Ceb Standard Lines - English

8/12/2019 Ceb Standard Lines - English

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CEBSTANDARDLINES

1.Normalization

2.TermsofService

3.Criteriacosting

4.Pylons

5.Drivers

6.Insulators

7.Accessories

8.Grounding

9.Foundations

10.Construction


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SOGREAHElectrowatt PageInterconnectionofNorthernTogoandBenin StandardsCEBNorthern

Lines

SUMMARY

PURPOSEOF

REPORT..........................................................................................................................

I

1. STANDARDIZATION................................................................................................................. 1

1.1General................................................................................................................. ..........................1 1.2Standardization................................................................................................................. ...............1

1.3 Choice of standards....................................................................................................... ...............1

2. GENERAL TERMS OF SERVICE.............................................................................................. 32.1General............................................................................................................................................. 3

2.2 Climatic conditions in Togo and Benin............................................................................... 3

2.2.1 Temperature.. 4

2.2.2 Rainfallandhumidity.................................................................................................................. 4

2.2.3Wind.............................................................................................................................................

5

2.2.4 Keraunic level... 62.2.5Pollution...................................................................................................................................... 7

2.2.6Altitude.7

2.2.7Solarradiation.............................................................................................................................. 7

2.3 Conditions geological and geotechnical............................................................................. 7

2.3.1 Seismic activity................................................................................................................ 7

2.3.2 General soil characteristics............................................................................................... 7

2.4 Conditions electric............................................................................................................... 8

2.4.1 Nominal voltages of service............................................................................................. 8

2.4.2 Regime grounded neutral points....................................................................................... 8

2.4.3 Vector group of transformers.......................................................................................... 9

2.4.4 Voltagelevelsandisolation................................................................................................ 9

3.CRITERIAFORTHECALCULATIONOFWORKS............................................. ...........12

3.1Heatresistanceofconductorsandaccessories........................................... 12.........

3.1.1Phaseconductors............................................ ............................................. 12

3.1.2CableGuard............................................ .................................................. ....12

3.2 Mechanical works...........................................................................13

3.2.1 Assumptions basic weather.................................................................... 13

3.2.2 Keeping cables................................................................................................. 13

3.2.3 Keeping insulators.............................................................................................143.2.4 Keeping towers and foundations............................................................................ 14

3.2.5 Calculation of wind loads............................................................................... 16

3.3 geometric conditions....................................................................................18

3.3.1 Isolation Levels............................................................................................18

3.3.2 Distances to ground........................................................................................... 193.3.3 Distances between consoles........................................................................ 20


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3.3.4 Distance between conductors ............................................ ...................................... 20

3.3.5 Distances custody ............................................ .................................................. 20

3.3.6 Angle of protective cable guard ........................................ .......................... 21

4. PYLONS ................................................. ................................................ 22

4.1 Types of towers .............................................. ................................................. 22

4.2 Applicable Codes and Standards ............................................. ................................. 234.3 Characteristics constructive ............................................... ............................... 23

4.3.1 Features ............................................. ....................................... 23

4.3.2 Calculation Ranges ............................................ .................................................. ... 24

4.3.3 Materials and Assembly ............................................ ......................................... 25

4.3.4 25

4.3.5 Testing of towers ............................................ .................................................. . 26

4.3.6 Transposition of conductors ............................................ ................................... 26

5.DRIVERS................................................. ....................................... 27

5.1Natureandsectionofthephaseconductors.......................................... 27...............

5.2Natureandsectionearthwires.......................................... .......................28

5.3cable

optical

ground

(OPGW)

........................................

29

....................

5.3.1Transmissioncharacteristicsoffibercable......................................... ........29

5.3.2CodesandstandardsforOPGW........................................ ...................30

5.4ApplicableCodesandStandards............................................. ................................. 30

5.5

6.INSULATORS................................................. ............................................ 33


6.2Characteristicsofthe161kVinsulators............................................ 34.....................

6.3Compositionof161kVinsulatorstrings......................................... 35..............

6.3.1Phaseconductors............................................ ............................................. 35

6.3.2Cablesguardisolated........................................... ............................................. 35

6.4Characteristics

of

63

kV

insulators

............................................

.......................

35

6.5Compositionof63kVinsulatorstrings......................................... 36................

7.WEAPONSEQUIPMENT.............................................. ............................. 37

7.1General


7.3Reinforcementofprotection.............................................. ....................................... 37

7.4Spareconnectingchainstotheframe......................................... 38................

7.5Clips

7.6Armorrods

7.7Sleevesanchorandjunction.......................................... ........................... 39

7.8VibrationIsolators.............................................. ...................................... 39

7.9Counterweight

7.10MarkingAir............................................... ......................................... 39

8.GROUNDING.............................................. ........................................ 41

8.1Groundingtheshieldwires......................................... 41............................

8.2Groundingoftowers........................................... ...................................... 41

8.3Connectiontotheconductorisolated........................................... 41..........................

