WELCOME

TRANSMISSION LINES DESIGN AND CONSTRUCTION

BYK.VEERABHADRA RAORETD.CHIEF ENGINEER,AP TRANSCO

DEVELOPMENT OF AC TRANSMISSION LINES16-5-1888 TRANSMISSION LINE PATENT GIVEN FIRST LINE 25 kV LINE LAUFFEN TO FRANKFURT IN GERMANY1912 110 kV LINE LAUCHLAMMER TO RIESA 17-4-1929 220 kV LINE BRAUWEILER TO FRANKFURT TOWERS DESIGNED FOR 380 kV5-10-1957 380 kV LINE ROMERSKIRCHEN TO LUDWIGSBURG- HOHENECH 1967 735 kV LINE IN HYDRO QUEBEC1982 1200 kV LINE IN SOVIET UNION EXTREMEMELY HIGH VOLTAGE TRANSMISSION BEYOND 2000 kV NOT PREFERED DUE TO HIGH CORONA DISCHARGELOSSES MORE THAN LOSSES DUE TO LINE RESISTANCE

DESIGN BASIS1.ECONOMIC FACTORS2.NETWORK SAFETY3.REDUNDANCY

MAIN COMPONENTS1.CONDUCTOR

2.CONDUCTOR ACCESSORIES a) REPAIR SLEEVES b) COMPRESSION JOINTS c) VIBRATION DAMPERS d) SPACERS / SPACER DAMPERS3.EARTH WIRE a) COMPRESSION JOINTS b) VIBRATION DAMPERS c) COPPER EARTH BONDS

4.INSULATORS

5. EARTHING/ COUNTER POISE EARTHING SETS

6.INSULATOR STRING HARDWARE a) SUSPENSION STRING HARD WARE b) TENSION STRING HARD WARE

7.OPGW

8.EARTH WIRE /OPGW HARDWARE

9.TOWERS

10.TOWER ACCESSORIES a) PHASE PLATES b) DANGER BOARDS c) BIRD GAURDS d) ANTI CLIMBING DEVICES e) STEP BOLTS

MAIN COMPONENTS contd..

CONDUCTORS1. COPPER 2 .COPPER CONDUCTOR STEEL REINFORCED3. ALUMINIUM4. ALL ALUMINIUM ALLOY CONDUCTORS(AAAC)5. ALUMINIUM ALLOY CONDUCTOR STEEL REINFORCED(AACSR)5. ALUMINIUM CONDUCTOR STEEL REINFORCED(ACSR)6. ALUMINIUM CONDUCTOR ALUMINIUM CLAD STEEL REINFORCED - ACSR(AS)

ADVANTAGES OF ACSR1. MORE SPAN-LESS SAG2. LARGER DIA -LESS CORONA LOSS FOR UHV LINES

STANDARDS1. IS:398 IEC-1098-1991: SPECIFICATION FOR ALUMINIUM CONDUCTORS FOR OVERHEAD TRANSMISSION LINES2 IS-398 PART-II : ACSR 3. IS-398 PART-V : ACSR FOR 400 kV AND ABOVE4. IEC-1232 : ALUMINIUM CLAD STEEL WIRES FOR ELECTRICAL PURPOSES5.IS-1778 :REELS AND DRUMS FOR BARE CONDUCTORS

PRINCIPAL PARAMETERS OF ACSR1. APPLICABLE STANDARDS 2. NO./WIRE DIA.AL./STEEL3. SECTIONAL AREA OF ALUMINIUM (SQ,mm)4. TOTAL SECTIONAL AREA (SQ,mm) 5. OVERAL DIA.(mm)6. APPROXIMATE WT(.KG / KM)7. DC RESISTANCEAT 20 DEG.C( OHM/KM)8. ULTIMATE TENSILE STRENGTH ( KN)9. FINAL MODULUS OF ELASTICITY (KG/cm)10. COEFFICIENT OF LINEAR EXPANSION (PER DEG.C)11.LAY RATIO( MAX./MIN.)12.TECHNICAL PARTICULARS OF STEEL AND AL.STRANDS a) strand dia. b) cross sectional area c) wt./km d) min.breaking load befor stranding and after stranding KN e)zinc coating of steel wire f) joints in strands g) chemical composition of steel wire

