechanical into electricalenergyD the electrical energy is in the form of alternating current and voltage. It operateson the principle of electro magnetic induction. High/speed alternators driven by steam

turbines are called $urbo generators. 5enerally the turbines used to drive these turbo generators are of reaction type.$urbo generators are synchronous machines" hich are usually run by steam turbines orgas turbines. Steam turbine and gas turbine driven generators differ in construction bylocation of output terminals on stator frame or type of cooling etc." the basic design ofthe generator being the same. or steam turbine generators" the output terminals arelocated at bottom of stator frame and for gas turbine generators they are on the top. 5asturbine generators mostly employ open air cooling and steam turbine generators mostlyemploy closed air circuit ater cooling. The lare !a"a!#t$ turbo enerator% are&o%tl$ bet'een ( )*+ to -..+. ($he main principle on hich a generator orksis aradayFs La of Electro Magnetic Induction.

' synchronous generator is a rotating electromagnetic device that convertsmechanical energy into electrical energy by taking the mechanical input from a primemover 15as turbine or Steam turbine3 and magnetic energy from e,citation. $he standard construction consists of armature inding mounted on astationary element called stator and field indings on a rotating element called rotor.$hese synchronous machines" ith a smooth cylindrical type rotor are used for steamturbine driven alternators i.e." turbo/generator that run at very high speeds. $he stator supports the armature core" having slots on its inner periphery for housing the armature conductors .$he magnetic poles are e,cited or magneti!ed fromdirect current supplied by a d.c. source .Brush/less e,citation system can be used inhich a 9/phase a.c. e,citer and a group of rectifiers supply d.c. to the alternator .

Hence" brushes" slip rings and commutator are eliminated. $he rotor is like a flyheelhaving alternate 6 and S poles fi,ed to its outer rim. $he Speed of all Synchronous machines is intimately connected ith thefre#uency. $he highest possible speed for


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$he synchronous generator is universally employed for the generation of 9/phase poer at all generating stations. It is a doubly e,cited '- machine" as its field indingimports >- poer and its armature inding e,ports '- poer.$he generation of dynamically induced e.m.f. is based on aradays las of Electromagnetic induction" hich says that the relative motion beteen the field flu,and the armature inding. In synchronous generator" to attain the relative motion" thearmature is stationary hile the field poles are rotating. T$"e% o2 %$n!hronou% enerator%

• Salient pole generators• -ylindrical or 6on/salient generators

Sal#ent "ole enerator%8 $he salient pole generators have the poles proecting out onthe rotor and it uses concentrated inding. $he air gap beteen the rotor and stator isnon/uniform.C$l#n/r#!al or Non0%al#ent "ole enerator%8 $he cylindrical generators have the fieldinding as a distributed inding housed in rotor slots. $he air gap beteen the rotor and stator is uniform.

GENERAL ASPECTS OF TURBOGENERATOR

$urbo generators are classified according to their function and the conditions under hich they are supposed to ork and deliver the output.

CLASSIFICATION OF SYNCHROUS GENERATORS

Synchronous generators are classified into to main categories based on their designas8

• Smooth cylindrical rotor machines• Salient pole machines.

5enerators driven by steam or gas turbines have cylindrical= round rotors ith slotsinto hich distributed field indings are placed. $hese round rotor generators areusually referred to as turbo generators and they usually have ) or & poles. 5eneratorsdriven by hydraulic turbines have laminated salient pole rotors ith concentrated fieldinding and a large number of poles.CLASSIFICATION BASED ON DRIVE 3GAS TURBINE GENERATORS3 5as turbine can be installed outdoors and ithout proper civil structure. $hey have to operate under e,treme temperature conditions. Hence"generators driven by 5as turbines are usually installed ith a minimum civil foundationon a base frame. 'n enclosure is provided to protect from the elements. $hey can be opencircuit air cooled or closed circuit air/ater cooled. $he terminals are usually at the top of

the generator on the e,citer side for onard connection to bus/ducts or through a 5'-.STEA+ TURBINE GENERATORS3 Small rating steam turbines are designed for highspeeds can hence generators are driven by steam turbines through speed reductiongearbo,es. But at higher capacities" the losses in the gearbo, offset any advantageobtained by high/speed design for steam turbines. Hence large capacity steam turbinesare designed for 9*** (PM and connected to generators directly. Steam turbines areerected on an elaborate civil foundation in proper poer house at an elevation of ; to Jmeters. $he space belo the turbine is employed for locating the condenser. Hence" as


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the generator also is located at this height" the space belo the generator is utili!ed for locating the air coolers. $he terminals are taken out from the bottom of the machine onthe e,citer side for onard connection to bus/ducts.

CLASSIFICATION BASED ON SPEED3

$he construction of the generator as ell as the material used is dependent onthe speed at hich the machine is designed to operate. High/speed machines 19***=9;***rpm3 are of )Cpole design. $hey employ solid cylindrical rotors made of high #ualitysteel forging. Slots are milled into the rotor to accommodate the rotor inding. $oretaining rings or end/bells made of high strength austenitic steel forging hold the rotor inding in place. $o a,ial fans" one on each side for circulating cooling air in themachine. 5enerators ith &Cpoles run at %


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located belo" on the side or on the top of machine. 5as turbine generators are mountedon base/frames. 'nd hence the coolers are mounted on the side.

5enerators up to %)< M+ capacity of air/cooled. or larger rating machines" hydrogencooling is employed. Even larger machines 1K


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CO+PARISON BETEEN - POLE AND : POLE TURBOGENERATORS

Sno - POLE 85... RP+9 : POLE 8(*.. RP+9

CONSTRUCTION OF ROTOR

1. Solid rotor construction Laminated rotor construction

2. Ventilation slots Ventilation ducts between the laminationpackets

3. Axial entry of air and radial outlet Axial entry of air and radial outlet

4. Smaller diameter Larger diameter compared to 2 pole. !edges are pro"ided and shorted by

retaining rings#opper damper bars are pro"ided shorted bycopper wire for rotors with dia$%&&&mm andshorted by bron'e ring for rotors with dia(%&&&mm

). *etaining ring is compulsory *etaining ring is not compulsory upto %&&&mmdia.

+. Large Axial fan Small *adial fan

CONSTRUCTION OF STATOR

,. Stator with *oebel bar winding.-ndi"idual stator bars made separately

Stator with multi turn winding. ulled stator coils.

/. 0o restriction on si'e of stator bars 1axi puller machine setting imposes l imit onstator bar si'e

%&. Stator si'e limited by impregnation tankdimensions

0o such limit due to small ratings

PERFORMANCE

%%. 0oise le"el without enclosure %&&dA 0oise is less compared to 2 polemcs5,dA6

%2. 7igher efficiency Lower efficiency5due to higher mechanicallosses 8 rotor copper loss6

%3. 7igh reactance "alues Lower reactance "alues%4. *otor temperature limit is %2&°# *otor temperature limit is %3&°#

PRICE

15. #ost effecti"e.*otor forging abo"e /3&mm dia has tobe imported 9upto )&1! : from7aridwar; ()&1! from *etaining rings to be imported from

Airforge; ?ranceSumitoma; =apan

#rukclockner;


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CONSTRUCTIONAL DETAILS OF TURBOGENERATOR

+AIN PARTS OF GENERATOR3

• STATOR Stator frame

Stator End covers Stator core Stator bars Stator indings Stator core suspension 7utput leads = brushings $emperature measuring devices Phase connectors

• ROTOR

(otor shaft (otor edges (otor coils (otor inding End inding bracings (etaining rings (otor fans >.- input lead connections Slip rings

• BEARINGS

Based on the principle of operation" the bearings are divided into to main categories.

$hese are8 'nti friction bearings1rolling element bearings3 Sliding contact bearings

Ant#02r#!t#on bear#n% are 2urther /#;#/e/ #nto3 Ball bearing -ylindrical roller bearings $aper roller bearings Spherical roller bearings 6eedle roller bearings

Sl#/#n !onta!t% bear#n% are 2urther /#;#/e/ #nto3

ournal Bearing $hrust Bearing


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lat/land thrust bearings $aper/land thrust bearings Pivoted shoe thrust bearings Spring mounted fle,ible plate thrust bearings$he bearings used in this type of generator are ournal bearings1one on either side of rotor shaft3

• COOLING SYSTE+

$here are mainly four types of cooling system depending upon the rating of the generator.$hey are" 'ir -ooling System1;*M+3 Hydrogen -ooling1%**M+3 +ater -ooling System1.- E,citation System1-onventional e,citation system ith >- e,citers3 Static E,citation System

• VENTILATION AND PROTECTION SYSTE+

• INSULATION

• VACCU+ PRESSURE I+PREGNATION

• E6CITER

• BRUSH GEAR

• STATOR

STATOR FRA+E$he stator frame is manufactured as a to part structure vi!. bottom part and top

part. $he to parts construction facilities assembly of caged core in the stator frame. $hestator frame is fabricated from the fusion elding #uality steel plates. $he stator frame isdivided into a no. of compartments 1 the cold air and hot air compartments 3 for aeffective flo of cooling in the frame .