9.FOUNDATIONS................................................. ......................................... 42


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9.1General

9.2Typesof

9.3Calculationsoffoundations.............................................. ......................................... 43

9.3.1Calculationoftheextractionforce....................................... ..................................... 43

9.3.2Calculationofthecompressionforce........................................ .................................. 43

9.3.3Calculationofthefireplace........................................... .............................................. 44

10.CONSTRUCTION................................................. ................................ 45

1.10

10.2Repiquetage................................................ 45............................................

10.3TreeandBrushRemoval.............................................. ...................46

10.4Identificationofdamage.............................................. .............................. 47

10.5TracksAccess............................................. .............................................. 47

10.6Foundations................................................ ............................................... 48

10.6.1Reconnaissancefloor............................................. ............................................ 48

10.6.2Choixfoundations............................................. .............................................. 48

10.7Implementationofthebasesoftowers.......................................... 49.............

10.8Earthingoftowers............................................ .............................. 50

10.9

Installation

of

towers

..............................................

50

..................................

10.10Repairofdamage.............................................. ................................ 51

10.11Installationofinsulatorstringsandaccessories......................................... .51

10.12Drawandcontrolcables............................................ 52..........................

10.12.1Drawingcables............................................ ................................................. 52

10.12.2Manufactureofgasketsandclampsto....................................... ....................53

10.12.3Trimmingcables............................................ ............................................... 54

10.13Establishmentofmonitoringforms............................................ 54........

10.14Testingandreceiptofthecompleteline.......................................... 54............

Appendices

Appendix1 INVENTORYOFEXISTINGLINES


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ABBREVIATIONS

GENERAL ABBREVIATIONS

AAAC AlmelecAA Aluminium conductor ACSR Aluminum Conductor Steel Heating oil DDO

MCM MCM

MT Medium Voltage (11 kV - 33 kV) OLTC OLTC

ONAF mode forced air cooling

Cooling ONAN by natural air circulation

By year p.a.

Power factor fp p.m. Monthly

CDGI cable guard isolated

ABBREVIATIONS FOR ORGANIZATIONS / COUNTRIES

CEB Benin Electricity Community

CEET Electric Power Company of Togo

CTL Powerhouse Lom ECG Electricity Corporation of Ghana OTP Togolese Phosphates

Office SBEE Beninese Company Electricity and Water Company Togolese STS Steel

VRA Volta River Authority

UNITS

m l m l

C degrees Celsius s seconds

A amperes

V Volt

W Watt

VA Volt Ampere

var Volt Ampere reactive

Watt hour watt g gram

MULTIPLE

k kilo (103)M mega (106) G giga (109)


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PURPOSEOFREPORT

TheCommunautElectriqueduBenin(CEB)toldthegroupofEngineersSOGREAHElectrowatt

studiesdetaileddesignandtenderdocumentsoftheswitchyard161kVNorthernTogoandBenin

NorthSection

Atakpam

Kara

Djougou

Parakou

and

associated

items

Atakpam

and

Kara,

Togo,DjougouandParakouinBenin.Onthisoccasion,theCommunautElectriqueduBeninwished

toestablishstandardsandstandarddocumentsfortherelevantnetworkequipment(HVlinesand

HV/MV).

Phase1studycontractNo.001/CEB/DG/SAF/SEC/97referstothedesignanddefinitionoffacilities

andequipmenttypesforlinesandsubstationsoftheCEB.

Thisreportaimstodefineandjustifyfromthestudyofexistingfacilities,thedesignfeaturesthat

mustberetainedfortheelementsofthe161kVtransmissionnetworkoftheCEB,thatistosay,the

linesandpositions.

Volume

1

presents

the

CEB

STANDARD

LINES.

It

has

10

chapters

concerning

each

part

of

the

componentsofHVlines.Standarddocumentssuchasplansweredevelopedandareincludedin

Volume2 Mapsanddiagramstypes.

Volume3presentstheCEBSTANDARDPOST.Itcontains18chaptersrelatingtoeachstation

equipment,orbyvoltagelevelfortheequipment,orbytypeofequipmentcommontothejobs.The

principlesofruralelectrificationbyisolatedgroundwiresarealsodefined.Plansanddrawingskinds

ofitemsarepresentedinaseparatevolume(Volume4).

ItshouldbenotedthatChapters1and2arecommontobothvolumesoftexts(volume

1and3)theyestablishgeneralitiesaboutstandardizationanddefinethegeneralconditionsof

serviceinTogoandBenin(ratedvoltages,isolationlevels,weatherconditions,theneutral...).

1.STANDARDIZATION

1.1General

Standardizationmeanstheintroductionofstandards,iedefiningtheperformancerequirementsof

equipment,therecommendedvaluesforthesemethodsandperformanceverification.Forexample,

theyrecommendthespecifiedvoltages,thedimensionsofparts,tolerancesfromthespecified

valuesandthemeasurementprocedures.