IMP. TYPE TESTS1.ULTIMATE TENSILE STRENGTH2.CORONA EXTINSION VOLTAGE3.RADIO INTERFERENCE VOLTAGE4.DC RESISTANCE5.STESS STAIN TEST This test is to collect the creep data of the conductor.Creep is due to settlement of strands and due to non -elastic elongation of metal when subjected to load.The manufacturer shall furnish the amount of creep in 10,20,30,40,50 years along with supporting calculations.The calculation to be based on every day temp. and tension 22 % of UTS. for 400 kV and 25 %UTS for 220 kV

INSULATOR STRINGS TYPES OF INSULATORS1. PORCELAIN DISC INSULATORS,LONG ROD INSULATORS2.TOUGHENED GLASS3.POLYMER SILICON RUBBER/ALLOY OF SILICON RUBBER AND EPDM

NORMAL SIZES1.254 X 145 mm 70KN/90KN EMS. 280mm CREEPAGE2.280 X 170 mm 120 KN/160KN, 280mm/330mm/430mm CREEPAGE 3.305 X 145 mm 120 KN, 280mm /330mm/430mm CREEPAGE4.305 X 170 mm 160 KN 280mm /330mm/430mm CREEPAGE BALL DIA--16mm, 20mm

INSULATOR STRINGS---- CONTINUEDTYPES OF STRINGS 1.SINGLE SUSPENSION 2.DOUBLE SUSPENSION 3.SINGLE TENSION 4. DOUBLE TENSION 5.V-SRTING

CONSTRUCTION WORKS1.SURVEYS a) ROUTE ALIGNMENT b) DETAILED SURVEYc) CHECK SURVEYi) PROFILESii) SOIL PARTICULARSiii) SAG TEMPLATE iv)TOWER SPOTTING v) RIGHT OF WAY

2. APPROVALS FROM CONCERNED a) ROAD CROSSINGSi) RAIL CROSSINGSii) TELECOM LINESiii) RIVER CROSSINGSiv) AIR PORT AUTHORITIES

CONSTRUCTION WORKS contd..3. FOUNDATIONS i) DESIGN FOR DIFFERENT SOILSii) EXCAVATION PLAN iii) FORM BOXESiv) STUB SETTINGv) CONCRETINGvi) REVETMENTSvii) EARTHING

4. TOWER ERRECTIONi) TOWER SCHEDULESii) INSEPCTION AND SORTING OUT MEMBERSiii) TREATMENT OF JOINSiv) ASSEMBLYv) TIGHTENING AND PUNCHING OF BOLTS AND NUTSvi) FIXING ACCESSORIES

CONSTRUCTION WORKS contd..5. INSULATOR HOISTING

6. POWER AND EARTH CONDUCTOR ERRECTIONi) DELIVERY OF CONDUCTOR AT SITE ii) PAYING OUT AND STRINGING iii) TENSIONING AND SAGGING iv) CLIPPING -IN

7. FIXING OF CONDUCTOR AND EARTH WIRE ACCESSORIES

8. FINAL CHECKING

9. TESTING AND COMMISIONINGi) CONDUCTOR CONTINUITY TEST ii) INSULATION RESISTENCE TESTiii) TO BE CHARGED AT LOW VOLTAGEiv) STATUTORY REQUIREMENTS TO BE MET

COST COMPONENTS1. TOWERS AND ACCESSORIES 28%2. ACSR CONDUCTOR AND ACCESSORIES 36%3. EARTH WIRE AND ACCESSORIES 01%4. INSULATOR AND STRINGS 06%5. FOUNDATIONS 04%6. ERRECTION 14%7. CENTAGES 11%

