NTPC Training Report

ACKNOWLEDGEMENT

I

WOULD LIKE TO THANK SENIOR MANAGER

(HR

-

ED)

S

HRI

B.

R.

P

RASOON FOR HELPING ME IN COMPLETING THE

VOCATIONAL

TRAINING

IN

NTPC

L

IMITED

K

AHALGAON

.

S

ECONDARY

I

WOULD LIKE TO THANK

S

HRI

T.K.

J

HA

DGM

(EMD),

S

HRI

S.

K.

R

OHELA

DGM

(C

&

I),

S

HRI

R.

C.

J

HA

DGM

(O

PN

),

S

HRI

R.

S

RIVASTAVA

DGM

(MM)

FOR HELPING ME IN COMPLETING THE

VOCATIONAL TRAINING IN

NTPC

L

IMITED

KAHALGAON.

I

WOULD ALSO LIKE TO THANK MY PARENT AND THE ALMIGHTY FOR GIVING

ME MORAL STRENGTH

.

I

AM HIGHLY OBLIGED TO

S

HRI R

.

K

.

GUPTA

&

ALL

THE RESPECTED PERSONS WHO HAVE HELPED ME IN COMPLETING THE

VOCATIONAL TRAINING SUCCESSFULLY

.

PREFACE

T

RAINING IS DEFINED AS ANY ATTEMPT TO IMPROVE EMPLOYEE PERFORMANCE ON A

CURRENTLY HELD JOB OR ONE RELATED TO IT

.

T

HIS USUALLY MEANS CHANGES IN SPECIFIC

KNOWLEDGE

,

SKILLS

,

ATTITUDES

,

OR BEHAVIOUR

;

TO BE EFFECTIVE TRAINING SHOULD INVOLVE A

LEARNING EXPERIENCE

,

BE A PLANNED ORGANIZATIONAL ACTIVITY AND BE DESIGNED IN

RESPONSE TO IDENTIFIED NEED

.

I

DEALLY TRAINING ALSO SHOULD BE DESIGNED TO MEET THE

GOAL OF THE ORGANIZATION WHILE SIMULTANEOUSLY MEETING THE GOAL OF THE INDIVIDUAL

EMPLOYEES

KEY

WORD

PA

PRIMARY

AIR

IA

INDUCED

AIR

ID

FAN

INDUCED

FAN

PF

FAN

PRIMARY

FAN

FD

FAN

FORCED

DRAFT

FAN

D/A

DEAERATER

TG

TURBINE

SIDE

SG

BOILER

SIDE

K

SC

1K

G

/C

M2

HPT

HIGH

PRESSURE

TURBINE

IPT

INTERMEDIATE

PRESSURE

TURBINE

LPT

LOW

PRESSURE

TURBINE

BFP

BOILER

FEED

PUMP

TDBFP

TURBINE

DRIVEN

BOILER

FEED

PUMP

MDBFP

MOTER

DRIVEN

BOILER

PUMP

ESP

ELECTRO

STATIC

PRECIPITATER

GT

GENERATOR

ECN

ECONOMISER

RH

REHEATER

SH

SUPER

HEATER

SCAPH

STEAM

COIL

AIR

PREHEATER

UT

UNIT

TRANSFORMER

UAT

UNIT

AUXILIARY

TRANSFORMER

OAC

OPEN

APPROACH

CHANNEL

FST

FEED

STORAGE

TANK

FRS

FEED

REGULATING

STATION

FW

FEED

WATER

DMW

DEMINERALIZED

WATER

CFW

CLARIFIED

WATER

ECW

EQUIPMENT

COOLING

WATER

ACF

ACTIVATED

CARBON

FILTER

GSF

GRAVITY

SAND

FILTER

OHT

OVER

HEAT

TANK

INTRODUCTION

NTPC

LIMITED, THE LARGEST THERMAL POWER GENERATING COMPANY IN

INDIA, WAS

INCEPTED IN YEAR

1975. IT IS A PUBLIC SECTOR COMPANY WHOLLY OWNED BY

GOVERNMENT OF

INDIA

(GOI).

IN A SPAN OF

30 YEARS,

NTPC HAS EMERGED AS A MAJOR POWER COMPANY OF

INTERNATIONAL REPUTE AND STANDARD.

NTPC’S CORE BUSINESS INCLUDES ENGINEERING,

CONSTRUCTION AND OPERATION OF POWER GENERATING STATIONS AND PROVIDING CONSULTANCY

TO POWER UTILITIES AS WELL. PRESENTLY, THE TOTAL INSTALLED CAPACITY OF NTPC/JVS STANDS AT

MORE THAN

27904

MW, WHICH INCLUDES

18 COAL AND

8 GAS/NAPHTHA BASED POWER

STATIONS.

NTPC IS EXECUTING

KOL DAM

HYDRO

POWER

PROJECT

(

800

)

MW IN

HIMACHAL

PRADESH AND

TAPOBAN

VISHUNGAD

(520

MW) AND

LOHARINAG

PALA

(600

MW) HYDRO

PROJECTS IN UTTARAKHAND.

S

ALIENT

F

EATURES OF

K

H

STPP

●

LOCATION- KAHALGAON,DISTRICT BHAGALPUR

● NEAREST RAILWAY STAION- KAHALGAON

● NEAREST MAJOR TOWN- BHAGALPUR

● NEAREST AIRPORT- PATNA,KOLKATA

● NEAREST HIGHWAY- NH-80

● TOTAL LAND- 3360 ACRES

● LAND FOR PLANT- 833 ACRES

● LAND FOR TOWNSHIP- 432 ACRES

● LAND FOR MGR- 522 ACRES

● LAND FOR ASH DYKE- 1395 ACRES

● MAKE-UP WATER- 28 ACRES

● SYSTEM APPROACH ROAD- 70 ACRES

● OTHERS- 30 ACRES

● INSTALLED CAPACITY- 840 MW

● CONFIGURATION- STAGE-I 4*210 MW

STAGE-II 2*500 MW(PHASE-I)

1*500 MW(PHASE-II)

● FUEL- COAL

● SOURCE- RAJMAHAL HURRA,CHUPERBITA OF ECIL

● NEAREST WATER SOURCE- RIVER GANGES

● COOLING WATER SYSTEM- CLOSED CYCLE INDUCED DRAFT SYSTEM

● BENEFICIARY STATES- THE STATES AND UT’S OF NR,WR,ER,SR

● APPROVED PROJECT COST- RS 1715 CRORE(STAGE-I)

RS 6330 CRORE(STAGE-II)

K

AHALGAON

S

UPER

T

HERMAL

P

OWER

P

ROJECT

B

ACKGROUND

:

KAHALGAON SUPER THERMAL POWER PROJECT, STAGE II BEING SET UP BY NTPC IS

LOCATED NEAR KAHALGAON TOWN IN BHAGALPUR DISTRICT OF BIHAR STATE. THE STAGE II, OF THE

PROJECT SHALL COMPRISE OF THREE (3) UNITS OF 500 MW EACH. STAGE I OF THE PROJECT

COMPRISING OF FOUR (4) UNITS OF 210 MW EACH IS PRESENTLY UNDER COMMERCIAL OPERATION.

WITH THE ADDITION OF 3X500 MW UNITS UNDER STAGE II, THE ULTIMATE CAPACITY OF THE

PROJECT WILL BE 2340 MW (STAGE I, 4X210 MW+ STAGE II, 3X500 MW).

L

OCATION AND

A

PPROACH

:

THE PROPOSED EXPANSION STAGE II OF THE PROJECT IS LOCATED AT LATITUDE AND LONGITUDE

25



15 N AND 87



15 E RESPECTIVELY. THE NEAREST RAILHEAD COLGONG (KAHALGAON) RAILWAY

STATION OF EASTERN RAILWAYS IS APPROXIMATELY 2.0 KM AWAY FROM THE PROJECT SITE.

BHAGALPUR, THE NEAREST MAJOR TOWN, IS ABOUT 30 KM SOUTHWEST OF THE PROJECT SITE. THE

NEAREST COMMERCIAL AIRPORT IS PATNA AND LOCATED AT A DISTANCE OF 250 KM

APPROXIMATELY.