1.2Standardization

Whilethestandardsrecommendthefunctionalcharacteristicsandconstructiononanationalor

internationalstandardizationisforanoperator(oruser)tomakeachoiceamongoptions

recommendedbystandards.Thegoalisareductioninthediversityofmaterialusedtoreducethe

numberofsparepartsandtodevelopproceduresforassemblyandmaintenancestandards.

1.3Choiceofstandards

Electrotechnicalequipmentofmostmanufacturersintheinternationalmarketaredesignedand

manufacturedbasedoninternationalstandardssuchasISO(InternationalStandardOrganization)


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andIEC(InternationalElectrotechnicalCommission).Therecommendationsofthelatterare

increasinglymonitoredastheyaredevelopedby43nationalcommitteesthatbringtogether

representativesofallrelevantprofessionsandrepresenting80%oftheworldpopulation.Inaddition

tothestandardspublishedbytheindustrializedcountrieshavegenerallybeenadaptedtoIEC

recommendations(likethoseoftheISO).

Allthe

recommendations

of

the

IEC

is

subject

to

regular

revisions

resulting

from

their

adaptation

to

newmaterialsandequipment.ManypublicationsandanannualcatalogispublishedbytheIEC.

ForthisreasontheIECRecommendationstobasehardwarespecificationsoflinesandsubstations

with,inaddition,areferencetospecificstandardsforitemsnotaddressedbytheIECasthequality

ofmaterials,surfacetreatments,etc..

Thelistofmainstandardswiththeirabbreviationsisgivenbelow.Theirnationalequivalentsmaybe

acceptedifitleadstoequipmentcharacteristicsequalorsuperior.

ISO:InternationalOrganizationforStandardizationIEC:InternationalElectrotechnicalCommission

DINDeutschesInstitutfrNormung

ASTM:

American

Society

for

Testing

and

Materials

NF:

French

Standards

(edited

by

AFNOR)

UTE

UnionTechniquedel'Electricit

IEEE:TheInstituteofElectricalandElectronicsEngineers,Inc.

BS:BritishStandards

2.GENERALTERMSOFSERVICE

2.1General

DefiningcharacteristicsoftheequipmentandassociatedstructuresfortheentirenetworkCEBmust

takeintoaccountdifferentclimaticandgeographicalconditionsencounteredthroughoutthe

territory

covered

by

the

two

countries,

Togo

and

Benin.

Theseconditionshaveaninfluenceon:

themechanicalequipmentthatmustwithstandthestressesduemainlytowindandearthquakes,

coolingthematerialwhichdependsontheambienttemperatureandaltitude,

thedielectricmaterialforisolationintheairdependsonitsdisruptivequalities,varydepending

uponhumidityandaltitudeandpollution.

Althoughtheconditionsofservicemayvarysignificantlyfromoneregiontoanother,economic

considerationsandoperatingrequireastandardizationofequipmentwhosefeaturesmustmeet,as

faraspossible,aswidelyaspossibletheconditionsofserviceprevailingthroughouttheterritory

coveredbythenetworkoftheCEB.

2.2ClimaticconditionsinTogoandBenin

BeninandTogoareamongthehotzoneandhumidcoastalcountriesofsubequatorialAfricanand

northernSudaneseclimate.Theclimateisdirectlyinfluencedbythewindsthatblowalternately


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fromnortheastduringthedry(Harmattan)andsouthwesternwetperiod(Monsoon).

ThevegetationischaracterizedbytheGuineansavannahtypewithriverslinedwithgalleryforests.

Meteorologicalservicesofbothcountrieswereconsulted,thevaluesoftherecordsavailableare

summarizedbelowandthevaluesusedforthedefinitionofstructuresandequipment.

2.2.1 Temperature

Maximum temperatures occur in March, while minimum temperatures are in January. There

is therefore a very rapid rise in temperature until the first rains followed by a gradual decrease

and a rebound from September.

Temperature

maximum minimum averageofthewarmestmonth Averageyearly

Atakpam 35.6 20.8 26.6 28.5

Sokode 37.7 17.6 27.2 29.3

Kara 38.3 15.7 27.1 30.1

Cotonou 34.5 20.0 27.1 28.4

Bohicon

38.6

18.0

27.8

30.0Save 38.8 16.7 27.5 29.7

Parakou 39.2 13.6 26.9 29.7

Kandi 42.2 11.7 28.1 32.6

Natitingou 40.7 14.0 27.1 30.0

Wecanconsiderthatthetemperaturevariationsacrossthecountryaresufficientlyhomogeneousto

retainonesetoftemperaturesapplicablethroughouttheterritorycoveredbytheCEBnetwork

whichis:

Maximumtemperature:42C

MinimumTemperature:12C

Averageannual

temperature:

27

C

2.2.2 Precipitation and humidity

Annual rainfall ranges from 1350 mm in Togo and Cotonou, Parakou and 1200 mm to 900

mm at Kandi in northern Benin. It is fairly evenly distributed between March and October

with monthly rainfall ranging from 150-400 mm.