DESIGN BY PROBABILISTIC METHODIEC-826 CLIMATIC LOADSa) RETURN PERIODS OF CLIMATIC EVENTS 1) 50 YEARS2) 150 YEARS3) 500 YEARSb) DRAG COEFFICIENT OF CONDUCTOR c) TERRAIN CATEGORIES

DESIGN CONSIDERATIONSa) RELIABILITY (STRUCTURAL)OR PROBABILITY OF SURVIVALb) SECURITY (STRUCTURAL)c) SAFETY

DESIGN BY PROBABILISTIC METHODIEC-826 COORDINATION OF STRENGTH OF COMPONENTS--------------------------------------------------------------------------------------------------------MAJOR COORDINATION WITHCOMPONENT MA JOR COMPONENTS -------------------------------------------------------------------------------------------------------- TO FAIL FIRSTTANGENT TOWER TOWER,FOUNDATIONS, HARDWARE NOT TO FAIL FIRST ANGLE TOWER TOWER,FOUNDATIONS,WITH 90% CONFIDENCE HARDWARE DEAD END TOWER TOWER,FOUNDATIONS,HARDWARECONDUCTOR CONDUCTORS, INSUL- LATORS, HARDWARE

NOTE: WITH IN EACH MAJOR COMPONENTS THE UNDERLINED COMPONENT IS THE WEAKEST WITH 90% CONFIDENCE

LOADINGS ON TRANSMISSION LINES LIVE LOADS1. WIND LOADSa. NON-SNOWY REGIONSb. WITH ICE SNOWY REGIONSc. WITHOUT ICE SNOWY REGIONS2. DEAD LOADSa. WEIGHT OF TOWERb. WEIGHT OF CONDUCTORS,c. HARDWARE AND INSULATORS3. SPECIAL LOADSa. EXTERNAL LOADS DURING b. CONSTRUCTION AND MAINTENANACE

REQUIREMENT OF LOADS1.RELIABILITY REQUIREMENTS CLIMATIC LOADS UNDER NORMAL CONDITIONS

2.SECURITY REQUIREMENTS FAILURE CONTAINMENT LOADS UNDER BROKEN WIRE CONDITION

3.SAFETY REQUIREMENTS LOADS DURING CONSTRUCTION AND MAINTENANCE LOADS

METHODOLOGY FOR THE DESIGN OF TRANSMISSION LINESESTABLISH SAFETY REQUIREMENTSSELECT SECURITY REQUREMENTSSELECT RELIABILITYCALCULATE CONSTRUCTION AND MAINTENANCE LOADSCALCULATE LOADSRELATED TO SECURITYCALCULATE CLIMATIC LOADSCOMBINE ALL LIMITLOADSCHECK SAFETY REQUIREMENTSFROMNATIONALREGULATIONSCALCULATE STRENGTHNEEDED TO COMPLYWITH ALL LOADS ANDREQUIREMENTS

DESIGN COMPONENTSFOR LOADS ANDSTRENGTHREQUIREMENTS

TOWER OUTLINE1.TOWER HEIGHT

2.TOWER WIDTH

3.CROSS ARM WIDTH

ELECTRICAL CLEARANCES1. MIN.GROUND CLEARANCE 2. MIN.CLEARANCE ABOVE HIGHEST FLOOD LEVEL3. CLEARACE AND SWING ANGLES4. AIR CLEARANCE5. POWER LINE CROSSINGS6. TELECOM.LINE CROSSINGS7. RAIL TRACK CROSSINGS

DESIGN PARAMETERS

1.NO.OF CIRCUITS2.CLIMATIC CONDITIONSa. WINDb. TEMPERATUREc. ISOKERANIC LEVELd. SEISMIC INTENSITYe. ICE FORMATION3.ENVIRONMENT AND ECOLOGICAL CONSIDERATIONS4.CONDUCTOR5.EARTH WIRE6.INSULATOR STRINGS7.SPAN

LOADINGS1. CLIMATIC LOADS RELATED TO RELIABILITY REQUIREMENTS: WIND LOADSi) SNOWY WITH ICE ii) SNOWY WITH OUT ICE iii) NON SNOWY

2. FAILURE CONTAINMENT LOADS RELATED TO SECURITY REQUIREMENTS. i) LONGITUDINAL LOADS ii) TORSIONAL LOADS iii) ANTI CASCADING LOADS 3. LOADS DURING CONSTRUCTION AND MAINTENANCE LOADS RELATED TO SAFETY REQUIREMENTS.