$he frame structure is build up by the elding end plates and a no. of radial ribson to feet . $he end plates and radial ribs form the alls for different compartments. 'large no of a,ial ribs are provided beteen the compartments to provide sufficientrigidity to the frame to ith stand all mechanical forces arising out of different operating

conditions. $he stator frame is anchored to the foundation frame" hich in turns isanchored to the concrete foundation ith the help of foundation bolts and then grouted.Stator is of elded steel single piece construction ith radial and a,ial ribs having

ade#uate strength and rigidity to minimi!e core vibrations and suitably designed to ensureefficient cooling .guide bars elded =bolted inside the stator frame over hich the core isassembled . Incase of %


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5$ generators are suitably designed for open air as ell as -'-+ cooling . $heseframes are suitable for outdoor installations ith enclosure designed for the purpose. Incase of large capacity generators of 2PI design"the stator frames are of hori!ontal split casing structure to facilitate impregnation of stator and parallelmanufacturing of frame and stator core.

STATOR CORE

$he stator core is stacked out of thin electrical sheet steel laminations to minimi!ethe eddy current losses due to the magnetic flu,. Each layer of the core consists of a no of laminations segments. $he laminations are good magnetic properties and a lo lossinde,. $he laminations segments are punched from *.


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$he overhang portion of the bars are made to rest on insulating inding supportsand firmly secure to them ith glass sleeves= taps. $he top and bottom bars are connected by strip to strip bra!ing as per the inding scheme. inally all the ; ends of the 9 phasesare brought out. $he ound stator core is then impregnated in an impregnation tank under 2PI process. $he impregnation process involves the folloing stages8 Placing of the ound core in a tub and placing the tub in impregnation tank. Evacuation of entrapped air from the ound core by evacuating the impregnation

take. $hen completely immersing the ound core in mi,ture of epo,y resin hardener in

the tub. $hen applying high pressure to the impregnation tank so that the resin hardener

mi,ture penetrates into the voids in the ound core. $hen curing the ound core in a furnace at a specified temperature.+OUNTING OF CORE IN THE STATOR FRA+E

'fter the stator core is fully impregnated" it ill be assembled in the stator frame .to facilitate the assembly" feet are elded caged core rings. Supporting plates areelded in the stator frame beteen radial ribs. $hen the core is supported on the

supporting plates provided in the stator frame. $his sort of mounting arrangement illensure a sufficiently rigid core and at the same time some amount of damping takes placein the case of core vibrations.Tran%"o%#t#on Arrane&ent For The Stator Con/u!tor$he stator conductors are transposed by famous Aroebel transposition method. $heconductor is composed of to stacks of thin rectangular strips. Each strip is given tolinks edge ise to obtain 9;* transposition. $he position of the bends is so arranged thatit is possible to accommodate all the strips in the slot length of the machine or in other ords pitch for transposition is obtained by dividing the slot length by the number of strips. $he roebel transposition is done to ensure that all the strips occupy e#ual lengthunder similar conditionsof the flu, here by differential induction beteen the top and

bottom most strips are eliminated. Such an arrangement ill eliminate the losses in theconductor due to circulating current" hich ould have resulted in case of untransposedconductor.Stator En/ Co;er%$he end covers are the castings of the aluminum alloy and are bolted to the side platesof the stator frame. $he inlet passage is specially designed ith built in guide vanes"hich ensure uniform distribution of the air to the fan. 'ir ceiling is provided aroundthe shaft and at the parting plane of the top and bottom parts of the end covers so thatsuction of oil vapour from the bearings does not take place.En!lo%ure$he enclosure consists of the inner and outer components. $he inner components

comprises of the inding covers" hich from an angular enclosure of top and bottom parts and is designed as re#uired for particular degree of protection" as indicated in thedimension draing or in the A$echnical data. $he ventilating circuit is of the double/ended symmetrical arrangement. Ele!tr#!al Conne!t#on% o2 Bar% an/ Pha%e Conne!t#onBra!ing makes electrical connection of Bars8 Electrical connection beteen the topand bottom bars" one top bar being bra!ed to the associated bottom bar. $he coil


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connections are rapper depends on the machine voltage. 'fter tapping" an insulatingvarnish is applied. Pha%e Conne!tor%$he phase connectors consist of flat copper sections" the cross section of hich resultsin a lo specific current loading. $he connections to the stator inding are of rivetedand soldered type. $he phase connectors are rapped ith resin rich mica type" hichcontain synthetic resin having very good penetration properties. $he phase connectorsare then cured at a certain temperature" ith the shrinking tapes contracting so that avoid free insulation is obtained. Out"ut lea/%$he beginning and ends of three phase indings are solidly bolted to the output leadsith fle,ible. $he output leads consist of flat copper sections ith mica insulation. $o prevent eddy/current losses and inadmissible temperature rises8 the output leads are brought put.Te&"erature &ea%ur#n /e;#!e%

RTD% = F#re Dete!tor%• In stator inding" beteen bottom bar and top bar •

In stator core• In hot and cold air chambers• In bearing shell• ire detectors mounted on both sides of the stator core to detect fire inside the

generator.

• ROTOR

Rotor Sha2t$he rotor of turbo generator is single piece alloy steel forging" hich is forged

from a vacuum degassed steel casting. $he rotor consists of an electrically active portion1B'((EL P7($I763 and to shaft ends. 'n integrally forged coupling flange is provided to connect the rotor to turbine rotor.

$he operation re#uirements of the rotor are high mechanical strength and goodmagnetic properties as ell as freedom from defects. Mechanical" magnetic and 6>$tests are carried out on the forging to ensured the #uality re#uirements.

'ppro,imately ;*° of the rotor barrel circumference is provided ith longitudinalslots" hich house the field inding. $he unslotted portion acts as to poles" hich are%J* 1degree3" a part.

ROTOR COILS

$he rotor coils are manufactured from *.%N silver alloyed copper strips.Individual conductor is bent to obtained hal2 turn%) (ectangular cooling slots are punched on the conductor at regular intervals for the flo of cooling air. 'fter these half turns are inserted in to the rotor slots" these are braced together to from full turns. 'll theseries connected turn of one pair of slots constitute one coil. $hen different coils of rotor inding are connected in series such that one north and one south obtained.

$he inter/turns insulation beteen the turns is made of glass fiber laminate. $hecoils are insulated from the slot alls ith L/shaped strips of glass fiber laminate ithnome, filler. ' thick glass fiber laminate is inserted above the top most turn. $he total


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slot contents are then tightly secured by driving a edge in to the dove tail portion of therotor slot.

ROTOR SLOT EDGES

$o protect the inding against the effective of centrifugal force" the coils in therotor slots are firmly secure ith edges. $he material used for rotor edges shall havegood mechanical strength non/magnetic property and good electrical conductivity. $oachieve the above properties" cupro/nickel alloy dran profiles are used as rotor edges.$hese edges e,tend belo the shrink fit seating surface of the retaining rings. $heretaining rings" along ith the rotor edges ill acts as damper indings.ROTOR END INDINGS BRACING

$he spaces beteen different rotor coils in the end/inding region are fitted ith#n%ulat#n bra!er%. $hese insulating braces prevent the deformation = movement of individual coils and ensure the end inding as a single entity. $hese braces ill alsoguide the airflo so that intensity cooling of end inding takes place.

$he shrunk on hub at the free end of the retaining ring" serves to maintain thecircularity of retaining ring due to un/symmetrical loading by rotor end inding. ' snapring is provided for additional protection against a,ial displacement of retaining ring. 6on/magnetic" cold orked high strength alloy steel forging are used for retaining rings. 6on/magnetic material ensures reduced stray losses. Magnetic permeability 16on/magnetic property3

'nd 6>$ tests are conducted on the retaining ring forging to ensure the #uality of the forging. $he shrink fit surface of retaining is coated ith nickel aluminum silver toensure lo contact resistance beteen edges and retaining surface. $he retaining ringith their sink fit areas acts as short circuit rings of the damper inding system 1rotor edges acts as damper bars3.ROTOR FANS

$o a,ial flo fans located on the shaft at both ends circulate generator/coolingair. $he fan consists of aluminum alloy forge blades ith threaded roots. $he blades can be screed on to the rotor in hich threaded holes are already provided. $hreaded rootfastening permits the blade angle adustment. Each blade is secured at its root by lockingith a grub scre.Cool#n o2 Rotor #n/#n% Each turn is subdivided into four parallel cooling !ones. 7ne cooling !oneincludes the slot from the center to the end of the rotor body" hile another covers half the end inding to the center of the rotor body. $he cooling air for the slot portion is alimited into the slot bottom ducts belo the rotor inding. $he hot gas at the end of the rotor body is then discharged into the air gap beteen the rotor body and stator core through the radial openings in the conductors and in the rotor slot edges. $hecooling air for the end indings is dran from belo the rotor/retaining ring. It risesradically along the individual coils and is then discharged into the air gap. Rotor Reta#n#n R#n% $he rotor retaining rings ith stand the centrifugal forces due to the endindings one end of each ring is shrunk on the rotor body" hile the other end of the


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ring overhangs the end inding ithout contact on the shaft. $he shrunk on the hub atthe free end of the retaining serves to reinforce the retaining ring and secures the endinding in the a,ial director at the same time. $he shrink seat of the retaining ring issilver plated" ensuring a lo contact resistance for the induced current. $o reduce thestray losses and have high strength" the rings are made of non/magnetic core orkedmaterials.