The relative humidity is usually quite high from 80 to 90% with a decrease from South to

North.

The core values adopted for the works are:

Anannual

precipitation

of

1350

mm,

anaveragevalueoftherelativehumidityof95%inwetperiodsbetween40and90%bydryperiod.

2.2.3 Wind

The wind influence is dominant in determining the mechanical behavior of airlines and, to a

lesser extent, the structures of HV external. The general scheme wind daily is summarized in

the table below.


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DRY SEASON WET SEASON

morning Afternoon Tonight morning Afternoon Tonight

NORTH 3 to 5 m / s 4 t o 6 m/s Calme 3 to5 m/s 3 t o 5 m/s Calme

Northwest to east Southwesterly to northwesterly

CENTRECalme 3 t o 5 m/s Calme 3 t o 5 m/s 4 t o 6 m/s 1 t o 3 m/s

South-west to north-east Southwesterly

SOUTH 3 t o 5 m/s 5 to7 m/s 5 t o 7 m/s 2 t o 5 m/s 5 t o 7 m/s 5 t o 7 m/s

Southwesterly Southwesterly

Thereforebeadoptedforthewholeareaanaveragespeedofwindof6m/s.

maximumwind

Theaveragespeedrecordsrecordedisbetween29.1m/sbytheseaat25m/sinthenorthbut,

althoughtheareaisnotpronetocyclonesandhurricanes,speedscanbeachievedveryimportant:

!51m/sinCotonouMarch8,1962,

!45m/sinParakouMay3,1979,

!24m/sinNatitingouinOctober1961andJune1964

!23m/sinAtakpameinMarch1988.

TheaverageannualmaximumspeedsinCotonouon30yearsis21m/sand

From21to24m/sinParakoufollowingthereportingperiod.

Themonthly

maximum

speeds

are

given

in

the

following

table:

month

Stations JanFebMarch AprilMayJuneJulyAug.Sept.Oct.Nov.Dec.

Kandi 15 20 30 30 30 35 25 35 28 25 15 17

Nattingou 10 12 19 23 21 24 23 15 22 24 20 10

Parakou 20 23 23 26 45 29 22 16 33 21 23 15

Save 1519 28 28 20 21 19 10 20 19 15 14

Bohicon 1420 36 20 10 17 14 14 17 22 15 16

Cotonou 2634 51 38 33 27 21 23 21 29 28 18

Atakpame 10 8 23 20 12 14 10 10 10 10 8 9

Kara

109

10

14

11

9

119

10

8

89

Sokode 1012 11 9 9 8 10 8 13 10 7 10

NB: Statisticsupto1987

ThefiguresrepresenttheBeninmaximumspeedsrecordedfrom1965to1996.

ThenumbersofTogoarethemaximumspeedsrecordedfrom1987to1996.


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Giventheavailabledatawithalargestandarddeviationonspeed

Parakouandtheneedtosizethelinesforatimegreaterthanreturn

50years,themaximumwindspeedof32m/sor115km/hwasadoptedforthecalculationswith

theusualsafetycoefficients.

Withregardtothesimultaneityofmaximumwindsandtemperatures,wenotethatthemaximum

windsoccur

at

the

beginning

of

the

rainy

season,

the

result

of

thermal

phenomena.

The

study

of

distributionswinds temperaturesshowsthatthemaximumwindoccursatatemperaturecloseto

theaverageannualtemperature.Whenthetemperatureisminimum(January)thewindsdonot

exceed21m/s(35m/sx0.6)exceptinthecaseofCotonou(26m/sinJanuary).Thelattervalueis

notbindinginsofarsimultaneously,theminimumtemperatureinCotonou(20C)issignificantly

abovetheminimumtemperaturefortheselectedarea(12C).

minimumwind

Theminimumwindtobetakenintoaccountforthecalculationofthethermalcapacityofthe

conductorsissetequalto0.5m/swhichtakesintoaccounttheinfluenceofthetemperatureofthe

conductorsonthesurroundingair.

2.2.4Levelkeraunic

Kerauniclevelisdefinedasthenumberofdaysperyearwhenthunderisheard.Thislevelvaries

from80beachfrontinSokodeto158,141and107inKarainParakou,whichishigh.

Weadoptthemeanvalueof130overtheentireregioncoveredbytheCEBnetwork.

2.2.5Pollution

Exceptontheseafrontsubjecttosaltpollutionisnotencounteredmajorproblemsofpollutionother

thanthedustofsandandlateriteespeciallyduringHarmatan.

WeadoptthefollowingpollutionlevelsthatrefertoIECRecommendation815:Theareabetween

theseaand50kminlandisviewedwith

highlevelofpollutionwhichisaminimumcreepagedistanceof25mm/kV,

Theareasbeyond50kmfromtheseaareconsideredwithamediumlevelofpollutionwhichisa

minimumcreepagedistanceof20mm/kV.