L

AND

R

EQUIREMENT

:

A TOTAL AREA OF 3360 ACRES OF LAND HAS BEEN ACQUIRED FOR THE PROJECT IN STAGE I AND

PROPOSED STAGE II OF THE PROJECT IS TO BE LOCATED WITHIN THE EXISTING AREA.

W

ATER

R

EQUIREMENT

:

THE PROJECT IS LOCATED NEAR RIVER GANGES. THE MAKE UP WATER REQUIREMENT FOR THE PLANT

IS PROPOSED TO BE DRAWN FROM RIVER GANGES. THE WATER REQUIREMENT FOR STAGE II OF THE

PROJECT SHALL BE OF THE ORDER OF 9000 CU.M/HR. THE BASIC REQUIREMENTS FOR RUNNING A

THERMAL POWER PLANT MAKE UP WATER FOR COOLING TOWER SYSTEM AND OTHER PLANT

REQUIREMENT AND A CONTINUOUS SUPPLY OF HIGH QUALITY COAL.

MAKE UP WATER FOR COOLING WATER SYSTEM AND OTHER PLANT REQUIREMENTS IS BEING DRAWN

FROM NTPC’S RAW WATER PUMP HOUSE LOCATED OVER AN INTAKE WELL IN RIVER GANGES. THE

INTAKE IS LOCATED ON RIGHT BANK OF THE RIVER WHICH IS ABOUT 3KM FROM THE PROJECT / PLANT

SITE. DURING COMMISSIONING OF STAGE – I (4 X 210 MW) OF THE PROJECT, DEEP CHANNEL OF

THE RIVER WAS HUGGING THE RIGHT BANK OF THE RIVER AND THE INTAKE WAS LOCATED CLOSE TO

THE DEEP CHANNEL OF THE RIVER.

SHOAL FORMATION HAS BEEN OBSERVED CLOSE TO THE INTAKE WELL LOCATION DURING LEAN

PERIOD, WHICH MAY BE BECAUSE OF THE CHANGE IN RIVER COURSE. TO ENSURE CONTINUOUS

SUPPLY OF MAKE UP WATER REQUIREMENTS FOR THE STATION AFTER COMMISSIONING OF STAGE – II

OF THE PROJECT, A SURVEY WAS CONDUCTED TO ASCERTAIN THE ADVERSE EFFECTS OF SHOAL

FORMATION AND HENCE, CARRY OUT SUCH REMEDIAL MEASURES WHICH WILL BRING BACK THE DEEP

CHANNEL OF THE RIVER CLOSE TO THE INTAKE.

TOPOGRAPHIC AND HYDROGRAPHIC SURVEY OF THE SAME WAS CARRIED OUT AS A PART OF

CONSULTANCY STUDIES DURING 6TH DECEMBER 2006 TO 10TH JANUARY 2007.

C

OAL

R

EQUIREMENT

:

COAL REQUIRED FOR RUNNING THE POWER PLANT IS PROCURED FROM LALMATIYA COALFIELD OF

JHARKHAND. THE REQUIREMENT IS ALSO MET FROM CHUPERBITA, RAJMAHAL EXPANSION AND

HURRA PROJECTS OF ECL.

K

AHALGAON

S

UPER

T

HERMAL

P

OWER

P

ROJECT

STAGE – II OF KAHALGAON SUPER THERMAL POWER PROJECT INCLUDES COMMISSIONING OF 3 UNITS

EACH OF 500 MW CAPACITIES. UNIT 7 IS ONE SUCH UNIT OF 500 MW. IT SPANS FROM 1954 (S) TO

2260 (S) AND 3625 (E) TO 3797 (E) ENCOMPASSING AN AREA OF ABOUT 52000 SQ.M. THE MAIN

AGENCY INVOLVED IN

MAIN

PLANT CIVIL WORKS IS

M/S

HSCL.

THE WORK STARTED ON

3RD

FEB

2004 AND WAS EXPECTED TO TAKE ABOUT

39 MONTHS.

BUT BECAUSE OF FEW PRACTICAL

DIFFICULTIES ENCOUNTERED DURING THIS TENURE, IT HAS CROSSED THE TIME LIMITS AND IS STILL

UNDER CONSTRUCTION.

THE ESTIMATED COST OF THE PROJECT IS 49.21 CRORE WHICH INCLUDES STRUCTURAL WORKS AND

CIVIL WORKS. ESTIMATE FOR STRUCTURAL WORKS IS 13 CRORE WHEREAS THE BALANCE BUDGET IS FOR

CIVIL WORKS WHICH INCLUDES PILING AND BALANCED CIVIL WORKS LIKE FOUNDATION AND FINISHES.

PILING ESTIMATE IS AROUND 13 CRORE AND THE REMAINING IS FOR THE BALANCED CIVIL WORKS.

THE ENTIRE AREA IS SUPPORTED ON

2320 PILES OF WHICH THERE ARE

1976 PILES OF

760 MM

DIAMETER AND 344 PILES OF 600 MM DIAMETER. THE PILE GOES TO A DEPTH OF 30 M.

THE MAIN PLANT CIVIL PACKAGE OF # 7 INCLUDES TWO WIDE AREAS, WHICH ARE

 TURBINE

GENERATOR

(T.G.)

AREA THAT INCLUDES

T.G. HALL, ALL FLOORS AT EACH

ELEVATION, AND TRANSFORMER YARD AREA.

 STEAM

GENERATOR

(S.G.)

AREA THAT INCLUDES BOILER, ELECTROSTATIC PRECIPITATOR

(ESP) AND ESP CONTROL ROOM BUILDING.

COAL

BASED

PLANT

COAL

TO

ELECTRICITY

COAL IS A FUEL THAT IS FOUND IN THE GROUND. IT IS MADE OF THE REMAINS OF PLANTS THAT DIED

MILLIONS OF YEARS AGO. SOIL PILED UP ON TOP OF THE REMAINS AND THAT WEIGHT COMPACTED IT

INTO A MORE DENSE MATERIAL, CALLED COAL. THE ENERGY IN THE COAL CAME FROM THE SUN AND

WAS STORED IN THE PLANTS. WHEN THE COAL IS BURNED, IT GIVES UP THAT ENERGY AS HEAT. THE

COAL'S HEAT ENERGY CAN THEN BE TURNED INTO ELECTRICAL ENERGY. THIS HAPPENS AT A POWER

PLANT.

• FIRST THE COAL IS MINED AND TAKEN TO A POWER PLANT.

• THEN THE COAL IS BURNED IN A BOILER WHICH CAUSES THE WATER IN THE BOILER PIPES TO

BECOME STEAM.

• THE STEAM TRAVELS THROUGH THE PIPES TO THE TURBINE.

• THE STEAM SPINS THE TURBINE BLADES.

• THE SPINNING BLADES TURN A SHAFT CONNECTED TO THE GENERATOR.

• IN THE GENERATOR, BIG MAGNETS SPIN CLOSE TO COILS OF WIRE.

• WHEN THIS HAPPENS, ELECTRICAL CURRENT IS PRODUCED IN THE WIRES.

• THEN THE ELECTRICITY GOES OUT THROUGH WIRES TO HOMES, SCHOOLS, AND BUSINESSES.

BOILER:

BOILER

IS

A

DEVICE

FOR

GENERATING

STEAM

FOR

POWER,

PROCESSING

OR

HEATING

PURPOSES.BOILER

IS

DESIGNED

TO

TRANSMIT

HEAT

FROM

AN

EXTERNAL

COMBUSTION

SOURCE

(USUALLY

FUEL

THE

HEAT

GENERATING

UNIT

INCLUDES

A

FURNACE

IN

WHICH

THE

FUEL

IS

BURNED

.WITH

THE

ADVANTAGE

OF

WATER

–COOLED

FURNACE

WALLS,

SUPERHEATERS,AIR

HEATERS

AND

ECONOMISERS,

THE

TERM

‘STEAM

GENERATOR’

WAS

EVOLVED

AS

A

BETTER

DESCRIPTION

OF

THE

APPARATUS.