(etaining rings firmly secure the rotor indings from the effect of centrifugalforces during operation one end of the retaining ring is shrunk on to the rotor body" hilethe other end of the retaining ring over hangs the end inding ithout making anycontact ith shaft. $his ensures an un/obstructed shaft deflection.Sl#" R#n%$hese are made of forged steel and shrunk on either side of the rotor beteen the endcover and the bearing. $he mica splitting is used to insulate the slip rings from therotor body. $he e,citation to the rotor inding is taken from these slip rings. $heconnection leads are suitably insulated and taken through slots milled on the surface of the rotor. +edges are provided to keep the leads in position. ' helical groove ismachined on the outer surface of the slip rings to have better dissipation of heat" thusminimi!ing the brush ear.Slip rings are provided for turbo generators ith conventional >- rotating or statice,citation system. $hese are of alloy steel forgings shrunk fitted on the rotor shaft and areinsulated from the shaft. for the rotor earth fault protection" the rotor is provided ith anadditional brush" hich is fi,ed to the bearing on the drive side and is in contact ithrotor shaft during operation. (otors are dynamically balanced to eliminate unbalance andvibration in operation. 7ver speed test at %)* percent of rated speed for ) minutes iscarried out to ensure mechanical soundness of the rotors.Rotor Balan!#n$he rotor is balanced ith the help of sophisticated balancing machine. $he balancingeights are provided in the hubs under retaining rings and in the fans. $he rotor isdynamically balanced and subected to an over speed of )*N for )min. F#el/ Conne!t#on%$he field connections provide the electrical connection beteen the rotor inding andthe e,citer.Ternal Lu%-onsists of a copper conductor of rectangular cross/section. 7ne end of the terminallug is bra!ed to the rotor inding" hile the other end is screed to the radial bolt.Ra/#al Bolt$he field current lead located in the shaft bore is connected to the terminal lug througha radial bolt. $he radial bolt is made from steel and screed into the field current leadinto the shaft bore.

• BEARINGS $he turbogenerators are provided ith pressure lubricated self aligningellipticaltype bearings to ensure higher mechanical stability and reduced vibration inoperation .$he bearings are either end shield mounted or pedestal type.suitabletemperature element devices are mounted in the bearings to monitor bearing metaltemperature in operation.


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$he rotor shaft is supported in sleeve bearing having forced Coil lubrication. $he bearings are located in bearing pedestals. $he oil re#uired for bearing lubrication andcooling is obtained from the turbine oil supply system and supplied to the lubricating gapvia the bore in the bearing pedestals and via grooves in the loer half of bearing shells

$he loer bearing shell ith its self C alloying outer surface rest on the bearing pedestals. $he E.S. bearing pedestal is insulated to prevent the flo of shaft currents andto provide for insulation oft the generator bearing from ground. $he pipes flanges to the bearing pedestals are like Cise insulated from the bearing housings. ' tangential stopper is provided at the bearing shell parting plane to prevent the bearing shell from turning in the pedestal.

$he inner surface of the cast bearing sleeve body is provided ith spiral a dovetail groove hich firmly holds the Babbitt liner to the bearing sleeve body. $he loer bearing sleeve has grooves to admit the lube oil on to the bearingsurface. $he upper sleeve consists of a ide over flo groove through hich the oil isdistributed over the shaft ournals and fed to the lubricating gap. $he oil is drainedlaterally from the lubricating gap" caught by baffles" collected in the bearing pedestalsand returned to the turbine oil tank.

'll the generator bearings are provided ith a hydraulic shaft lift oil system toreduce bearing friction during start/up and turning gear operation. High Cpressure oilforced beteen the bearing surface and the shaft ournal" lifting the rotor shaft to allothe formation of a lubricating oil film.

$he bearing temperature is monitored ith ($>Fs located appro,imately in the plane of ma,imum oil film pressure. $he ($>s screed in position on one side of theloer bearing sleeve from out side ith the detector e,tending up to the Babbitt liner.BEARING INSULATION

$o prevent damage to the ournals due to shaft currents" bearings and oil pipings on either side of the non/drive end bearings are insulated from the foundation frame. or facilitating and monitoring the healthiness of bearing insulation" split insulation is provided.

• VENTILATION AND PROTECTION SYSTE+

Vent#lat#on an/ Cool#n$urbogenerators are designed ith the folloing ventilation systems8-losed circuit air cooling ith ater=air coolers mounted in the pit.-losed circuit hydrogen cooling ith ater=hydrogen coolers mounted a,ially on thestator frame.$he fan designusually consists of ) a,ial fans either of cast aluminium ith integralfan blades or forged and machined aluminium alloy blades screed to the rotor.In the case of %


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$hese heaters are used to circulate arm air inside the turbo generator and duringoutages to prevent condensation of the moisture inside the machine. $hey are of striptype and robust design. $he heating elements are enclosed in a steel sheet ithspecific rating of %


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$hese protections are supplemented ith additional protections like pole slipping protection and stator earth fault protection covering %** percent inding.

COOLING SYSTE+-ooling is one of the basic re#uirement of any generator. $he effective orking of

generator considerably depends on the cooling system. $he insulation used and cooling

employed are inter/related.$he various losses in the generator are broadly classified as belo.%. Iron losses = -ore losses = Magnetic losses = -onstant losses). Hysterisis Losses9. Eddy current losses&. -opper losses = IO)( losses = +inding lossesirect forced38 upto%irect forced38 upto)


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H$/roen !ool#n ha% the 2ollo'#n a/;antae% o;er A#r !ool#n

%.Hydrogen has Q times more heat dissipating capacity.).Higher specific heat.9.Since Hydrogen is %=%&th of air eight. It has higher compressibility.&.It does not support combustion.D#%a/;antae%%. It is an e,plosive hen mi,es ith o,ygen.). -ost of running is higher.9. Higher capacity generators need better cooling system.

$urbogenerator is provided ith closed circuit air/cooling system. $he heat losses arisingin the generator interior are dissipated to the secondary coolant 1cooling ater3throughair.DIRECT COOLING

>irect cooling of the rotor essentiality eliminates hot spot and differentialtemperatures beteen adacent components hich could results in mechanical stresses" particularly to the copper conductors" insulation and rotor body. Indirect air/cooling isused for the stator inding.AIR0COOLING CIRCUIT

'I( 2s H?>(75E6-77LE>8

I$EM 'I( H?>(75E6

-urrent >ensities Loer Higher

lu, >ensities Loer Higher

Losses Higher Loer

Efficiency Loer Higher E,citation

re#uirement Loer Higher

Heat transfer Loer Higher

0g=02' Higher Loer

-ost=02' Loer Higher 7perational

Ha!ard 6ill E,its$ime of Starting=

Stopping Loer Higher

'u,iliaries 6ill E,its

Maintainence -ost Loer Higher


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$he cooling air is circulated in generator interior in closed by to a,ial flo fansarranged on the rotor shaft. -old air is dran by the fans from the cooler compartments.$he cooling airflo is divided into three flo paths after each fan.AIR COOLER

$he air cooler is a shell and tube type heat e,changer" hich cools the air in thegenerator. $he heat removed from the cooling air is dissipated through the cooling ater.$he cooling ater flos through the tubes" hile cooling air passes around the finnedtubes.Si, identical cooler elements are provided in an air cooler unit" hich is mounted" by theside of the generator. 7ut of the si, elements five elements are sufficient for operationand one element is spare. $he spare element is closed on airside ith a L'P. 'nyelement can be made spare by shifting the L'P to that element.

Each element is provided ith a gate valve in the ater inlet line and one globevalve in the ater outlet line 1Hot ater line3.$he re#uired cooling ater flo depends on the generator output and is adusted byregulating the valve in the ater outlet line. -ontrolling the cooling ater flo on theoutlet side ensures an uninterrupted ater flo through the cooler elements.$he air cooler unit is provided ith a make up air filter. $he air filter provides a loresistance path to atmosphere air" hich enters to make for any leaked air. $he make upair is cleaned by the air filter before it enters the generator cooling air circuit.SYNCHRONOUS GENERATORS0 LOSSES AND COOLING'll electrical machines produce heat oing to various losses generated inside themachine 1like the I)( losses of stator copper inding3. $hese losses are categori!ed asfi,ed and variable. riction and indage losses" hich include hysterisis and eddycurrent losses" are all considered to be fi,ed losses hile the rotor copper losses" aretreated as variable losses. riction and indage losses are dependent upon speed andas synchronous machines run at constant speed" these losses are constant. 's themagnetic flu, passes through stator laminations" hysterisis and eddy current lossesresult in and are dependent on the magnitude of flu,. 's long as machine is delivering poer at a constant voltage" hich is normal case" these losses in the laminations are

fi,ed. $he stator copper losses and rotor copper losses vary in s#uare proportion to thestator and rotor currents respectively. $hese currents vary in accordance ith the loadand thus in turn the losses also vary and hence termed as variable losses.