2.2.6Altitude

Thealtitudeisstilllessthan1000m,itposesnoproblemfortheequipmentremaininginthe

conditionsdefinedbytheIEC.

2.2.7SolarRadiation

Dailysunshinedurationisbetween6and8hours.Giventhelatitudeoftheareabetween6and12degreesnorthlatitudeandaltitude,whichrarely

exceeds800m,solarradiationof

1000W/m2waschosen.

2.3Conditionsgeologicalandgeotechnical

2.3.1EarthquakeActivity

TheareaofTogoandBeninisclassifiedasanarea"0"iehavingnosignificantseismicrisk.


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2.3.2Generalcharacteristicsofsoil

Forundergroundcables,theconditionsusedare:

Temperatureofthesoiltoadepthof1m:25C,

Soilthermalresistivity:150K.cm/W.

2.4Conditionselectric

2.4.1Voltageratingsservice

TheCEBhasstandardizedhighvoltagesfollowing:

Transport:161kV

Smalltransport:a63kV(66kVvoltage,whichisonlyusedononeline,Kara Sokodisnota

standardvoltage).

33kVdistribution

Distribution:

20

kV

(to

compensate

for

voltage

drops

in

transformers,

their

standard

load

voltage

issetequalto161/22kV)

Tothislistwemustaddthespecificvoltage:

Cabledistributionofisolatedguard:34.5kV

Lowvoltagestandardusedforauxiliarypositionsare:

Variouspowersupplies:400/230VAC(thisvoltageisthenewIECstandardforLVdistributionon

thebasisofwhichBTdevicesarenowmanufacturedandreplacesthe380/220Vpreviouslyusedby

CEB)

Protectionrelays:125VDC

Telecommunications:48VDC

Radiocommunications:12VDC.

2.4.2Plangroundedneutralpoints

Methodsofgroundingadoptedfordifferentvoltagelevelsare:

161kVdirect

34.5kVdirect(orthroughafilterreactance/resistancebalancing)

20kVorresistancedirecte2

400V:direct

1thistensionisnotrecommended.Itisbettertouse34.5kVor161kVdependingonthecharges

andlengthsoflines


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2thegroundingresistanceispreferablebecausetheamplitudeofthefaultcurrentisknown(within

family)

2.4.3TimeIndextransformers

Couplingsandhournumbersofprocessorsaregenerallyasfollows:Type13Standardpost

161/34.5/22kV

Ynd1yn0

20/0,4kV:Dyn11

PostStandardType2

161/22kV:Ynd5

20/0,4kVtransformerandauxiliarygroundingZnyn(forusewith20kVwindingsindeltaonly)

Thewindingsarestar161kVforreasonsbothtechnicalandeconomicsuchas:

easeofgrounding

non

uniform

winding

insulation

possibilityofeasycatches.

Toeliminatetheadverseeffectsofharmonics3,thewindings20kVarespecifieddelta.Theindexof

realhourlyprimary(d1,d5,etc.)isapplicableonlyifaparalleloperationwithothersystemsis

required.

However,inallcasesthecouplingandtheindexscheduleshouldbecheckedifaparalleloperation

withexistingtransformersarerequired.

Whenthecoilis20kVdelta,auxiliarytransformerswillbethetypegrounding,coupledzigzagto

provideagroundreferencewiththepossibilityofaddingasecondarywindinginstarpowertothe

auxiliary,thusavoidingseparateauxiliarytransformer.

2.4.4VoltageLevelsandisolation

2.4.4.1Externalinsulationlevels

IsolationlevelsandcorrespondingexternalconformitytoIEC711areshowninthetablebelow.

Notethat,becauseofhighlightningrisk,isolationlevelsarethehighestchosentominimizetherisk

ofsurgecancausedamage.

3Seesection3Volume3forthedefinitionofpositionsoftype1and2.

Thevoltagelevelsofoperationare,asauthorizedbytheIEC71,ignoredtheseoperatingvoltages.

Nominal Voltage kV

Highest

voltage for

equipment

Um kV rms.

Peak voltage23kV (peak)

Withstand voltage

of short duration-

frequency kV rms.

Withstand voltage

surges from

lightning kV (peak)

20 24 20 50 125


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34,5 52,5 43 95 250

63 72,5 59 140 325

161 170 139 325 750

2.4.4.2IsolationLevelsInternal

HighisolationlevelslistedabovecanaddsignificantlytothecostofmaterialsincludingHTinsulated

windingssuchastransformersorinductors.

Whensuchmaterialisproperlyprotectedbyarresters,itispossibletoreducethelevelofisolation

andthereforethecostofconstructionmaterials.Thevoltagelevelsofisolationrecommendedin

thesecasesareshowninthetablebelow.

Highest voltagefor equipmentUmkV rms.

Peak voltageUm 23kV (peak)

Withstandvoltage of shortduration-frequency

kV rms.