BOILER

MAY

BE

CLASSIFIED

ON

THE

BASIS

OF

ANY

OF

THE

FOLLOWING

CHARACTERISTICS:

1. USE

2. PRESSURE

3. MATERIALS

4. SIZE

5. TUBE

CONTENT

6. TUBE

SHAPE

AND

POSITION

7. FIRING

8. HEAT

SOURCE

9. FUEL

10. FLUID

11. CIRCULATIONS

12. FURNACE

POSITION

13. FURNACE

TYPE

14. GENERAL

SHAPE

15. TRADE

NAME

16. SPECIAL

FEATURES

CATEGORIES

OF

BOILERS:

BOILERS

ARE

GENERALLY

CATEGORISED

AS

FOLLOWS

:

1) STEEL

BOILERS

2) FIRE

TUBE

TYPE

3) WATER

TUBE

TYPE

4) HORIZONTAL

STRAIGHT

TUBE

5) BENT

TUBE

6) NATURAL

CIRCULATION

7) POSITIVE

CIRCULATION

8) SHELL

TYPE

9) CAST

IRON

BOILERS

10) SPECIAL

DESIGN

BOILERS

ARRANGEMENT

OF

MAIN

PARTS

OF

BOILER

:

THESE

ACCESSORIES

INCLUDE

–

1) ECONOMISER

2) BOILER

DRUM

3) DOWN

COMERS

4) WATER

WALLS

5) WATER

WALL

PLATEN(USED

FOR

PRESSURE

BOILERS)

6) PRIMARY

SUPER

HEATER

7) PLATEN

SUPER

HEATER

8) FINAL

SUPER

HEATER

9) REHEATER

10) BURNER

11) IGNITORS

ARRANGEMENT

OF

BOILER:

#FURNACE

(

A

)

T

YPE

:

F

USION

W

ELDED

(

B

)

W

IDTH

:

14.46M

TRS

.

(

C

)

B

READTH

:

11.85M

TRS

.

(

D

)

V

OLUME

:

7664

M

3

(

E

)

F

URNACE

E

XPLOSION

/

I

MPLOSION

P

RESSURE

:

±

660

MM

W

CL

.

(

F

)

F

URNACE

S

URFACE

:

2712

M

2

ABOILERFURNACEISTHATSPACEUNDERORADJACENTTOABOILERINWHICHFUELISBURNEDANDFROMWHICH THE COMBUSTION PRODUCTS PASS INTO THE BOILER PROPERLY. IT PROVIDES A CHAMBER IN WHICH THE COMBUSTIONREACTION CAN BE ISOLATEDANDCONFINEDSO THAT THEREACTIONREMAINS ACONTROLLED FORCE.INADDITIONITPROVIDESSUPPORTORENCLOSUREFORTHEFIRINGEQUIPMENT.

THEFURNACEMUSTPROVIDETHEFOLLOWING–

>>PROPERINSTALLATION,OPERATIONANDMAINTENANCEOFFUELBURNING EQUIPMENT.

>>SUFFICIENTVOLUMEFORCOMBUSTIONREQUIREMENTS. >>ADEQUATEREFRACTORIESANDINSULATION.

#BOILER

DRUM

:

THEFUNCTIONOFSTEAMDRUMISTOSEPARATETHEWATERFROMTHESTEAMGENERATEDIN THEFURNACE WALLS ANDTOREDUCETHEDISSOLVEDSOLIDCONTENTSOFTHESTEAMTOBELOWTHEPRESCRIBEDLIMITOF

#ECONOMISER

:

THE PURPOSE OFECONOMISERISTOPREHEATTHE BOILERFEEDWATERBEFOREITISINTRODUCEDINTOTHE STEAMDRUMBYRECOVERINGHEATFROMTHEFLUEGASESLEAVINGTHEBOILER.THEECONOMISERISLOCATEDIN THE BOILERREAR GAS PASS BELOW THE REAR HORIZONTAL SUPERHEATER.THE ECONOMISER IS CONTINUOUS UNFINNEDLOOPTYPEANDWATERFLOWSINUPWARDDIRECTIONANDGASINTHEDOWNWARDDIRECTION.

#SUPERHEATER

:

THERE ARE THREE STAGES OFSUPERHEATERBESIDES THESIDE WALLS ANDEXTENDED SIDEWALLS.THEFIRST STAGECONSISTSOFHORIZONTALSUPERHEATEROFCONVECTIONMIXEDFLOWTYPEWITHUPPERANDLOWER BANKSLOCATEDABOVEECONOMISERASSEMBLYINTHEREAR PASS.THEUPPERBANKTERMINATESINTOHANGER TUBES,WHICH ARE CONNECTED TO OUTLET HEADER OF THE FIRST STAGE SUPERHEATER.THE SECOND STAGE SUPERHEATERCONSISTS OF PENDANTPLATEN WHICH ISOFRADIANT PARALLEL FLOW TYPE.THE THIRDSTAGE SUPERHEATERCONSISTS OF PENDANTPLATEN WHICH ISOFRADIANT PARALLEL FLOW TYPE.THE THIRDSTAGE SUPERHEATERPENDANTSPACEDISOFCONVECTIONPARALLELFLOWTYPE.

THEOUTLETTEMPERATUREANDPRESSUREOFTHESTEAMCOMINGOUTFROMTHESUPERHEATERIS540DEGREE CELSIUSAND157KG/CM^2RESPECTIVELYFORH.P.UNITS

#REHEATER

:

THEFUNCTIONOFREHEATERISTOREHEATTHESTEAMCOMINGOUTFROMTHEHIGHPRESSURETURBINETOA TEMPERATUREOF540DEGREECELSIUS.

THEREHEATERISCOMPOSEDOFTWOSECTIONS.THEFRONTPENDANTSECTIONANDREARPENDANTSECTION. THEREAR PENDANTSECTION ISLOCATEDABOVETHEFURNACE ARCANDTHEREAR WATERWALL ANDFRONT PENDANT SECTION IS LOCATED BETWEEN THE REAR WATER HANGER TUBES AND THE SUPERHEATER PLATEN SECTION

#BURNERS

:

THEREARETOTALTWENTYFOURPULVERISEDCOALBURNERSFORCORNERFIREDC.E.TYPEBOILERSANDTWELVE OILBURNERSPROVIDEDEACHINBETWEENTWOPULVERISEDFUELBURNER.THEPULVERISEDCOALBURNERSARE

ARRANGEDINSUCHAWAYTHATSIXMILLSSUPPLYTHECOALTHEBURNERSAT4CORNERS,OFTHEFURNACE.ALL THENOZZLESOFTHEBURNERSAREINTERLINKEDANDCANBETILTEDASASINGLEUNITFROM+30TO-30DEGREE. THEOILBURNERAREFEDWITHHEAVYFUELOILTILLLOADREACHESTOABOUT25%.

#IGNITERS

:

THERE ARE TWELVESIDE EDDY PLATE OIL/H.E.A.IGNITERS PER BOILER. THE ATOMISING AIRFOR IGNITORSARETAKENFROMPLANTAIRCOMPRESSERSAT7KG/CM^2(GAUGE).

THE BURNER ARE LOCATED AT THE THREE ELEVATIONS. EACH ELEVATION HAS FOUR OPIL BURNERS AND IGNITORS.THESE ELEVATIONS ARE NORMALLY KNOWN AS AB ELEVATION,CD ELEVATION AND EF ELEVATION.MAINLYTWOTYPESOFIGNITORSAREUSED:

>>EDDYPLATEIGNITOR

>>HIGHENERGYARCTYPEIGNITORS

BOILER DESIGN & FIELD DATA :

 RATING :MS690T/HR,140KG/CM2,5400C,

RH569T/HR,27.6KG/CM2,,3280C/5400C.

 FEED WATER TEMPERATURE : 248°C

 BOILER DRUM PRESSURE : 161KGF/CM2

 OVERALL DIMENSION :WIDTH (ALONG COLUMN AXIS)29.46M, :DEPTH (ALONG COLUMN AXIS)42.01M,

:HEIGHT (ELEVATION OF CENTER LINE)68.9M.

 MASS OF PR.PARTS :1954 TONS.

 MASS OF BOILER METAL :7250 TONS.