• -ore = Magnetic losses1constant ith voltage3• -opper = inding losses1variable ith load3• Bearing friction : indage losses1constant ith speed3

's the synchronous machine has to deliver the output continuously" the heatgenerated inside the machine has also to be taken aay at the same rate so that themachine can operate at a stable temperature continuouslyD ensuring a longer life for the insulation system hich in turn ensures a longer life of operation of the generator

itself.5enerally 4pto %)< M2' air/cooling is employed.Hydrogen cooling is employed in the machines i.e." above %)


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cooling and this open air/cooling is employed for the 5as turbine generators herethere is scarcity of ater.

INSULATION

In electrical machines insulation is most important re#uirements to sustain high voltagesand basically insulation is the heart for electrical machines. 'ny insulation should havehigh dielectric strength " good thermal conductivity" and high mechanical strength.Insulation is the property " hich has enormous resistance to the flo of current.it is basically the forbidden gap beteen valence and conduction bands for these insulation isvery high.$he property of insulation material is non conductive to electricity andconductive for heat. $he high voltage insulation is provided" ith thermosetting system. $hehigh voltage insulation is particularly voided free and characteri!ed by e,cellentelectrical" mechanical and thermal properties. $o prevent corona discharges beteen the

insulation and the slot all" a final coat of conducting varnish is applied to the surface of all bars ithin the slot range. 'll bars are additionally provided ith an end corona protection to control the electrify field at the transition from the slot to the end inding portion and to prevent the formation of creep age sparks.

le,ible hardened glass laminates ith suitable resins are used as interturninsulation. $he insulation is thermally consolidated to form a compactness capable of ithstanding mechanical forces in operation generators of %


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%.$hermoplastic process of insulation). $hermosetting process of insulation.$hermosetting process of insulation is basically of to types. $hey area9 Ther&o Rea!t#;e Re%#n R#!h S$%te&b9 +#!al#%t#!0VPI re%#n "oor %$%te&

a9Ther&o Rea!t#;e Re%#n R#!h S$%te&8

$he system is class $hermo reactive epo,y mica paper employing stage Bimpregnated epo,y mica resin rich tape" hich is consolidated under heat and pressure.In this system" stage B epo,y mica tape material has limited shelf life and re#uirescontrolled condition of toer temperature storage.

$his system provides the usage of resin rich polyester backed epo,ymica folium on straight portion and resin rich polyester backed epo,y mica paper tape onoverhang ith a final layer of polyester shrink tape. $he system is highly productiveduring coil manufacture and housing.

$he ound stators are totally impregnated in unsaturated polyester resin throughrolling techni#ue. or bra!ing of coils" usage of oven polyester felt around moldedcasting is in common" hich provides bond beteen coils after impregnation. Insulationthickness in mm adopted for main insulation is much less in comparison to (esifle,insulation system.b9 +#!al#%t#!0VPI Re%#n Poor S$%te&3 Micalistic class F insulation system is based on resin poor technology. $his consists of high strength mica and thermo/setting solvent/less epo,y resin ith vacuumimpregnation. $he system employing elaborate manufacturing facility gives higher valueof production and more consistent #uality because of lesser manual operation and moreautomation.(esin poor micalistic system is adopted for large range '- insulation and synchronousmachines. $hese are designed to meet specific customer re#uirement hence are uni#ue innature to each other. $he main insulation consists of resin poor epo,y mica paper tape allover the coil periphery ith varying number of layers on straight and overhang portions.$he ound rotors are impregnated under vacuum to avoid free monolithic thickness areslightly higher than those used for resin rich Micalistic insulation system. $his systemsatisfies class F re#uirements but being thermally utili!ed to class BF temperature only"therefore there is a thermal reserve" hich results in%3 Prolonged life)3 Increased reliability93 -apacity for occasional overloadThe !o&"ar#%on bet'een re%#n r#!h an/ re%#n "oor #% a% 2ollo'%

Re%#n "oor Re%#n r#!h

%3 Epo,y resin content is about JN %3 Epo,y resin content is about &*N)3 $his method follos thermo setting process

)3 $his method follos thermo setting process

93 'ddition of resin from outside is needed 93 urther addition of resin is not re#uired&3 (eduction in time cycle for this process &3 It is very long process and time

consuming


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Q3 6o test is carried out here on bars Q3 $ests are being carried out hile processing such dielectric test and highvoltage1H23 test.

-ommittees and organi!ations that set standards have grouped insulators into five classes"depending upon their ability to ithstand heat. $hese classes correspond to the ma,imumtemperature levels of8 %*


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$he above insulation classes indicate a normal life e,pectancy of )* ***h to &* ***h atthe stated temperature. $his implies that electrical e#uipment insulated ith a class 'insulation system ould probably last for ) to < years if operated continuously at %*!#terIt has a frame" hich accommodates the laminated core ith the three/phase inding.$he rotor consists of a hub ith mounted poles. Each pole consists of separate

magnets" hich are housed in non/magnetic metallic enclosure. Three0"ha%e +a#n E>!#terIt is a revolving armature unit" the frame poles ith the field and the damper inding.$he field inding is arranged on the laminated magnetic poles. $he rotor consists of stacked laminations" hich are compressed through bolts over compression rings thethree/phase inding is inserted in the slots of the laminated rotor. $he indingconductors are transposed ith in the core length and the end turns of the inding are


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secured ith the steel brands. $he inding ends are run at bus ring system to hichthe three/phase leads leading to the rectifier heels are also connected. 'fter fullimpregnation ith epo,y resin and curing" the complete rotor is shrunk onto the shaft.AC E6CITERS$he ac e,citer are a specially designed Ainduction type alternator ith no inding on itsrotor. $he armature :field inding are accommodator in the stator .the e,citer is usuallydesigned to operate at high fre#uency to reduce the si!e of the machine .the armatureterminals of ac e,citer are connected to field inding of generator :series field indingof ac e,citer through a field breaker .the magneti!ing :demagneti!ing field indings of ac e,citer are controlled by '2(. $he poer re#uired by '2( is provided by a permanent magnet generator. Since there is field inding on the rotor of '- e,citer" the ac e,citer proved to be very reliable in operation. $hough this system eliminates all problemsassociated ith commutator" it is not free from problems attributable to slip rings :its brush gear .the brush less e,citation system provided the anser for all these problems.ormer practice no almost absolute is due to the folloing disadvantages8

%. ' no. of e,citers operating in parallel supply the e,citation bus). $he layout of station ill be much complicated9. $he e,citation of the failed ac generator '- generator is to be supplied

by the remaining ac generatorsE6CITATION SYSTE++hen a generator operates" alone the e,citation is controlled to maintain the steady statevoltage ithin the necessary limits and to prevent unacceptable variations of voltagehen large and sudden changes of load occurs. 5enerators running in parallel may needadditional control signals to share the total reactive load correctly beteen them. Ininterconnected system control of steady : transient stability is a vital duty .$he basicfunction of the e,citation system is to provide the re#uired dc field currents to magneti!ethe rotor of turbine generator .the e,citer is generally a four pole or a si, pole revolvingfield ac generator" hich operates in saturated path of its characteristic" to maintainlinearity beteen generator slip rings voltage :controlled e,citation of main e,citer.Generator% !an be %u""l#e/ '#th an$ o2 the 2ollo'#n e>!#tat#on %$%te&%

%3Brush less e,citation system• -onventional e,citation system• 7ver hang e,citation system

)3Static e,citation system93-onventional e,citation system ith >- e,citers1>c e,citation system3

I&"ortant !hara!ter#%t#!% o2 E>!#tat#on S$%te& are3 i3 Tuick response of the e,citer to the '2(. $he response is measured in terms ofnominal e,citer response.

ii3 High ceiling voltage.Nonal e>!#ter re%"on%e ? %lo"e o2 %tra#ht l#ne)

Nonal !olle!tor r#n ;oltae)

+a#n Feature%'n e,citation system ith rotating rectifiers consists of an au,iliary e,citer ith rotating permanent poles and a main '.-.e,citer ith a stationary magnet system and a rotating 9 phase '.-. inding to hich silicon rectifiers are connected.


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$he rotors of these to machines are coupled direct to the shaft of the main generator. 'sin the case of direct coupled >.-.e,citers" this makes the e,citation circuit independentof any e,ternal au,iliary system.The &a#n a/;antae% o2 th#% e>!#tat#on arrane&ent are 3

• 6o commutators• 6o slip/rings

• 6o carbon brushes• 6o pollution by carbon dust• Minimum maintenance• High reliability.

Sele!t#on o2 E>!#tat#on Voltae an/ Current3

$he voltage :current rating of the e,citation system is selected in order to give thefolloing8() $o give field inding conductors that is mechanically robust in small machines : toomassive in large machines.-) Suitable the ratings of available diodes or $hyristor.5) $o give convenient design of e,citer :of slip rings here these are used.

:) 't no load or ith leading pf" control of the e,citation current is needed to comedon to about %=9 of the value for rated load.$he e,citation system must respond to applied signals #uickly enough to have the desiredeffect on the generator flu, It duties can be broadly classified as• $o control the generator voltage accurately as slo changes of poer and reactive

loading occur.• $o limit the fluctuations of voltage hen loads are suddenly imposed or removed.• $o maintain steady state stability :transient stability• TYPES OF E6CITATION SYSTE+S

a9 Bru%h le%% e>!#tat#on %$%te&

$his system comprises shaft driven '- e,citer ith rotating diodes" permanent magnet generator and '2( .$his system is highly reliable ith leastmaintenance and is ideally suitable for gas turbine driven generators.