Withstand voltage

surges from lightning

kV (peak)

170 139 275 650

Notethatthesereducedlevelsdonotapplytovoltagetransformers,whicharenotadequately

protected,giventherelativelylongdistancefromthelightning;highvoltagesarethenapplied.

2.4.4.3shortcircuitlevelsoftheinstallation

MinimumlevelsofshortcircuitfortheCEBnetworkequipmentarespecifiedinthetablebelow.

161 kVNord 12.5 kA161 kV Sud 17,5 kA

63 kV Nord etSud 10 kA

34,5 kV 8 kA

33 kV 12.5 kA

20 KV 12,5 kA

3.CRITERIAFORTHECALCULATIONOFSTRUCTURES

3.1Heatresistanceofconductorsandaccessories

Maximumtemperaturesofdrivershavebeenfixedsothattheirinfluenceonthemechanical

behaviorofconductorsandtheiraccessoriesmaybenegligibleinthecaseofcontinuouscurrentand

lowinthecaseofshortcircuitcurrents.

Theconductortemperatureattheonsetoftheshortcircuitwillbeconsideredlessthantendegrees

atthemaximumcontinuousoperatingtemperatureduetotheverylowprobabilityoftwo

simultaneousevents.


14/44

3.1.1Phaseconductors

forthecurrentcontinuousservice:limitedtemperatureat70Cmaximum.

Fortheshortcircuit:limitedtemperatureto170Cforastartingtemperatureof60Candduration

of1second.

3.1.2CableGuard

Shieldwiresusedforruralelectrification(ASCR)

!Forthecurrentcontinuousservice:limitedtemperatureat70Cmaximum.

!Fortheshortcircuit:limitedtemperatureto170Cforastartingtemperatureof60Cand

durationof1second.

Conventionalcableguard(steel)

!Fortheshortcircuit:temperaturelimitedto300Cforaninitialtemperaturecorrespondingtothe

most

stringent

conditions.3.2Mechanicalresistanceofstructures

3.2.1Assumptionsbasicweather

Loadstobeconsideredforcalculatingthestrengthoftheworkswillbethoseresultingfromthe

worstofthefollowingassumptions.

Ahypothesis(provideddaily)

!Theconductortemperatureistheaverageannualtemperature,

!Nowind.

HypothesisB(maximumwindcondition)

!Theconductortemperatureistheaverageannualtemperature,

!Thewindisup

HypothesisC(minimumtemperaturecondition)

!Thetemperatureoftheconductorsistheminimumtemperature,

!Thewindisreducedto0.6timesthemaximumwindspeed.Thevaluesoftemperatureandwind

areshowninChapter2.

3.2.2Maintenanceofcables

Phaseconductors

!ForhypothesisA,thetensionintheconductorsmustnotexceed20%ofthebreakingload

guarantee.

!ForCaseB,thetensionintheconductorsmustnotexceed40%ofthebreakingloadguarantee.


15/44

!ForCaseCthetensionintheconductorsmustnotexceed40%ofthebreakingloadguarantee.

Shieldwires

Theconditionsareidenticaltothoseofthephaseconductorswiththeadditionalconditionthatthe

arrowcorrespondingtohypothesisAisequalto85%ofthearrowofthephaseconductors.

3.2.3Maintenanceofisolators

Forthethreehypotheses(A,BandC),theelementsofsuspensioninsulatorstringsandanchormust

notbesubjectedtoforcegreaterthan1/3oftheirelectromechanicaltensilewarranty.Furthermore,

assumingbrokenconductor(with70%relaxation),thesuspensioninsulatorstringsshouldnotbe

subjectedtoforcegreaterthan60%oftheirtensileelectromechanicalwarranty.

3.2.4Maintenanceoftowersandfoundations

Forobviousreasonsofcostreductiondesign,manufactureandmaintenance,thepylonsarestill

groupedintoalimitednumberoffunctionaltypes.Eachtypeoftowerishowevercomposedofa

main

body

and

various

extensions

to

achieve

a

variable

height

tower

to

adapt

more

easily

to

the

ground.Mechanicalcalculationsaremadeonthebasisofstressescorrespondingtothemaximum

height.

Effortsontowersresultfromforcesgeneratedbythecablesandtheforcesgeneratedbythewindor

theconditionsofassemblyandmaintenancedirectlytothetowerstructure.Thecorresponding

assumptionsareclassifiedintonormalloadcasesandloadcaseexceptional.Thesafetyfactor

relativetoruin(yield)forthemediatorespectare:

Normalloadcases:

safetyfactor1.6

Loadcaseexceptionalsafetyfactor1.1

Forfoundations,thesafetyfactorsappliedtotheeffortsoftearingandoverturningmomentsare

thosetowersmultipliedbyacoefficientofincreaseequalto1.10toreflectthegreaterdispersionof

mechanicalpropertiesofthematerialsimplemented.

3.2.4.1Loadcasenormal

Chargesthatthemediamusttakeinclude:

effortsofthevariouscomponentsofthelinecreatedbythewind(lateralforces),

mechanicaltensionofwires(longitudinalforces),

weightofcables,insulatorsandaccessories(verticalforces).