 GUARANTEED BOILER EFFICIENCY AT AIR TEMP 300C

=89%.(AT NET COMBUSTIBLE BASIS)

=87.15%.(AT GROSS CALORIFIC VALUE BASIS)

 DESIGN EFFICIENCY OF BOILER (APPROX.):91.64% LOSSES :IN FLUE GAS 5.97%,

:NON COMBUSTIBLE 2%(CHEMICALS 0.15%, MECH.BALANCE),

:INTO ASHES 0.09%.

 EXIT FLUE GAS TEMP.:1370C,(WITH WORST COAL 1420C).

 FLUE GAS TEMP AT FURNACE OUTLET :APPROX.11200C,

 TEMP. OF HOT AIR :3880C,(WITH WORST COAL 3910C)

 LOAD WITHOUT FURNACE OIL :WITH GUARANTEED FUEL :70 TO 100%,

:WITH LOW GRADE FUEL :85 TO 100%,

:WITH HIGH GRADE FUEL :55 TO 100%.

 BOILER LOAD WITH ALL 12 OIL BURNERS (APPROX.):30% OF NOMINAL LOAD

 TOTAL COAL FIRING RATE : 126.4 TO191T/ HR

GENERATOR

T

URBO GENERATOR HAS

3

CIRCUITS

,

A

)

MAGNETIC CIRCUIT

,

B

)

E

LECTRIC CIRCUIT AND C

)

M

ECHANICAL SUPPORTS AND AUXILIARIES

.

T

URBO GENERATORS

:

S

TEAM TURBINES RUN EFFICIENTLY ONLY AT HIGH SPEEDS

,

SO THAT

2-

POLE GENERATOR IS COMMON EVEN AT HIGH RATINGS

.

T

HE ELECTRIC AND MAGNETIC LOADING IS EXCEPTIONALLY HIGH

.

T

HE ROTOR DIAMETER IS LIMITED TO

1.2

M

.

T

HE ACTIVE CORE LENGTH MUST BE OF THE ORDER OF

10

MM PER

MVA.

T

HUS THE LENGTH OF A

500MW

GENERATOR MAY BE

5

M AND SHAFT LENGTH MAY BE

12

M

.

S

TATOR CORE DIAMETER

3

M AND CASING

4

M

.

T

HE STATOR WINDINGS ARE DOUBLE LAYER FORM SO THAT HARMONICS CAN BE REDUCED BY CHORDING

.

F

OR LARGE GENERATORS THE STATOR MMF MAY REACH UP TO

300KA-

T PER POLE AND TO AVOID EXCESSIVE DEMAGNETISATION EFFECT THE ROTOR MMF MUST BE OF COMPARABLE MAGNITUDE AS DEFINED BY THE SHORT CIRCUIT RATIO

.

A

S IT IS UNDESIRABLE TO HAVE HIGH TOOTH SATURATION

,

LONG AIR GAP IS NECESSARY

-5

MM FOR

1MVA

MACHINE TO

100

MM FOR

500MVA

MACHINE

.

R

OTOR

:

T

HE

I

2

R

LOSS PER UNIT MASS OF CONDUCTOR MATERIAL IS OF THE ORDER OF

150W/

KG IN STATOR AND

500W/

KG IN THE ROTOR

.

T

HEREFORE THE ROTOR IS THE LIMITING MEMBER

.

T

HE DIAMETER IS LIMITED BY THE

CONSIDERATIONS OF CENTRIFUGAL FORCE

,

DEFLECTION AND CRITICAL SPEED

.

A

N EXCITATION HAS TO BE PROVIDED IN ACCORDANCE WITH THE STATOR ELECTRIC LOADING AND SHORT CIRCUIT RATIO

.

T

HE EXCITATION WINDING MUST BE CONTAINED IN THE SLOTS OF SUCH WIDTH SO AS TO LEAVE TEETH ADEQUATE TENSILE STRENGTH AND BENDING STRENGTH AND TO CARRY MAGNETIC FLUX WITHOUT EXCESSIVE SATURATION

.

R

OTOR

:

CYLINDRICAL TYPE

,

SHAFT AND BODY FORGED IN ONE PIECE FROM

N

ICKEL

-

CHROMIUM

-

V

ANADIUM

-MOLYBDENUM STEEL HAVING ULTIMATE STRENGTH UP TO

800N/

M2

.

S

LOTS ARE MILLED OUT AXIALLY

.

D

YNAMICALLY BALANCED WITH HIGH DEGREE OF ACCURACY UP TO

20%

OVER SPEED FOR

2

MINUTES

.

C

RITICAL SPEED IS AT

1200

RPM

(1370

RPM

)

AND

2.7

AND

3.0

TIMES THIS SPEED

.



W

INDING

:

HARD DRAWN SILVER BEARING COPPER

,

I

NSULATION

:

EPOXY GLASS

,

NONMAGNETIC STEEL RETAINING RING FOR OVERHANG

.



F

ANS

:

PROPELLER TYPE

,

SHAFT MOUNTED ON EITHER SIDES



S

LIP RINGS

:



F

ILED LEAD

:

SLIP RINGS TO WINDINGS VIA SEMI FLEXIBLE COPPER LEADS

.

S

TATOR

:

COLD ROLLED GRAIN ORIENTED SILICON STEEL

,

MECHANICALLY STRONG TO WITHSTAND INTERNAL PRESSURE OF EXPLOSION OF HYDROGEN AND AIR MIXTURE

.

M

ECHANICAL PROBLEMS ARISE BECAUSE OF THE DOUBLE FREQUENCY VIBRATIONS SET UP BY THE ROTATION OF THE AXIS OF THE MAGNETIC FIELD AND FROM INTERNAL PRESSURE OF THE HYDROGEN COOLANT

.

C

ORE VIBRATION IS PREVENTED FROM BEING TRANSMITTED TO THE CASING BY A FORM OF FLEXIBLE MOUNTING

.

W

INDING

:

3

PHASE

,

DOUBLE LAYER

,

SHORT CHORDED

,

SINGLE TURN

,

TWO PARALLEL WINDING

(

DOUBLE STAR

).

E

ACH CONDUCTOR IS ELABORATELY SUBDIVIDED TO LIMIT EDDY CURRENT LOSS

.

T

HE INSULATION MAY BE MICA PAPER AND ASBESTOS OR GLASS FIBRE TAPE WITH POLYESTER OR EPOXY BONDING TO GIVE MECHANICAL STRENGTH

.

ELECTROMAGNETIC FORCES

,

H

ARD WOOD BLOCKS WITH GLASS FIBRE CORD OR TAPE MAY BE USED

,

WITH METALLIC

(

NON

-

MAGNETIC

)

BRACKETS AS ANCHORAGE

.

E

DDY

C

URRENTS

:

T

HE PARASITIC EDDY CURRENTS IN AN ISOLATED CONDUCTOR DUE TO ITS OWN FIELD ARE CALLED THE SKIN EFFECT

.

T

HEY ARISE ON ACCOUNT OF THE INDUCTANCE OF THE CENTRAL PART OF THE CONDUCTOR EXCEEDS THAT OF THE OUTER PARTS

.

T

HEREFORE THE CURRENTS ARE CONFINED TO THE PERIPHERY

.

T

HE GREATER INDUCED EMF OF SELF INDUCTION IN THE MIDDLE PARTS OF THE CONDUCTOR CAUSES CIRCULATING CURRENTS WHICH

,

SUPERIMPOSED ON THE MAIN CURRENT INCREASES THE

I

2

R

LOSS

.

T

HE EFFECTS OF ALTERNATING LEAKAGE FIELDS ARE INTENSIFIED BY THE PROXIMITY OF FERROMAGNETIC MATERIAL

.

S

LOT CONDUCTORS

:

T

HE FIRST ORDER EDDY CURRENT DISTURB THE ORIGINALLY UNIFORM CURRENT DENSITY

,

SUPERIMPOSING A SECOND ORDER MMF

,

FLUX

,

EMF AND EDDY CURRENTS WHICH IN TURN DEVELOP THIRD ORDER COMPONENT AND SO ON

.

N

OT ONLY DOES EDDY CURRENT THE

I

2

R

LOSS

,

BUT ALSO DISTURB THE FIELD DISTRIBUTION

.

T

HE LARGE CURRENTS IN STATOR PRODUCE HIGH PULSATIONAL FORCES BETWEEN CONDUCTORS

,

REACHING UP TO

80

K

N/

M IN

500MW

MACHINES

.