In this method the collector brush gear" the commutator brush usedconventional e,citation systems are eliminated. brushless ac generator has its e,citation poer supplied to the field indings from the rectified output of a direct coupledrevolving armature of ac e,citer. $his re#uires the rectifier is to be mounted in hub" hichrotates ith shaft : necessities the omission of main field suppression e#uipment thisinivation introduces a much shorter e,citer time delay due to a fact that a conventional>- e,citer is replaced by a high fre#uency. $he smaller time delays the system easier tostabili!e :improve the overall system response.B)L) E>!#ter%

• 6o brushes• ' rectifier heel converts the ac output of the BLE armature to dc.• $hey are either coupled or overhanged mounted)

Con%tru!t#onal Feature%

• It is also another generator • $he field is on the stator unlike the turbogenerator.• $he armature is on the rotor.


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• 'll the brushless e,citers have inbuilt = separately mounted PM5FS.A/;antae% o2 Bru%hle%% E>!#tat#on S$%te&%

() High reliability-. Minimum maintenance5) Immunity from environment:) 6o poer cabling

D#%a/;antae%

() 6o generator field breakers-) 6o direct field currents :temperature measurements5) Presence of additional rotating machine in the system

Bru%h le%% E>!#ter@% No&en!lature3

E ' ( !#ter% 8DC e>!#tat#on %$%te&9

$he e,citer as a dc generator coupled to the shaft of the synchronous


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machine" feeding its output to the main field through slip rings. -onventional >.- E,citation Systems ith a >.-. e,citer enoyed anunchallenged position till recently as adopted universally for all alternators. +ith thegroth in unit si!e of large capacity >.-. e,citers capacity became necessary. >ue to problems in communication it became inevitable to design of large capacity >.-.e,citers at lo speeds leading to increase in the systems. Moreover" the >.-.e,citation suffered from problems like C poer cabling" problems associated ithcommutator and brush gear and maintenance.+ith the advent of high poer solid statesemiconductor devices" significant strides ere made in the development of nee,citation systems and thus in order to li#uidate the communication and brush gear problems of the >.-" the '.- e,citers ere introduced.

A/;antae% o2 Con;ent#onal E>!#tat#on S$%te& 8%. 'vailability of e,citation poer even if the poer supply or '2( failures). Economical9. 5ood e,citer response&. Measurement of field is possible.D#%a/;antae%

%. Maintenance of brushes.). -ommutator problem9. E,tensive poer cablingE6CITATION SYSTE+ ITH DC ROTATING E6CITER

In these e,citation systems" dc e,citer is connected to the field inding of turbo generator through a field breaker. -urrent through e,citer field inding is controlled by anautomatic voltage regulator depending upon generator voltage :load parameters. the parameter magnet generator provides ac poer supplies :hence the system is veryreliable .this inding provides about Q*c of e,citation poer is provided by the secondinding is connected to '2(.

4sually up to!#tat#on3Systems are classified into to types as8High re#uency E,citation System as developed. 't present this is the system"hich is idely used oing to its reliability" good transient performance and leastmaintenance. $he system also doesnFt suffer from the problems of communication" brush gear and poer cabling. Hoever" the main disadvantage of the system is thatthe rotor is not accessible and thus fast de/e,citation" in case of any fault on rotor

inding" is not possible.Static E,citation System as developed contemporarily as an alternative to brush lesse,citation system. $his system makes use of generators upto %;* M2'. $he system hasgot an e,cellent transient response. But the system is not free from the poer cabling"slip rings" brush gear and moreover the e#uipment and thus the layout of the cubical arenot compact.

PER+ANENT +AGNET GENERATOR8P+G9


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$his is a very small 9 phase synchronous generator " in hich armature indings arelocated in the stator and the rotor is provided ith permanent magnet poles .Since permanent magnet poles are provided " no field inding1or e,citation3 is re#uired. +iththe help of PM5" the generator can build up voltage in the absence of any >- e,citation.$he 9 phase '- produced in the PM5 stator is rectified and fed to the main e,citer fieldthrough an '2(.$he PM5 is also a high fre#uency generator" generally at %uration8 K%;/%J Hours

• Entire stator assemblies are immersed into li#uidthermosetting epo,y resin insulation and vacuum/pressureimpregnated.

• (esin $emp8 ;*>E5. - =/ )>E5. -" (esin ill K )* min (esin Level8 %** mm 'bove ob" Settling $ime K %* min• Pressuri!ation8

6) Pressure K & bar" (aising $ime K J* min Holding $ime8 ) Hours.• (esin is ithdran back

Chara!ter#%t#!% o2 VPI #n%ulat#on %$%te&3

%3 Higher mechanical bond)3 2oid free resin ith high mica content ensures better heat transfer.93 High dielectric strength" lo dissipation factor" hence longer electrical life.&3 Higher thermal stability" ensures class/ under running conditions.


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dried and the impregnated in a resin bath under pressure of nitrogen gas. $hen the stator is cured in an oven.

$he main characteristic if this system of insulation is also follos8%. Better heat transfer resulting from resin penetration into minute air gaps in beteen

laminations and bar insulations.). Lo dielectric loss resulting in increased life of the machine.9. High resistance against the effect of moisture.&. (eduction of time cycle of manufacture.

VACUU+ PRESSURE I+PREGNATION PROCESS8

our stages of 2acuum pressure impregnation cycle %3 vacuum drying8

temperature 8 ;*oc =/ 9oc

pressure 8 *.) millibar duration 8 K %;/%J hrsdrying check8 *.*; mbar drop in %*min

)3 Imprgnation8resin temperature 8 ;*oc =/ )ocresin filling 8 K )* min

resin level 8 K %** mm above settling time 8 K %* min

resin 1epo,y bisophenol Ca3 : hardener ratio %8%

93 Pressurisation8 6) pressure 8 K & bar rising 8 K J* minholding time 8 K ) hrscapacitance measurement to ensure effective peneteation and gelling

&3 Post curing8temperature of ob 8 %&*oc =/


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• Lo inflamability• Higher resistance to effect moisture• Higher chemical resistance to corrosive gases"lubeoils"acids:alkalis.• Lesser manufacturing cycle of machine.• Higher p= ratio "loer cost of machines.

BRUSH GEAR

In order to effectively supply e,citation current to the rotor inding" the brush gears arerobustly designed ith radial type brush holders. Brushes of natural graphite compositionith lo co/efficient of friction and self/lubrication properties are used" hich ensure

smooth and trouble free operation. $he brush gear is either fi,ed on to the end of thestator end covers or bearing of is mounted separately on a pedestal. >epending on there#uirements" generators are provided ith on/load brush changing gears.The a/;antae% o2 th#% arrane&ent are3

constant spring tension over the entire brush ears. Brush changeover ithout stopping the machine. safety of the personnel due to provision of insulated handle.

INTRODUCTION TO TESTING OFTURBOGENERATOR

$esting is an activity" hich basically evaluates a component" and or a product 1built up

of component assemblies3 as to hether it has the technical capability that has been builtinto it by ay of design" materials" and technological processes employed hilemanufacturing and orkmanship.'s such" testing activities can broadly be classified in to a number of categories asfollos8

• $ype tests.

• (outine tests.

• Process tests.

• Prototype tests.

• (andom sampling tests.• Endurance tests.

• (esearch and development tests.

• Environmental tests.

• Investigatory : maintenance tests.

• 'cceptance tests.


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• -ommissioning : site tests.

TESTING OF TURBOGENERATOR

WW Measurement of dc resistance of stator and rotor inding.W Insulation resistance of stator inding.W Insulation resistance of rotor inding.W High voltage test.W Phase se#uence test.W >etermination of o!!)W >etermination of %!!)W 7verspeed test.W Efficiency determination by separation of losses.W 2ibration measurements.

W Impedance test of rotor inding.W Heat run test of rotor inding.W Heat run test in mechanical"%!! and o!!)W Sudden three phase short circuit test.

A/;antae% o2 te%t#nProvides #uality assurance.Meets the re#uirements of legal : contract re#uirements.(eduction in reork cost.Ensures process capability : develops checklist.Increases confidence levels in manufacture.Provides data for optimi!ation of design.

Helps in building of Safety : general 7:M manual.Establishes control over ra materials.I&"ortant "o#nt% 2or te%t#nHave an approved procedure.$abulate test levels = stages.-heck the testing e#uipment before use.-alibrate the test e#uipment : instruments.Ensure interlocks of the e#uipmentLog the results in proper formats.'nalyse failure : submit a comprehensive report for repair = replacement.