LOADINGS contd..NATURE OF LOADS1. TRANSVERSE LOADS(T)WIND LOAD ON TOWER STRUCTURE, CONDUCTOR, GW & INSULATOR STRINGCOMPONENT OF MECHANICAL TENSION2. VERTICAL LOADS(V)SELF WEIGHTLOADS DURING CONSTRUCTION AND MAINTENANCE3. LONGITUDINAL LOADS(L) RELIABILITY CONDITION (NORMAL CONDITION),SECURITY CONDITION (BROKEN WIRE CONDITION) AND SAFETY CONDITION (CONSTRUCTION AND MAINTENANCE) HAVE ALL THE ABOVE LOADS UNDER THEIR LOADING COMBINATIONS. SAFTETY CONDITION HAS BOTH NORMAL AND BROKEN WIRE CONDITION.

ANTI CASCADING CHECKSALL ANGLE TOWERS SHALL BE CHECKED FOR ANTI CASCADING CONDITIONS WITH ALL THE CONDUCTORS AND G.W. INTACT ONLY ON ONE SIDE.

1. TRANSVERSE LOADS(T) :UNDER NO-WIND CONDITION

2. VERTICAL LOADS(V) :CONDUCTOR, GW WEIGHTS ON ONE SIDE ONLY, WEIGHT OF INSULATOR STRINGS AND ACCESSORIES

3. LONGITUDINAL LOADS(L):PULL OF CONDUCTOR/GW AT EVERY DAY TEMPERATURE AND NO-WIND APPLIED SIMULTANEOUSLY AT ALL POINTS ON ONE SIDE WITH ZERO DEGREE DEVIATION.

BROKEN WIRE CONDITION (BWC)SINGLE CIRCUIT: ONE PHASE OR GW BROKEN WHICH EVER IS MORE STRINGENT FOR A PARTICULAR MEMBER

MULTI CIRCUIT: SUSPENSION TOWER: ANY ONE PHASE OR GW BROKEN WHICH EVER IS MORE STRINGENT FOR A PARTICULAR MEMBER

SMALL ANGLE TOWERS: ONE PHASE AND GW OR TWO PHASES BROKEN ON ONE SIDE.

LARGE ANGLE TOWERS/DEAD END TOWERS: ANY THREE PHASES BROKEN ON THE SAME SIDE OR ANY TWO PHASES AND GW BROKEN ON THE SAME SIDE.

DESIGN OF TOWER MEMBERSSTRESS ANALYSIS:1. GRAPHICAL DIAGRAM METHOD: NOW OBSOLETE2. ANALYTICAL METHOD3. COMPUTER AIDED ANALYSIS: 3D ANALYSIS

SELECTION OF MATERIALi)BOLT DIAMETER FLARGE WIDTH16MM 45 MMii)MINIMUM THICKNESS: 5 MMLEG 4MMBRACINGS/REDUNDENT MEMBERSiii) GRADE OF STEEL :MILD STEEL AND HIGH TENSILE STEELiv) STENDERNESS RATIO:LEGS < 120BRACINGS < 200REDUNDENT < 250TENSION < 400