Theforcesgeneratedbythewindonthecablesarecalculatedasdescribedinparagraph

3.2.5.Thewinddirectionistakentransversetotheaxisoftheline.


16/44

3.2.4.2LoException

betweenAssumpti!Pylonsaintact.Inconsidere

themaxi

adcaseexcealloadcases200and500onofacablelignment:ahecaseofadarelaxatioumvoltage

ptionalareconsiderm.Wedistinbreakhaseconducruptureofanofthecablofhorizontal

edassumingguishthefoll

tororshieldphasecondusintheoppdriver.This

maximumcowingexcep

wireisbrokectorononessiterange(ypothesisof

blevoltagerionalloadca

n,theotherideofapylouetotheinsacablebrea

angesequivases:

ablesareinsalignmentulatorstringkappliesto

lentto

talledandillbeequalto70eteorologic

al


17/44

assumptionsA,BandC.

!Cornertowers:twophaseconductorsoraconductorandashieldwirearebrokenintheweather

assumptionsA,BandC.

!Pylonsstop:twophaseconductorsoraconductorandashieldwirearebrokenintheweather

assumptionsA,

B

and

C.

Themostsizingistobeconsidered.

Hypothesismounting

Isappliedinthemiddleofallthebars,otherthanmainlegsandhavinganinclinationoflessthan30

,averticalloadof150daNcorrespondingtotheweightofanassembleranditstools.

Hypothesisguy

Assumethat,onatoweranyoneormorecablesareretainedonthesupporttocontroltheirblood

by

shrouds

of

slope

1:

3

anchored

to

the

ground

on

flat

terrain.

The

most

sizing

is

to

be

considered.

3.2.5Calculationofwindloads

3.2.5.1Effortwindontheconductors

Thewindloadoneachofthecables(withouttakingintoaccountthemaskingeffectofasub

Abundleofconductorsontheother)witharangeoflengthL,appliedtotheattachmentpointon

eachsupportframingthescopeandnormallyitisgivenbythefollowingformula:

Ac=q0.Cxc.d.The

where

q0=0.5..V2,givenreferencedynamicpressureasafunctionofthereferencespeedVofthewind

atthelocationofthelinewithq0inN/m2,V,expressedinm/sandthedensityofair(equalto

1.225kg/matatemperatureof15Candnormalatmosphericpressure)

Cxc=dragcoefficienttakenas1.0forstrandedconductors

d=diameterofcable

L=sumofadjacentspans.

3.2.5.2Effortwindoninsulators

ThewindstressoninsulatorstringsisgivenbyAi=q0.Cxi.if

where

q0=dynamicpressurereference

Cxi=dragcoefficienttakenequalto1.2


18/44

Si=areaoftheinsulatorstringprojectedhorizontallyontheverticalplaneparalleltotheaxisofthe

chain.

3.2.5.3Effortonwindtowers

Theforceofthewindonthetoweritself,assumedtoacthorizontallyandperpendiculartotheaxis

ofthe

line,

is

given

by:

AT=q0.CxT.ST

where

q0=dynamicpressurereference

CxT=dragcoefficienttakingintoaccountallthefacesofthepylontakenequalto2.9andfora

latticetower(whoseratioofcompactnessisgenerallyoftheorderof0.2)

ST=totalareaofonefaceprojectednormaltothefaceperpendiculartothewind,theotherface

being

taken

into

account

in

the

drag

coefficient.

3.3Conditionsgeometric

3.3.1IsolationLevels

Insulationlevelsofoverheadlinesshouldbesimilartotheapparatusofthepositionstowhichthey

areconnected.Buttheirsituationparticularlyexposedtoovervoltagesofatmosphericoriginmost

oftenleadstooverinsulatelinesrelativetopositionsinordertoreducethefrequencyofpickup

online.Theinsulationcoordinationofequipmentinthestationisprovidedbytheinstallationof

arrestersasclosetothismaterial.

Based on the recommendations IEC 71-1, the following isolation levels were adopted for thelines:

Nominal operatingvoltage of the systemconcerned(kV rms.)

Highest voltage network

(rated voltage) (kV rms.)Rated voltage impulsewithstand lightning(kV peak)

Rated impulse withstandshort-duration power-frequency(kV rms.)

161 170 750 325

63 72,5 59 140

34,5 52 250 95

Note:The

34.5

kV

voltages

in

fact

correspond

to

aphase

ground

voltage

for

the

cable

network

of

isolatedguardwhoshouldbeinsulatedforaratedvoltageof52kV.

3.3.2Distancetoground

Thedistancesofalllivepartstometalpartsgrounded(elementsoftowers)arebasedonthe

probabilityofsimultaneousoccurrenceofanovervoltageandtheunfavorablepositionofthe

energizedconductor.Wethereforediscernthethreefollowingprobabilities:


19/44

Highprobability(nowind):thedistancetogroundisslightlygreaterthanthedistanceintheair

recommendedbyIEC71soastocauseignitionprotectiondevicesbetweentheinsulatorstring

ratherthanadirectprimingbetweenadriverandthetowerstructure.