D

ISTILLATE HEADER

:

R

ING TYPE WATER HEADER OF COPPER INLET AND OUT LET HEADERS

–

TURBINE SIDE

.



T

ERMINAL BUSHINGS

:

WATER

-

COOLED

;

THEY ARE HOUSED IN A CHAMBER MADE OF NONMAGNETIC STEEL

PLATES

.

A

IR GAP

:

T

URBO GENERATORS HAVE LARGE RADIAL GAPS FOR REASONS OF OPERATIONAL STABILITY

.

I

N CONVENTIONAL TOOTHED STATOR

,

THE SLOTTING CONCENTRATES THE FLUX INTO THE TEETH

,

SATURATION AND CORE LOSS LEVELS ARE HIGH AND POLE FACE LOSSES OCCUR

.

T

HE DEEP SLOTS MAKE CONDUCTOR TRANSPOSITION ESSENTIAL AND INTRODUCE SOME DIFFICULTIES IN DIRECT WATER

-

COOLING

.

T

HE HIGH VOLTAGE INSULATION IN WINDINGS RESULTS IN LOW SPACE FACTOR AND END WINDINGS BULKY AND NEEDS ELABORATE SUPPORT

.

L

ARGE TURBO GENERATORS

:

T

HE SPEED IS FIXED BY THE FREQUENCY

.

T

HE DIMENSIONS ARE FIXED BY THE ROTOR DIAMETER

(D)

AND THE ACTIVE CORE LENGTH

(

L

).

T

HE LIMIT OF

D

IS SET BY THE CENTRIFUGAL FORCES WHILE THOSE OF L CONCERNS THE RIGIDITY OF THE ROTOR

.

T

HE PRESENT LIMIT OF

D

FOR

50H

Z IS

1.2

M

,

AND LENGTHENING OF ROTOR BEYOND L

=5D,

GIVES NO IMPROVEMENT

.

B

UT A SMALL IMPROVEMENT OF

D

WILL GIVES SUBSTANTIAL RISE IN CAPABILITY

.

F

OR ROTATIONAL SPEED N

,

THE ROTATIONAL STRESS IS PROPORTIONAL TO

D

2N2

.

T

HE

D

L PRODUCT AFFECTS THE CRITICAL SPEED

.

F

OR LARGE MACHINES COMPLEX CALCULATIONS ARE REQUIRED

,

TAKING INTO ACCOUNT DIFFERING RIGIDITIES OF THE DIRECT AND QUADRATURE AXES OF ROTOR

,

EFFECTS OF BEARING DEFORMATION AND CHARACTERISTICS OF THE GENERATOR

-

TURBINE COUPLING

.

V

IBRATION PROBLEMS CAN BE COMPLEX

.

A

2-

POLE STATOR IS DEFORMED INTO AN ELLIPSE BY INTENSE MAGNETIC ATTRACTION

;

WITH MINOR AXIS DIRECTED ALONG THE AXIS OF THE AIR GAP FLUX

,

AS THE ROTOR ROTATES SO DOES THE DEFORMATION

.

T

HIS INITIATES A STRONG VIBRATION AT TWICE THE ROTATIONAL SPEED

.

V

IBRATION AFFECTS THE WINDING BOTH IN THE SLOTS AND IN THE OVERHANG

.

T

HE HEAT TRANSFER CAPACITY OF WATER IS

50

TIMES THAT OF AIR

,

BUT ITS DENSITY IS

1000

TIMES GREATER

.

G

AS COOLERS

:

M

ADE OF ADMIRALITY BRASS TUBES

.

E

ND COVER OF WATER CHAMBERS CAN BE REMOVED WITHOUT PURGING HYDROGEN FROM GENERATOR

.

B

RUSH GEAR

:

B

RUSHES IN THE UPPER

2/3

RD PERIPHERY

,

BRUSHES CAN BE CHANGED DURING NORMAL RUNNING

.

S

HAFT SEALS

:

TO PREVENT ESCAPE OF HYDROGEN

.

E

XCITATION SYSTEM

:

W

HY NOT DC EXCITERS

?



L

ARGE NUMBERS OF BRUSHES

,

EXTENSIVE COMMUTERS AND BRUSH GEAR MAINTENANCE

.



D

URING CHANGE OF LOAD CHANCES OF FLASH OVER

.



F

OR RELIABILITY EXCITERS ARE DIRECTLY COUPLED

,

THIS MEANS REDUCTION IN GEARS THAT ARE NECESSARY

.



A

T HIGHER SPEEDS INVARIABLY COMMUTATION PROBLEMS

.

AVR:

S

TATIC EXCITATION SYSTEM

,

A

UTOMATIC AND SEPARATE VOLTAGE REGULATORS



M

AXIMUM AND

M

INIMUM EXCITATION LIMITERS



C

HANGE OVER TO

M

ANUAL CONTROL IN CASE OF FAULT IN

A

UTO MODE

.

G

ENERATOR OPERATIONAL LIMITS

:



T

ERMINAL VOLTAGE

-

±

5%

(

AT RATED POWER AND PF

)



S

TATOR CURRENT

-

±

5%

(

AT RATED POWER AND PF

)



V

OLTAGE

-

±

10%



C

URRENT

-

+105%



F

REQUENCY

-

±

5

(

DUE TO TURBINE LIMITATIONS

,

+2%

AND

–3%)

1) L

ESSER DENSITY

,

LESSER WINDAGE LOSS



1/14

TH THE AIR DENSITY



ADVANTAGE IS LIMITED TO

1/10

TH



U

SE OF HYDROGEN INCREASES THE EFFICIENCY BY

½

TO

1%

2) R

EDUCTION IN SIZE OF THE MACHINE



T

HERMAL CONDUCTIVITY IS

7

TIMES THAT OF AIR

.



H

EAT TRANSFER IS

1.5

TIMES

.



A

T

0.5

PSI

–

RATING IS INCREASED BY

20-25%



A

T

30

PSI

–

RATING IS INCREASED BY

35%

3) I

NCREASED LIFE OF THE MACHINE



E

NCLOSED CONSTRUCTION KEEP THE DIRT AND MOISTURE OUT

.



N

O DETERIORATION OF ARMATURE INSULATION

.

T

HAT IS DURING CORONA

,

OZONE

,

NITRIC ACID ARE FORMED WHICH ATTACKS THE INSULATION

.

4) I

NCREASE IN OUT PUT FROM THE SAME MACHINE



E

VERY

0.07

AT

.

P

RESSURE INCREASE UP TO

1

AT

.

I

NCREASE THE MACHINE OUT PUT BY

1%.



E

VERY

0.07

AT

.

P

RESSURE INCREASE FROM

1

AT

.

TO

2

AT

.

I

NCREASE THE MACHINE OUT PUT BY

0.5%.



I

NCREASE IN HYDROGEN PRESSURE ENHANCES THE WIND AGE LOSSES

.

D

ISADVANTAGES

:

F

ORMS EXPLOSIVE MIXTURE WITH AIR BETWEEN

5

/

95%

TO

75

/

25%.



C

OMPLICATED CONTROL AND GAS TIGHT SEAL SYSTEM

.



E

XPLOSION PROOF CONSTRUCTION

–

INCREASED COST

.



P

URGING OUT FACILITY WITH

CO

2

.

A

S DIAMETER OF MACHINE CANNOT BE INCREASED

,

FOR CAPACITY

,

CONDUCTOR LENGTH HAS TO BE INCREASED

.

–

C

OOLING WITH GAS WITH GAS BECOMES DIFFICULT

.

T

ECHNICAL

D

ATA OF

G

ENERATOR OF

K

AHALGAON

T

YPE

TBB-220-2ET3

P

OWER

247.059MVA,

210MW

R

ATED VOLTAGE

15.75KV

R

ATED CURRENT

9056A,

P

OWER FACTOR

0.85

PF

,

S

PEED

3000

RPM

,

50H

Z

C

ONNECTION

D

OUBLE STAR

I

NSULATION CLASS

C

LASS

F

C

ONDUCTOR

/

SLOT

2

T

URNS

/

PHASE

10

T

ERMINALS

/

PHASE

3

N

O

.

OF SLOTS

60

N

O

.