DESIGN OF TOWER MEMBERS contd..PERMISSIBLE STRESSES

SELECTION OF MEMBERS

BOLTS & NUTSi) CLASS 4.6 ULTIMATE BEARING STRESS - 4440 Kgf/cm2 ULTIMATE SHEARING STRESS - 2220 Kgf/cm2

ii) CLASS 5.6 ULTIMATE BEARING STRESS - 6322 Kgf/cm2 ULTIMATE SHEARING STRESS -3161 Kgf/cm2 FOR 16 mm DIA BOLTS

i) CLASS 4.6 ULTIMATE BEARING STRESS - 3552 Kgf IN 5mm TH.sECTION ULTIMATE SHEARING STRESS - 4464 Kgf SINGLE SHEAR

i) CLASS 5.6 ULTIMATE BEARING STRESS - 5058 Kgf in 5mm th. SECTION ULTIMATE SHEARING STRESS -- 63564464 Kgf SINGLE SHEAR

TESTING OF TOWERSTOWER TESTING STATION1. TEST BED2. PERMANENT ANCHORS: LONGITUDINAL MOST3. ARRANGEMENT FOR APPLYING THE COMBINATION OF LOADS4. ELECTRICAL WRINCHES (REMOTE CONTROLLED)5. INSTRUMENTS TO RECORD THE LOAD APPLIED:MECHANICAL SPRING GAUGES OR ELECTRICAL / ELECTRONIC TRANSDUCEROS/DYNAMO METERS6. CONTROL ROOM 7. THEODOLOTES TO OBSERVE DEFLECTION OF TOWER

TESTING1. BOLT SLIP TEST2. BWC/ANTI CASCADE CONDITION3. NC4. DESTRUCTION TEST

APPLICATION OF LOADSTRANSVERSE, LONGITUDINAL LOADS AND VERTICAL LOADS AT PEAK AND RESPECTIVE CROSS ARM POINTS.

WIND LOAD ON TOWER BODY SIMULATED ATA. G.W.B. CROSS ARM LEVELSC. WIND BELOW CROSS ARM LEVEL TO BE SIMULATED TO ACT AT BOTTOM CROSS ARM LEVELD. TOWER WITH EXTENSION AT TOP OF EXTENSION

QUALITY ASSURANCE PLAN1. QUALITY POLICY2. QUALITY CONTOL(QC) DEPARTMENT3. QUALITY PLANNING4. DESIGN AND DRAWING5. COMPANY STANDARDS6. INSPECTION EQUIPMENT, TOOLS AND GUAGES7. MATERIAL MANAGEMENT8. INSPECTION OF INCOMING MATERIAL9. BOUGHTOUT ITEMS10. IN-PROCESS INSPECTION11. DOCUMENTATION

DESIGN OF FOUNDATIONS1. TYPE OF LOADSa. COMPRESSION OR DOWN WARD THRUSTb. TENSION OR UPLIFTc. LATERAL FORCES OR SIDE THRUST BOTH, TRANSVERSE AND LOGITUDINAL DIRECTIONS

2. SOIL PARAMETERSa. LIMIT BEARING CAPACITYb. DENSITY OF SOILc. ANGEL OF EARTH FRUSTRUM3. SOIL INVESTIGATIONa. TYPY OF SOILb. GROUND WATER TABLE

DESIGN OF FOUNDATIONS contd..4. TYPES OF FOUNDATIONSa. NORMAL DRY SOIL FOUNDATIONb. WET SOIL FOUNDATIONc. PARTIAL SUBMERGED FOUNDATIONd. FULLY SUBMERGED FOUNDATIONe. BLACK COTTON SOIL FOUNDATIONf. PARITAL BLACK COTTON SOIL FOUNDATIONg. SOFT ROCK/FISSURED ROCK FOUNDATIONh. HARD ROCK FOUNDATIONi. SANDY SOIL FOUNDATION

DESIGN OF FOUNDATIONS contd..5. STRUCTURAL ARRANGEMENT OF FOUNDATIONa. PCC TYPEb. RCC SPREAD TYPEc. BLOCK TYPEd. UNDER CUT TYPEe. GROUTED ROCK AND ROCK ANCHOR TYPEf. PILE TYPEg. WELL TYPE

6. REVETMENT ON FOUNDATION

THE END