PERFOR+ANCE TESTS ON TURBOGENERATOR3

+ith the increasing trend on standardi!ation every country has its 6ational Standardscovering a ide range of subects" In India" the Indian Standards are valid andapplicable. $he machines produced at Hyderabad fully conform to Indian and alsoInternational Standards" and many machines are being e,ported to various countries. $he performance tests on turbo generators include the folloing


33/55

• Measurement of Insulation resistance.• Measurement of ohmic resistance of indings in cold state.• 'pplied H.2. tests.• Measurement of vibrations and mechanical losses.• Measurement of no load characteristics.• Measurement of short circuit characteristics.• >etermination of e,citation on load and checks of voltage rise 1regulation3.• Measurement of leakage and potier reactances.• Measurement of losses and determination of efficiency.• Heat run tests.• (etardation test.

Te%t#nRout#ne Te%t%

• >- cold resistance• Mech. run : vibration meas.• Meas. Shaft voltage• Meas. 7f rotor Impedance• I( test of st : rt indings• H2 test of st : (t indings• Phase Se#uence• Meas. 7f PI of stator inding

• Mechanical Balance• 7ver speed test 1%)*N3• >etermination of X by separation of losses method• 7-" S- test

T$"e Te%t%• $emperature rise test• Sudden 9Y S- test• >etermination of reactance : $ime const.• 2oltage +aveform

TEST PROCEDURE>uring manufacturing of $urbo/generators the folloing stage tests are to be carried outon individual components to ensure #uality of the product and to reduce last minutedelay during acceptances tests. $he standards for these tests ill differ from plant to plant.Stator

• -hecking up of (esistance temperature detectors hile core building.• (ing flu, test.


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• $an delta measurement on stator inding after impregnation.• H.2. test on coils during manufacturers and assembly.• -apacitance measurement.Rotor

• H.2. test on e,citation connecting leads.• H.2. : inter/ turn insulation tests on field coils during the inding process.

• Impedance measurement field coils.O;er0%"ee/ te%t

7ver/speed test involves mechanical running of the rotor at the prescribedN over/speed for the stipulated period of time. It is later subected to a veryclose mechanical inspection to investigating into the effects of over speed if any.$he rotor is balanced to the re#uired levels as per standards. $his brings us tomeasurement of characteristics and losses of the generator.Measurement or determination of efficiency of the machine is an important step.or determination of efficiency" losses measurement on the drive system is to be done and

derive machine losses by subtracting drive motor losses.Deternat#on o2 e22#!#en!$Having measured the losses" the efficiency can be estimated from the formula.Efficiency 1input Closses = input output = 17utput losses3$olerance on guaranteed efficiency is *.% 1%/efficiency3 hen measured by summation oflosses method.+ea%ure&ent 2or leaae = "ot#er rea!tan!e Leakage reactance is measured on the stator alone hen inding is completed. $he procedure involves supplying the inding from a 9/phase variable voltage source andmeasuring currents voltage and poer at the stator terminals. >epending on the sourcecapacity upto *.)


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+here 2o 2oltage from measured in open phase voltage and Io is current measured inline to neutral during line to line sustained short circuit test.Retar/at#on te%t 2or /eternat#on o2 +o&ent o2 Inert#a$he machine speed and time are noted during free coasting don of the machine.Moment of inertia 1& , 9;


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$he rotor coils and their insulation are subected to a high stress hen in normaloperation. $hus a thorough inspection of these is necessary before putting them in therotor slots as otherise any replacement of the faulty insulation or cell ouldnecessitate removing the coil binding rings and the edges" hich is a cumber ob. 'series of graded voltage tests are conducted on the rotor cell and coils dusting assemblyand also hen finished to test its electrical strength against likely creep age to ground or inter turn breakdon.Te%t% On The Rotor Co#l%%. Bet'een turn%$he rotor coils turns are made up of a number of turns hich are formed in halvesand then assembled ith their inter turn insulation and boned ith an adhesive in thesteam heat press. 'lthough the normal orking voltage per turn is very small" a turnto test of )&* volts is done to e,ercise #uality control.

).To" turn trouh$he insulation the top and bottom of the rotor slot provides ade#uate and safe creepage distance beteen copper and rotor steel" in case of slotted copper


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O;er S"ee/#nIn order to check the soundness of all parts and fitting on rotor assembly" the rotor isrun at an over speed of %&N for five minutes or 9*N for one minute. PERFOR+ANCE TESTS7 TESTS ON CO+PLETED +ACHINE3$he machine is assembled and erected at the heavy rotating plant test bay for test. Dr$ out #n%ulat#on re%#%tan!e o2 rotor = %tator '#n/#n%

• Before starting ith running tests" the stator indings are dried out bycirculating current in the inding from an e,ternal dc source Input of poer isso controlled as to limit the temperature of the end indings to a ma,imum of J**- by thermometer.

• Progress of dry out is observed by one minute insulation resistance readingith %***v Megger. +ith the application of heat" the insulation resistance illinitially drop and then ill rise again over a period of time and finally becomesappro,imately constant temperature. (ation of ten/minute reading i.e. polari!ation inde," hen more than ) gives an indication of good dry out.Insulation resistance readings of rotor inding to ground are taken.

Re%#%tan!e o2 &a!h#ne '#n/#n%

Measurement of cold inding resistance" both for stator and rotor must be veryaccurate since it forms the basis of-alculating copper under cold and hot conditionsor determining the rise in temperature of rotor inding by resistance method at theend of temperature test.'ll precautions are taken to ascertain correct temperature of the inding hitemeasuring cold resistance. Since the inding resistance of turbo generator is #uitelo8 a modified form of heat stone bridge i.e. 0elvinFs double bridge does aayith the necessity of accounting for the resistance of loads. (esistance beteen phasesfor stator and beteen slip rings for is recorded along ith the cold indingtemperature at the time of measurement.Pha%e %euen!e te%t

$he phase se#uence test is to check the agreement of the terminal markings that have been specified using the Phase Se#uence Indicator.

ero e>!#tat#on rate/ %"ee/ runBy attmeter method hen condition is steady. rom the result of above test after deducting drive motor in gear losses" friction and ind age losses of the machineunder test are computed. $hese losses are for rated speed. Bearing oil #uantities ithinlet temperatures of oil can yield calculations for bearings loss. rom a previous dataon seal face losses determined from a prototype test" the total friction loss in the bearings and seals can be difference. Since bearing loss is computed for design officeuse by the difference. Since bearing loss goes to oil" any heat carried out on theune,cited machine ill give temperature rise due to ind age.PERFOR+ANCE TESTS

$he performance tests on the turbo generator are classified as8/ $ype tests/ (outine tests/ Heat run tests


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TYPE TESTS$hese are specially re#uested tests form the customer. $hey are not performed on allmachines i.e." they are specific to machine. $hey include

/ Mechanical measurement of leakage reactance of stator inding/ Measurement of residual voltage of stator inding at rated speed/ Line to line sustain short test and determination of negative se#uence

reactance Z@)[/ Line/to/line and neutral sustain short circuit test and determination of

negative se#uence reactance Z@7[/ (etardation test for determination of 5>) +ea%ure&ent o2 leaae

rea!tan!e o2 %tator '#n/#n/ $his test is done on the stator inding ith out rotor" generally before

assembly on test bed for running test./ Pur"o%e

• $o determine total leakage reactance• $o determine potier reactance• $o determine armature leakage reactance

$o determine leakage reactance" a search coil of ade#uate number of turns isinstalled securely ith in the stator bore ith a fle,ible and ell/insulatedcopper ire. $he coil span shall be of full pitch ith all four sides as closely incontact ith fore as possible if one side of the coil is on the top of slot no one"the other side of the coil shall be on the top of the slot number n.here" n Ztotal no. of slots = total no. of poles[ %

'fter connecting meters" variable voltage is applied to the stator indings such thatthe stator current reaches to 9*N of rated current or ma,imum capacity of thyristor sethich ever is less and meter reading are noted don.

1a3 Evaluation of leakage reactance1b3 $he different leakage reactanceFs are evaluated as follos8i3 Base impedance Z@n[ En = \9In ohms

here En rated line to line voltageIn rated line currentii3 $otal armature leakage reactance Z@L[ \1G) C ( )3 here G 4= \9I" ( P= 9 I)

4 voltage measured during the test I current measured during the test P poer measured during the test

's the value of ( i.e." stator inding resistance per phase is negligible comparedto G" measurement of P is not re#uired.@L G 4= \ 9 I ohmsN @L %**1@L = @ 63iii3 Potier reactance N @P a 1 N @L3here a % for salient pole machine and *.;9 for cylindrical pole machineigure &.% Single line diagram of measurement of leakage reactance


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+ea%ure&ent o2 re%#/ual ;oltae o2 %tator '#n/#n% at rate/ %"ee/'fter the open circuit test" the machine is gradually de/e,cited and the residualvoltages of stator indings are measured at rated speed" across the three phases.L#ne0to0l#ne %u%ta#ne/ %hort !#r!u#t te%t an/ /eternat#on o2 neat#;e %euen!erea!tan!e

$he line/to/line sustained short circuit test is carried out by short circuiting and toline terminals of the stator inding using current transformer ith the machine drivenat rated speed and e,cited. $he folloing parameters are recorded at three values of the short current limited to 9*N at rated current.

/ Short circuit current 1I0 )3" through current transformer / 2oltage beteen the open line terminal and one of the short circuit terminals

4k )" through potential transformer./ 'ctive poer p.