OF TERMINALS

9

E

FFECTIVE CORE LENGTH

(

L

)

4.06

M

T

OTAL LENGTH OF STATOR

L

ENGTH OF TURN

13.95

M

F

LY WHEEL EFFECT

5.6

T

.

M2

C

RITICAL SPEED

1370,

3400

M

AX

.

T

ORQUE AT

SC

IN STATOR

8

FOLD

G

AS VOLUME

56

M3

(

WITH ROTOR

),

60

M3

(

WITHOUT ROTOR

)

C

APACITANCE

S

TATOR

–0.69

MICRO

F,

M

AX

.

TEMP

.

S

TATOR WINDING

–75



C,

S

TATOR CORE

–105



C

DC

RESISTANCE

1.6

MILLI



R

EACTANCE

X

D

X’

D

X’’

D

X

2

X

206%

26%

17.5%

21.3%

1

0

.

3

%

T

ESTED

HI

VOLTAGE

49KV

PEAK

-

TO

-

PEAK

,

34.5KV

RMS

.

O/L

CAPACITY OF

S

TATOR

1.1

1.15

1.2

1.3

PU

30

15

3

1

MIN

.

N

EG

.

S

EQ

.

O/L

CAPACITY

0.25

0.50

1.0

2.0

PU

128

32

8

2.0

SEC

.

M

OTORING MODE

S

TEAM LESS CONDITION IS OF NO DIRECT HAZARD TO GENERATOR

.

B

ECAUSE CONDITIONS OF

T

URBINE IT IS NOT OPERATED FOR MORE THAN

3

MIN

.

IN STEAM LESS CONDITION

M

ANOEUVRING

330

STARTS AND STOPS PER YEAR

.

R

ATE OF LOAD PICK UP



6

%

PER MIN

.

R

ATE OF

R

EACTIVE LOAD PICK UP



6%

PER MIN

.

R

OTOR

2330A,

303V,

CLASS

F

N

O

.

OF TURNS

9

D

AMPER WINDING

(4

INNER

+

4

OUTER

)

DAMPER SEGMENTS

T

ESTED

HI

VOLTAGE

3.33KV

FOR

1

MIN

.

C

APACITANCE

0.29

MICRO

F,

M

AX

.

TEMP

.

R

OTOR WINDING

-115



C

I

MPEDANCE

4.54



AT

230V,

AT

50H

Z

O

VER SPEED TEST

3600

RPM FOR

2

MIN

.

E

XCITATION LOSS

818

K

W

C

OPPER LOSS

964

K

W

M

ECHANICAL LOSS

730

K

W

N

O LOAD LOSS

380

K

W

L

OSS OF FIELD

G

EN

.

CAN RUN WITH OUT FIELD FOR A MAX

.

15

MIN

.

AT

40%

THE RATED LOAD

.

I

N CASE OF LOSS FIELD

,

REDUCE THE LOAD TO

60%

WITHIN

30

SEC

.

AND TO

40%

LOAD IN

1.5

MIN

.

R

OTOR EARTH FAULT

-

FIRST

₅

_K



O/L

CAPACITY OF ROTOR

1.1

1.2

1.5

2.0

P

U

3600

240

60

20

S E C

.

G

ENERATOR

SCC

I

F

,

A

193

570

985

1390

1760

S

TATOR

,

A

975

2980

5080

7160

9020

G

ENERATOR

OCC

S

TATOR

V

OLTAGE

,

K

V

5.12

5.8

7.87

10.0

11.8

15.75

17.1

I

F

,

A

237

267

362

464

560

800

920

M

AX

.

C

ONTINUOUS

L

OAD

214.5

MW,

AT

0.85

PF

,

AND COOLING WATER TEMPERATURE OF

36



C

AT GAS COOLER OUT LET

P

ERMITTED VOLTAGE VARIATION FOR WHICH THE MAXIMUM CONTINUOUS POWER IS RETAINED

±5%

OF THE RATED

,

I

.

E

.

14.96

K

V

TO

16.53

K

V

M

AX

.

VOLTAGE PERMITTED

110%

OF RATED

,

I

.

E

.

17.32

K

V

V

ARIATION OF

G

ENERATOR POWER WITH RESPECT TO VARIATION OF VOLTAGE

V

OLTAGE IN K

V

17.32

17.16

17.01

16.85

16.69

16.53

15.75

14.96 14.17

P

OWER IN

MW

188.7

195.2

200.5

207.0

210.2

214.5

214.5

214.5 202.7

S

TATOR CURRENT IN K

A

7248

7565

7836

8154

8380

8607

9060

9513

9513

V

OLTAGE

,

%

OF RATED VALUE

110

109

108

107

106

105

100

95

90

P

OWER

,

%

OF RATED VALUE

88

91

93.5

96.5

98

100

100

100

94.5

S

TATOR CURRENT

,

%

OF RATED

80

83.5

86.5

90

92.5

95

100

105

105

BRIEF DESCRIPTION OF 6.6KV HT.SW.GR OF MAINPLANT SCHEME

6.6KV

SWITCHER OF

K

AHALGAON IS DESIGNED AND SUPPLIED BY

R

USSIA

.

E

ACH

U

NIT CONSISTS OF

T

WO

6.6KV

BUSHES

,

N

AMED AS

BA

&

BB.

E

VERY BUS IS CHARGED BY TWO SOURCES

,

NAMELY STATION OR

R

ESERVE

I

NCOMER AND

UAT

OR WORKING

I

NCOMER

.

T

HESE

I

NCOMER ARE CHARGED BY TWO TRANSFORMERS

,

I

.

E

.

63

MVA

S

TATION

T

RANSFORMER

(ST)

&

40

MVA

U

NIT

A

UXILIARY

T

RANSFORMER

(UAT).

T

HE

ST

IS CHARGED FROM

S

WITCH

Y

ARD

132

KV

BUS AND

UAT

IS CHARGED FROM ITS

U

NIT

G

ENERATOR AT

15.75KV.

T

HESE TRANSFORMERS ARE HAVING DOUBLE SECONDARY WINDINGS OF

6.6KV.

G

ENERALLY

,

THE BUSES ARE LOADED ON

UAT,

WHEN THE UNITS ARE IN RUNNING CONDITION

.

W

HEN UNIT TRIPS

,

S

TATION COMES INTO SERVICE BY

AUTO-CHANGE

OVER

SCHEME

(ACO).

T

HE

ACO

SCHEME OPERATES FOLLOWING CONDITION

:

1. W

HEN

G

ROUP

-

I

PROTECTION OF

U

NIT OPERATES

,

2. W

HEN

G

ROUP

-

II

PROTECTION OF

U

NIT OPERATES

,

3. U

NDER VOLTAGE IN THE BUS

,

&

4. M

ECHANICAL

P

ROBLEM IN

UAT

BREAKER

.

A

PART FROM ABOVE

,

CHANGEOVER CAN ALSO BE DONE MANUALLY FROM

UCB.

T

HE ABOVE

ACO

IS ONLY FOR CHANGE OVER FROM

UAT

I

NCOMER TO

S

TATION

I

NCOMER

.

SWITCH-GEAR

S

WITCH GEAR IS A CONTROL SWITCH THAT

C

ONTROL THE OPERATION OF A POWER CIRCUIT

.

T

HE TWO FUNCTION OF A SWITCH IN POWER SYSTEMS ARE

–

I).

T

O PERMIT THE TRANSMISSION LINES TO BE CONVENIENT PUT INTO AND TAKEN OUT FROM SERVICE

.

I

I

).

T

O DISABLE THE SOME PLANT AND LINES WHEN THESE BECOME FAULTY

,

TO BE RAPIDLY AND SAFELY ISOLATED BY AUTOMATIC MEANS

.

S

BREAKER:

T

HE BREAKER USE AT OUR

M

AIN

P

LANT AT

K

AHALGAON

STPP,

ARE OF

R

USSIAN MAKE

.

AIR

CIRCUIT

BREAKER.

I

TS RATINGS ARE AS FOLLOW

:

R

ATED

V

OLTAGE

:

6.6KV

M

AXIMUM

O

PERATING

V

OLTAGE

:

7.2KV

R

ATED

C

URRENT

:

1600:2500:3200

A

MPS

.