E;aluat#on o2 neat#;e %euen!e rea!tan!e 86-91i3 @) P = 9. 1I 0 )3) ohmshere P poer measured during the test I0 ) line/to/line short circuit current measured during the test N@) %**1@)=@n3

L#ne0 to0l#ne an/ to neutral %u%ta#ne/ %hort !#r!u#t te%t$he line/to/line and neutral short circuit test is carried out by short/circuiting to lineterminals and shorted to the neutral using current transformer. $he machine is drivenat rated speed and e,cited. $he folloing values are recorded at several values of shortcircuit current.

/ 6eutral current 1Io3" through the current transformer / 2oltage beteen the open line terminal and neutral 12*3 through potential

transformer E;aluat#on o2 ero %euen!e rea!tan!e

Gero se#uence reactance is calculated as follos8

@7 27 = I7 ohmshere 27 line to neutral voltage I7 line to neutral current measured during the test N @o %** 1@o = @n3

6ote8 Minimum time is taken for the test because serious overhang inding heatingmay result" if current is sustained for a longer time or raised to too high a value.Re/ar/at#on te%t 2or /eternat#on o2 GD- 15ravitational deterioration3$he machine along ith the drive system is run at rated speed and drive motor input poer is noted. $hen speed is increased by %h! corresponding rpm over the ratedspeed and at the stage" the machine is tripped by opening the in/comer circuit breaker of drive system. $ime and speed are noted ith an interval of < seconds upto 9*

seconds" ith an interval of %* seconds upto %minute and so on till the machine comesto stand still.E;aluat#on o2 GD-

5>) is calculated as follos8$ime versus speed curve is plotted on a graph paper" taking @ a,is as time and ?/a,isas speed. ' tangent is dran at rated speed point on the curve" hich meets the timea,is at point $).$% is the point corresponding to rated speed.

5>) 19;


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+here" P Mechanical losses in k+ $F $ime in seconds 1$) /$%3 6 (ated rpm of the machine5>) of machine 5>) measured C 5>) of drive system 1knon3ROUTINE TESTS

$hese tests are carried out on each generator to ascertain that it is electrically andmechanically sound. $hese tests are carried out on different machines and areclassified as Stat#! te%t%

%. Measurement of insulation resistance of stator : rotor indings before andafter high voltage test 1machine at rest3.

). High 2oltage test on stator : rotor indings 1machine at rest3.9. Measurement of Polari!ation Inde, of stator inding.&. Measurement of d.c resistance of stator : rotor indings in cold condition.


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coefficient value of %.J and %.Q may be satisfactory" hile a value belo %.<indicates a damp machine.

/ $he inding is discharged to earth after each measurement. +ea%ure&ent o2 "olar#at#on #n/e> o2 %tator '#n/#n$he polari!ation inde, of stator inding" all the three phases together is measuredusing )


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/ $he high potential is given to copper and the core is earthed. $he outputvoltage of the high voltage tester is continuously increased to test the voltagelevel" held for % minute and subse#uently decreased to initial level.

/ 'fter the bottom bars are laid they are tested for % minute ith %.% 4P.Individual strips are of each bar are tested ith ))*2 ac for any possibleinter half shorts and inter bundle shorts.

/ 'fter the top bars are laid" High voltage testing is carried out ith %.% 4P for % minute and they are tested for inter half and inter bundle shorts. Inter half shorts test ith ))*2 ac is carried out after connecting the top and bottom bars ithout the connecting rings.

/ High voltage testing of the individual phases ith %.*< 4P is carried out for %minute after the completion of the inding . +hen one phase is under testthe other phases are earthed.

/ (esistances of individual phases are measured ./ >uring high voltage testing all the instrumentation cables assembled in the

machine are to be earthed./ Insulation resistance of each phase is to be measured after each high voltage

test./ +henever bunch bra!ing is employed for connecting top and bottom layers"

only inter half shorts test is to be carried out./

Rotor '#n/#n$he rotor inding must be tested at various stages of its manufacture and assembly.

/ $he output of the high voltage test e#uipment is connected to the output leador to the inding as the case may be and shaft is earthed. $he voltage iscontinuously increased to test voltage level" maintained for % minute andsubse#uently decreased to initial value.

/ $o test for inter turn shorts the re#uired voltage is applied across the totalinding of both the poles and voltage across the inding corresponding toeach pole is measured and recorded.

/ $he final test voltage 4P is ten times the rated voltage subected to ama,imum of 9.< k2 and manimum of %.< k2.

/ Before assembly of rotor bars H2 test is carried ith 4P )***2 for oneminute. $hen both the poles against earth are tested ith 4P %


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/ 'fter mounting the retaining ring high voltage testing of the inding againstthe shaft ith 4P&**2 is carried out for one minute.

/ 'fter over speeding and balancing at standstill H2 testing of the indingagainst the shaft ith 4P)**2 ac is carried out for one minute.

/ H2 testing of the inding is carried out at 9*** rpm ith iagram of H.2 $esting of Stator +inding +ea%ure&ent o2 D)C re%#%tan!e o2 Stator an/ Rotor '#n/#n% #n !ol/

!on/#t#onEu#"&ent

>igital micro ohmmeter and its measuring leads.a3 $hermometer 1Hg in glass3

>.- resistances of stator and rotor indings are measured separately usingdigital micro ohmmeter. $he instrument terminals are connected to the machineterminals and proper range in meter is selected. $he stabili!ed reading isrecorded.'mbient temperature from Hg in glass thermometer is recorded. $he stator resistance temperature detectors values are noted and average value of stator inding temperature is evaluated.

%.&.%. Evaluation of resistance at )*7-8/ Evaluation of resistances at )*7- 1( )*3 is done by using formula8/ ( )* ]( t 1)9


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a3


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. 2ibration monitor.k. (esistance temperature detectors monitor.l.


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$he e,citation is reduced and cut off. $he speed is reduced and the machine iscooled at loer speed. $he temperatures are checked from machine resistancetemperature detectors readings. $he machine is stopped hen it is sufficientlycooled don. 1$he stator inding temperatures to be less than ;*7-3.

rom the above data" the characteristic curves are plotted as follos8a3 N In versus If . b3 N In versus machine looses in k+.igure &.< Single line diagram for short circuit characteristics

+ea%ure&ent o2 &e!han#!al lo%%e%, o"en !#r!u#t !hara!ter#%t#! an/ lo%%e%$he machine is prepared for open circuit as shon in the figure &.;.

/ $he machine is run at rated speed and drive motor input voltage and currentare noted and m=c is e,cited gradually in steps" at )*N" &*N" ;*N" J*N"%**N and %)*N En 1En rated voltage of machine3.

't each step the folloing parameters are noted8 %3 Stator voltages 12ab"2bc"2ca3 )3 (otor current 1If 3 corresponding to stator voltage.

93 >rive motor voltage 12d3 and current 1Id3 corresponding to stator voltage. &3 (esistance temperature detectors readings at rated stator voltage 1%**N En3.


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E;aluat#on o2 #&"e/an!e4sing formula does evaluation of impedance8

G 2 =I ohms here G impedance in ohms 2 voltage in volts I current in amperes

Impedance measurement8/ 't rated rpm 1(otor inside stator3./ 't standstill 1(otor inside stator3./ 't standstill 1(otor outside stator3.igure &.Q Single line diagram for measurement of (otor impedance

EVALUATION OF EFFICIENCY

E22#!#en!$ o2 Turboenerator Intro/u!t#on

'mong some of the parameters" hich decide the #uality of the machine" like Shortcircuit ratio 1S.-.(.3" reactance : time constants" moment 7f inertia" efficiency"Efficiency of a machine is put under guarantee clause by most of the customers. 'nefficient machine adds in economy in performance and brings e,clusive respect to themanufacturer. Most of the manufacturers brand their product on efficiency. $hedemand is more inclined toards efficiency. Product efficient machine or loose themarket has become todayFs endeavor.Efficiency is defined as A$he ratio of output to input e,pressed in the same units"generally it is e,pressed as a percentage.$he output of the machine alays losses of the machine subtracted from the input.$hus NEfficiency %**]1output3 = 1output losses3^$he $otal loss consists of the folloing component lossesE>!#tat#on C#r!u#t Lo%%e%3

a. ield I)( loss8 $he I)( loss in the field inding.

b. Main rheostat loss8 $he loss in the rheostat in the main e,citing inding.c. Electrical loss in the brushes8 $he summation of I)( losses in the brushes and

the connectors and brush contact loss.d. E,citer loss8 'll the losses of e,citer mechanically driven from the main

shaft hich forms part of the complete unit and is used solely for e,citing themachine" together ith the losses in the rheostat in the field circuit of such ane,citer.

Lo%%e% #n/e"en/ent o2 Currenta. -ore loss8 -ore loss at no load" rated speed and rated terminal voltage. b. Bearing friction loss8 only losses in the bearing supplied ith the e#uipment

ill be included.

c. $otal indage loss8 $he total indage loss in the machine and e,citer" if any"including the poer absorbed in the fans forming an integral form of themachine.

d. Brush friction loss8 $he brush friction including that of the e,citer if mechanically driven.