S

HORT

C

IRCUIT

C

URRENT

:

40KA

C

LOSING TIME

/

T

RIPPING TIME

:

<75

M

S

EC

1600

A

MP BREAKERS ARE USED IN ALL FEEDERS

,

WHEREAS

,

2500

A

MP BREAKERS ARE USED FOR

S

TATION

&

UAT

INCOMERS

.

T

HE

3200

A

MP RATED BREAKERS ARE USED IN

BV01,

BW01,

BL12,

BM12,

BV02

&

BW02.

T

HESE BREAKERS CONSIST OF A

900

W

ATT

.

U

NIVERSAL

.

S

PRING CHARGING MOTOR FOR CHARGING THE ACTUATING SPRINGS

.

A

BLOW OUT DEVICE IS ALSO FITTED IN THE BREAKER TO QUENCH THE ARE GENERATED DURING OPERATION OF THE SAME

.

T

HIS BLOW OUT DEVICE PUSHES THE ARC IN TO THE

ARC

CHUTE

AND EXPANDS THE SAME TO EXTINGUISH IN MINIMUM POSSIBLE TIME

.

T

HE BREAKERS ARE KEPT IN SPECIAL TYPE OF CABINET

,

WHERE DROPPERS OF BUS AND OUTGOING CABLES ARE TERMINATED

.

T

HESE BREAKERS OPERATES ON DUAL OPERATING SYSTEM

-

E

LECTRICAL

&

M

ANUAL

.

M

ANUAL OPERATION SHOULD BE DONE ONLY IN EMERGENCY

.

T

HE BREAKER OPERATES THROUGH

C

LOSING

&

T

RIPPING MECHANISM

,

WHEN A COMMAND IS GIVEN ELECTRICALLY

.

I

N THE CABINET

,

HIGH CLASS CURRENT

TRANSFORMERS

(CT)

ARE MOUNTED ON THE OUTGOING CABLE FOR THE

PROTECTION

AND

METERING

CIRCUIT

.

O

NE NUMBER

CORE

BALANCE

CURRENT

TRANSFORMER

(CBCT)

IS ALSO FIXED ON THE OUTGOING CABLE TO DETECT

EARTH

FAULT

IN THE EQUIPMENT OR CABLE

.

6.6

KV CIRCUIT BREAKER

A

CIRCUIT BREAKER IS A DEVICE WHICH

:-



M

AKES OR BREAKS A CIRCUIT EITHER MANUALLY OR BY REMOTE CONTROL UNDER NORMAL CONDITIONS

.



B

REAKS A CIRCUIT AUTOMATICALLY UNDER FAULT CONDITIONS

.



T

HUS A CIRCUIT BREAKER IS JUST A SWITCH WHICH CAN BE OPERATED UNDER NORMAL

&

ABNORMAL CONDITIONS BOTH AUTOMATIC OR MANUALLY

.

T

O PERFORM THIS OPERATION

,

A CIRCUIT BREAKER IS ESSENTIAL CONSISTING OF FIXED AND MOVING CONTACTS CALLED ELECTRODES

.

W

HEN A FAULT OCCURS ON POWER SYSTEM

,

THE TRIP COIL OF CIRCUIT BREAKERS ENERGIZED WHICH PULLS APART MOVING CONTACTS

,

THUS OPEN THE CIRCUIT DC SUPPLY IS USED FOR THE OPERATION OF CIRCUIT BREAKER

.

O

N THE BASIS OF MEDIUM USED FOR EXTINCTION THE CIRCUIT BREAKER ARE CLASSIFIED AS

:

1.

OIL CIRCUIT BREAKERS

2.

AIR BLAST CIRCUIT BREAKER

OIL CIRCUIT BREAKER

I

T IS WELL KNOWN THAT WHEN A CIRCUIT CARRYING A LARGE CURRENT IS BROKEN

,

AN ARC OCCURS AT THAT POINT WHERE THE CONTACTS ARE SEPARATE

;

THE ARCHING IS SPECIALLY SEVERE WHEN HIGH VOLTAGES ARE INVOLVED AND IF A SHORT CIRCUIT OCCURS ON A HIGH VOLTAGE CABLE WHICH IS SUPPLIED FROM LARGE POWER STATION

.

T

HE ARC WOULD BE POWERFUL TO BRIDGE THE CONTACTS OF THE SWITCH AND DESTROY IT BY BURNING

.

T

HE DEVICE IS EMPLOYED AS AN OIL BREAKER

.

A

N OIL BREAKER POSSES THE PROPERTY OF ALWAYS BREAKING AN ALTERNATIVE CURRENT AT ITS ZERO VALUE

.

T

HESE SWITCHES ARE SUITABLE FOR A MAXIMUM VOLTAGE OF

6.6

KV

.

T

HE CONTACTS OF THESE SWITCHES

,

WHICH BREAK HIGH TENSION CIRCUIT

,

ARE IMMERSED IN OIL TO ENSURE RAPID

&

EFFECTIVE RAPTURE OF THE CIRCUIT

.

W

HEN THE ARC OCCURS

,

THE OIL IN ITS PATH IS VAPORIZED AND THE GAS THEREBY GENERATED EXTRACT A PRESSURE ON THE SURROUNDING OIL

.

T

HIS PRESSURE IS UTILIZED IN ARC CONTROLLED DEVICES TO CAUSE A MOVEMENT OF FRESH COOL OIL ACROSS THE PATH OF THE ARC

,

THEREBY EFFICIENTLY ASSISTING ITS INTERRUPTION

.

2.

AIR BLAST CIRCUIT BREAKER

A

LL AIR BLAST CIRCUIT BREAKER REQUIRES AN AUXILIARY COMPRESSED AIR SYSTEM WHICH SUPPLIES AIR TO THE BREAKER AIR RECEIVER

.

W

HEN OPENING IS REQUIRED

,

COMPRESSED AIR IS ADMITTED TO THE ARC EXTINCTION CHAMBER

.

I

T PUSHES AWAY THE MOVING CONTACTS

.

I

N DOING SO THE CONTACTS ARE SEPARATED AND THE AIR BLAST TAKES AWAY THE IONIZED GASES ALONG WITH IT AND ASSISTS ARC EXTINCTION

.

A

IR BLAST CIRCUIT BREAKER EXTINGUISHES THE ARC

.

W

ITHIN ONE OR TWO CYCLE AND ARC CHAMBER IS FILLED WITH A HIGH PRESSURE AIR

,

WHICH PREVENTS RESTRIKE

.

3.

SULPHER HEXAFLURID CIRCUIT BREAKER

I

N

SF6

C

IRCUIT BREAKER

SF6

GAS IS BLOWN AXIALLY ALONG THE ARC

.

T

HE HEAT IS REMOVED FROM THE ARC BY AXIAL CONVECTION AND RADIAL DISSIPATION

.

C

ONSEQUENTLY

,

THE ARC DIAMETER REDUCES DURING THE DECREASING NODE OF THE CURRENT WAVE

.

T

HE DIAMETER BECOMES SMALL DURING CURRENT ZERO

.

T

URBULENT FLOW IS INTRODUCED AROUND

.

SAFETY:

T

HOUGH THE DESIGN OF THE BREAKER CABINET AT

K

AHALGAON IS VERY SAFE

,

BUT SAFETY ASPECT FOR

O

PERATION SHOULD NEVER BE OVER LOOKED

.

B

Y KEEPING A FEW THINGS IN THE MIND AND IN DAILY ROUTINE

,

M

ANY ACCIDENTS CAN BE AVOIDED

.

H

ERE ARE A FEW TIPS

,

WHICH AN OPERATION MAN MUST CHECK WHILE OPERATING THE BREAKERS

:

1. A

LWAYS SEE THE

EARTH

SWITCH

POSITION

,

WHILE RACKING

-

IN THE BREAKER

.

T

HE

E

ARTH

S

WITCH POSITION MUST BE IN

'OFF'

POSITION

,

WHEN THE BREAKER IS PUSHED IN

SERVICE

POSITION

.

2. N

EVER OPERATE

E

ARTH

S

WITCH OF

UAT,

S

TATION

I

NCOMER

,

BV01,

BW01,

BL12,

BM12,

BV02

OR

BW02

WITHOUT CONFIRMING THE PROPER ISOLATION

.

3. B

EFORE OPERATING

E

ARTH SWITCH IN A

T

RANSFORMER FEEDER

.

LT

I

NCOMER ISOLATION MUST BE CONFIRMED

.

4. A

LL FLAGS SHOULD BE RESET BEFORE SWITCHING ON THE CONTROL SUPPLY

.

5. N

EVER USE EXCESSIVE FORCE TO INSERT THE BREAKER IN TO

S

ERVICE POSITION

.

C

HECK THE FINGER CONTACT OF THE BREAKER AND

S

HUTTER MECHANISM OF THE CABINET

,

IF THE SAME IS NOT GOING IN THE

S

ERVICE POSITION

.

6. F

REENESS OF THE PAD LOCK SHOULD BE ENSURED AFTER PUTTING THE BREAKER IN

SERVICE

OR

TEST

POSITION

.

7. T

HE MULTI

-

PIN OF THE BREAKER SHOULD BE TIGHTENED AFTER KEEPING THE CONTROL SUPPLY OFF

.

8. T

HE DOOR OF THE BREAKER CABINET MUST BE CLOSED BEFORE MAKING THE CONTROL SUPPLY

'ON'.

EMERGENCY:

A

N OPERATION STAFF SHOULD KNOW TO COPE WITH EMERGENCY SITUATIONS

.

T

HE MAY ARISE IN CASE OF

DC

(C

ONTROL

S

UPPLY

)

FAILURE

,

B

LACK OUT

,

F

IRE

,

ETC

.

I

N CASE OF

DC

FAILURE

,

ALTERNATIVE SOURCE MAY BE SWITCHED

'ON'

WHOSE SWITCHES ARE IN SINGLE CONTROL CABINET

,

LOCATED AT THE BOTH END OF SWITCHGEAR

.

I

F THE

DC

SUPPLY DOES NOT RESTORE BY ALTERNATIVE SOURCE ALSO

,

ALL THE BREAKERS OF THE PARTICULAR BUS SHOULD BE MANUALLY TRIPPED IN CONSULTATION WITH

S

HIFT

-

IN

-

C

HARGE

,

AS ALL THE CONTROL

&

PROTECTION SYSTEM WILL BE OUT

.

T

HE SAME THING SHOULD ALSO BE DONE IN

B

LACK OUT CONDITION

.

I

N CASE OF FIRE

,

THE SUPPLY OF THE PARTICULAR FEEDER SHOULD BE MADE

OFF,

IF POSSIBLE AND THE

F

IRE

S

ERVICES MAY BE CALLED IN IMMEDIATELY

.

F

IRE EXTINGUISHERS MAY BE USED FOR PUTTING OFF THE FIRE

.

A

LL DOORS SHOULD BE OPEN AND VENTILATION FANS MAY BE SWITCHED ON

.

BASICS

OF

PROTECTIVE

RELAYING

I

NTRODUCTION

:

T

HE PURPOSE OF AN

E

LECTRICAL

P

OWER SYSTEM IS TO

G

ENERATE AND SUPPLY ELECTRICAL

E

NERGY TO THE

C

ONSUMER SAFELY

&

RELIABLY

.

T

HE PURPOSE OF A PROTECTIVE SYSTEM IS TO ISOLATE THE FAULTY SECTION OF THE POWER SYSTEM AS QUICKLY AS POSSIBLE FROM THE HEALTHY SYSTEM

:

(a) T

O AVOID DAMAGE TO THE HEALTHY PARTS OF THE SYSTEM

.

(b) T

O AVOID DAMAGE TO THE AFFECTED PARTS

.

(c) T

O AVOID LOSS OF SYNCHRONISM OF THE HEALTHY

G

ENERATOR OF THE PLANT

.

I

N ASSOCIATION WITH

C.T./P.T

AND

(C.B)

C

IRCUIT BREAKERS

,

THE PROTECTIVE RELAY AVERTS THE ABOVE EFFECTS

.

AC.T

/

P.T.

/

OR

C.V.T/

P

ROVIDED INFORMATION TO THE RELAY REGARDING THE ELECTRICAL STATE OF THE SYSTEM

;

W

HENEVER THE ELECTRICAL STATE OF THE SYSTEM GOES BEYOND A PREDETERMINED VALUE

,

THE RELAY GIVES A TRIPPING SIGNAL TO THE CIRCUIT BREAKER

;

THE CIRCUIT BREAKER THUS TRIPS AND DISCONNECTS THE FAULTY

E

LEMENTS OF THE POWER SYSTEM

.

C.B.

L

OCATION IS SO CHOSEN THAT EACH

G

EN

.

T

RANSFORMER

,

B

US

,

T

RANSMISSION

L

INE

E

TC

.

CAN BE COMPLETELY DISCONNECTED FROM REST OF SYSTEM

.

PROTECTIVE

RELAYS:

-

T

HE RELAY IS USED TO DETECT THE ABNORMAL CONDITIONS SUCH AS SHORT CIRCUITS

,

EARTHING OF LIVE EQUIPMENT

/

PARTS

,

OVERLOADS

,

OVER VOLTAGES

,

UNDER VOLTAGES

,

UNBALANCED LOAD

,

UNDER FREQUENCY

,

ABNORMAL GAS PRESSURE IN THE TRANSFORMER ETC

.

T

HE BASIC FUNCTION OF RELAY IS TO DISCONNECT THE FAULTY OR ABNORMAL SYSTEM EQUIPMENT THROUGH CIRCUIT BREAKER TO AVOID DAMAGE TO THE EQUIPMENT OR INSTABILITY OF THE SYSTEM IN THE SHORTEST POSSIBLE TIME

.

P

RIMARILY THE RELAY SOUNDS AN ALARM TO INDICATE EXISTENCE OF AN ABNORMALITY

.

N

ORMAL AND ABNORMAL CONDITIONS ARE DISTINGUISHED BY RELAY SENSING ELEMENTS WHICH REPPOND TO SET ACTUATING PARAMETERS LIKE CURRENT

,

VOLTAGE

,

PHASE ANGLE

,

FREQUENCY

,

WAVW SHAPE ETC

.

T

HE OPERATING PARAMETERS ARE

:

–

M

AGNITUDE

–

P

HASE ANGLE

–

D

URATION

(

TIME

)

–

R

ATE OF CHARGE

–

D

IRECTION

–

W

AVE

S

HAPE

ELECTROMAGNETIC

RELAYS:

O

PERATING

P

RINCIPLES

:

-

E

LECTROMAGNETIC ATTRACTION

-

E

LECTROMAGNETIC INDUCTION

-

T

HERMAL EFFECT

(

HEAT PRODUCED

I

2

R

T

.)

A

CTUATING STRUCTURES

:

-

S

HADED POLE STRUCTURE

-

W

ATT HOUR METER STRUCTURE

-

I

NDUCTION CUP

(S

IGNAL LOOP AND DOUBLE LOOP STRUCTURE

)

STATIC

RELAYS:

T

HE DEVELOPMENT OF STATIC RELAYS HAS BEEN VERY FAST AS THESE HAVE MANY ADVANTAGE AS COMPARED TO ELECTROMAGNETIC RELAYS

:

-

-

A

BSENCE OF MOVING PARTS

-

L

OW BURDEN ON

CT

S

&

VT

S

-

F

AST OPERATION

(

1-2

MS

)

-

H

IGH RESISTANCE TO SHOCKS AND VIBRATION

-

L

OW MAINTENANCE

-

M

INIATURIZATION

B

ASIC OPERATION OF THE STATIC RELAYS REVOLVES AROUND THE LINARY SIGNAL CONVERSION WITH MEASURING FUNCTIONS

.

T

HE TRANSDUCER ELEMENT SUCH AS CURRENT

,

VOLTAGE

,

PHASE ANGLE OR FREQUENCY AND DERIVED VALUES OBTAINED BY DIFFERENTIATION

,

INTEGRATION OR OTHER OPERATIONS IN THE CONVERTER SECTION APPEAR AS ANALOGUE INPUT TO MEASURING CIRCUITS

.

T

HE OUTPUT IS BINARY SIGNAL THE ACTUATING CIRCUIT

.