D#re!t loa/ lo%%8 $he I)( loss in primary indings determined from the current andthe resistance of the inding. Stra$ loa/ lo%%3


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a3 Stray load loss determined from the primary indings determinedfrom the current in the conductors.

b3 Stray load loss in the conductors.

EVALUATION OF EFFICIENCY

'fter completion of routine tests" efficiency of the machine evaluated. $he folloing se#uence of calculation is folloed.%.7pen circuit characteristics is plotted on a graph paper from open circuitcharacteristics results by selecting @ C a,is as field current and ?/ a,is N of ratedvoltage. 2alues of field current at J*N"%**:"%%


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drop of %.* volt each polarity multiplied by the rated e,citation current. or brushless e,citation system" this loss is non/e,istent.

$o obtain field currents of the turbo generator at )


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7utput terminals of the machine under test are connected to the outlet bo,es of the test pit" hich in turn connects to the terminals in the control gallery here themeasurement is done. Eu#"&ent

/ >.-. motor drive system/ Bearing lubrication system/ >.-. voltmeters/ >.-. current shunts/ Phase se#uence meter / +ater load resistance bank/ -urrent $ransformers/ '.- 'mmeters/ '.-. voltmeters/ re#uency meter/ 2ibration probes and 2ibration monitor / Megger /


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indings are measured ith - resistance at )*deg ( t >- resistance of the inding at t deg $ $emperature of the inding in deg

Te%t Pro!e/ure o2 the "er&anent &anet enerator 8P+G9$he permanent magnet generator is assembled along ith the brushless e,citer on thegenerator rotor shaft. $he output is connected to a three/phase resistance load1variable in steps3. 's permanent magnet generator has got permanently magneti!edfield poles" it starts generating voltage right from the start of mechanical run.+ea%ure&ent O2 Out"ut Voltae At Rate/ S"ee/

$he machine is run up to rated speed and the output voltages 2uv" 2v" 2u are

measured. $o counter check" voltage is also measured at speeds of %=9" )=9" andrated speeds.

Che!#n O2 Pha%e Seuen!e an/ +ea%ure&ent o2 Freuen!$

+hen the machine is at %***rpm of the rated speed" the three phases input terminalsof the phase se#uence meter are simultaneously touched ith the output terminals if permanent magnet generator. $he se#uence indicated by the meter is recorded.'t rated speed" a fre#uency meter is connected across any to phases of the permanent magnet generator PM5 output terminals and fre#uency is measured.+ea%ure&ent O2 The Loa/ Chara!ter#%t#!

/ Machine is run at rated speed and loaded using three/phase resistance bank in steps up to rated load current.

/ 't each step" load currents and output voltages are noted./ Load magneti!ation curve is dran as phase/to/phase voltage versus load

current.+ea%ure&ent O2 #n%ulat#on re%#%tan!e ;alue an/ HV te%t%

/ Insulation resistance value of the stator inding is measured by


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and maintained for one minute and then reduced to !ero. +inding isdischarged and insulation resistance values are taken.

+ea%ure&ent O2 DC re%#%tan!e O2 Stator #n/#n'fter dynamic tests" the machine is alloed for cooling and hen it is sufficientlycooled" digital micro/ohmmeter measures the d.c resistances of all the three phaseindings separately. $he ambient temperature is also recorded and the evaluation of resistances at )*deg is done as shon in the figure.

NEEDED NOTESSynchronous Speed Ns =120 f/P

STATOR

Split casing of stator frame12PI generators3• -ore built ith lo loss cold rolled non/grain oriented sheet steel 1-(6573 ith

lo hysteresis : eddy current loss. .Stator packets separated by radial ducts

• -lamping of core by core tension bolts to eliminate core bulging

• -ore consolidation under heat : pressure

• 5luing of end packets to reduce end core vibration and loosening of ventilation pieces

• Stator insulation ith resin poor micalastic system

A%%e&bl$ o2 RTD% = F#re Dete!tor%• In stator inding" beteen bottom bar and top bar • In stator core• In hot and cold air chambers• In bearing shell• ire detectors mounted on both sides of the stator core to detect fire inside the

generator.SALIENT FEATURES OF DESIGNS OF BARS

• Roebel bar% '#th 51.. tran%"o%#t#on to re/u!e e//$ !urrent lo%%e% h#h

!a"a!#t$)

• Double la%% !o;ere/ !o""er !on/u!tor%)

• +ult# turn /e%#n 2or lo' !a"a!#t$ h#h ;oltae &a!h#ne%

• Re%#n r#!h !a 7 re%#n "oor VPI #n%ulat#on)

• Corona "rote!t#on o2 %tra#ht "art #n%ulat#on)Va!uu& Pre%%ure I&"renat#on

Preheat#n o2 the %tator 1.C, Durat#on 3 ( Hour Va!uu& Dr$#n at 1.C, .)- &bar Durat#on3 J(10(4 Hour%

Ent#re %tator a%%e&bl#e% are #&&er%e/ #nto l#u#/

ther&o%ett#n e"o>$ re%#n #n%ulat#on an/ ;a!uu&0"re%%ure #&"renate/)Re%#n Te&"3 1.DEG) C K70 -DEG) C, Re%#n F#ll J -. n

Re%#n Le;el3 (.. && Abo;e ob, Settl#n T#&e J (. n


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Pre%%ur#at#onN- Pre%%ure J : bar, Ra#%#n T#&e J 4. n

Hol/#n T#&e3 - Hour%)

Re%#n #% '#th/ra'n ba! A/;antae% o2 VPI

LONGER ELECTRICAL LIFE

HIGHER THER+AL CONDUCTIVITY

LESSER THICMNESS OF INSULATION HIGHER VOLTAGE STRESS)

S+ALL DISSIPATION FACTOR TIP0UP 8VOID FREE INSULATION 9

BETTER ELASTIC RESPONSE TO THER+O+ECHANICALSTRESSES

INSENSITIVITY TO HIGH TE+PERTURE AND TE+P) CHANGES8SUITABLE FOR GT APPLICATION9

LO INFLA+ABILITY

HIGHER RESISTANCE TO EFFECT +OISTURE

HIGHER CHE+ICAL RESISTANCE TO CORROSIVE GASES, LUBEOILS, ACIDS = ALMALIS

LESSER +ANUFACTURING CYCLE OF +7C)

HIGHER P7 RATIO) LOER COST OF +7C)

Rotor De%#n• Sol#/ rotor 2or#n o2 Cr N# +o V allo$ %teel

• S#l;er bear#n %e har/ ele!trol$t#! !o""er !on/u!tor 2or rotor '#n/#n

• Hal2 !o#l te!hnolo$ 2or rotor '#n/#n to a!h#e;e better 2orn an/

!on%ol#/at#on o2 en/ '#n/#n

• Slot 'e/e% o2 oo/ ele!tr#!al !on/u!t#;#t$ %horte/ at the en/ b$ reta#n#n

r#n%

• (4 +n (4 Cr reta#n#n r#n% o2 2ore/ non0&anet#! %teel %hrun 2#tte/ on therotor barrel

• - No%) o2 a>#al 2an% &ounte/ on ea!h %#/e o2 rotor 2or ;ent#lat#on o2

Generator '#th %!re'#n t$"e #n/#;#/ual 2an bla/e%

• - no%) o2 ournal bear#n% '#th #n%ulat#on to el#nate bear#n !urrent%


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• V#brat#on "#!u"% 2or ;#brat#on &on#tor#n

Te%t#nRout#ne Te%t%

W DC !ol/ re%#%tan!eW +e!h) run = ;#brat#on &ea%)W +ea%) Sha2t ;oltaeW +ea%) O2 rotor I&"e/an!eW IR te%t o2 %t = rt '#n/#n%W HV te%t o2 %t = Rt '#n/#n%W Pha%e Seuen!eW +ea%) O2 PI o2 %tator '#n/#nW +e!han#!al Balan!e

) O;er %"ee/ te%t 8(-.9

W Deternat#on o2 b$ %e"arat#on o2 lo%%e% &etho/W OC, SC te%t

T$"e Te%t%

W Te&"erature r#%e te%tW Su//en 5 SC te%tW Deternat#on o2 rea!tan!e = T#&e !on%t)W Voltae a;e2or&

BL E>!#ter De%#nB)L) E6CITERS

• NO BRUSHES

• A RECTIFIER HEEL CONVERTS THE AC OUTPUT OFTHE BLE

AR+ATURE TO DC)• THEY ARE EITHER COUPLED OR OVERHANG +OUNTED

CONSTRUCTIONAL FEATURESIT IS ALSO ANOTHER GENERATOR

• THE FIELD IS ON THE STATOR UNLIME THE TG)

• THE AR+ATURE IS ON THE ROTOR)

• ALL THE BRUSHLESS E6CITERS HAVE INBUILT7 SEPARATELY

+OUNTED P+G@S

TESTING OF GENERATOR

W +EASURE+ENT OF DC RESICSTANCE OF STATOR AND ROTORINDING

W INSULATION RESISTANCE OF STATOR INDINGW INSULATION RESISTANCE OF ROTOR INDINGW HIGH VOLTAGE TESTW PHASE SEUENCE TES

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TG Project Report

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