Averageprobability(lowwind)inwhichthedistancestogroundaresuchthatthereisno

breakdownforswitchingovervoltages.

Low(windup)inwhichthedistancestogroundaresuchthatthereisnobreakdowninthe

withstandvoltageofshortdurationpowerfrequency.

Thecorrespondingdistancesforthemainphaseconductors(ratedvoltage

170kV)andthoseofisolatedgroundwire(ratedvoltageof52kV)aregiveninthetablebelow:

rated voltage(kV)

* Distance ground

(mm)

Distancewithout wind(mm)

Distance withreduced wind(mm)

Distance withmaximum wind(mm)

52 480 500 300 NA

72.5 630 693 320 270

170 1500 1650 900 500

*ThesedistancestogrounddistancesareminimumrecommendedbytheIECforawithstand

voltagewithstandvoltageof250kVratedvoltageof52kVand750kVfortheratedvoltageof

170kV.

3.3.3Distancesbetweenverticalconsoles

Theverticaldistancebetweentheendsofbrackets(ortheverticaldistancebetweenphases)is

greaterthan4.5m.

LGPlans

SS

004,

SS

008

and

SS

LG

LG012

give

the

sketch

of

geometric

principle

of

verification

of

a

pylonalignment(typeA).SeeChapter4.

3.3.4Distancebetweenconductors

Theminimumdistancesbetweenphaseconductorsandbetweenconductorandgroundwirewillbe

calculatedusingthefollowingformulas:

Phasedistancewithsingleconductors:

ecs=0.6.m'.(fl)

+t1.3

!Phase

distance

drivers

paired

with:

ecjecs=+awhere:

m=coefficientofwindloadwithreduced(comparedtotheresultofwindloadsandtheweighton

weight)

arrowf=medianmaximumtemperatureinthecablel=lengthofthesuspensionchain

t1=minimumdistancetothegroundwithmaximumwind


20/44

a=distancebetweentwoconductorsofthesamedualbeam(0.40m)

3.3.5Distancescustody

Theminimumdistancesbetweenthelineconductorsandtheobstaclesare:

!ordinaryfieldandcultivated:7.0m

!houses:

5.0

m

!roadcrossings:8.5m

!railroadcrossings:9.0m

!crossingsofnavigablewaterways:9.0m

!Telecommunicationlinecrossings:4.0m

powerlinecrossing:4.0m

Generallythesedistancesareforthemaximumtemperatureconductors,withoutwind.

3.3.6Angleofprotectivecableguard

To

properly

protect

the

power

line

against

the

direct

lightning

strikes

on

the

conductors,

the

cable

guardispositionedsuchthatthephaseconductorsarebelowtwohalfplanesparalleltotheaxisof

theline,throughthesuspensionclampsoranchoringoftheshieldwireandforminganangleon

bothsidesoftheverticalequalto:

Caseofasingletowerwithshieldwire:thechoiceofa15degreeangleleadstoanelevationof

expensivetopofthetowerofabout6.20m(2.30mandto20degrees).Withanangleof25degrees

andalevelof130keraunic,estimatedthenumbertwoseedperyearandper100kmofline.With

anangleof20degrees,thenumberofseedfallstolessthan1seed,beyondtheadvantageof

reducingtheangleisfadingduetothegreaterheightoftheshieldwire.Itshouldconsider

standardizingtripping/resinglephasecouplingsthatlimitlotdisturbanceonthenetworkincaseof

loveatfirstsight,therefore,thevalueof25degreeswasadopted.

Caseoftwotowerswithgroundwiresisolated:15degrees,avalueeasilyobtainedwiththetwo

consolessupportingwires.

Caseofdoublecircuittowers:thevalueof15degreesisadoptedforthesamereasonsasbefore.

Doublecircuittowersareequippedwithtwowires.

4.TOWERS

4.1Typesofpylons

giventhehomogeneityoftheterrainencounteredinBeninandTogo,threetypesofmediaare

sufficienttomeetvirtuallyanyeconomicconditions.Functionsandconditionsofuseofeachof

thesetypesaredefinedbelow:

TypeA Pylonalignment:

Equippedwithsuspensioninsulatorstringsandcanalsobeusedifnecessaryasasupportforlow

angle(0to2degreesmaximum)subjecttowindrangebelow300m.Thefollowingcurveshowsthe

valueoftheangledependingonthescope.


21/44

Anglededviation

()

Towerhasalignment

DeflectionanglerelationshipScope

3

2

1

Porte vent (m)

0 100 200 300 400

Type B - Pylon low angle (0 -30 ) and anti-cascade:

Equipped with anchor insulator strings, it is used:

as a support for up to 30 degrees angle (normal load case) and will be capable of

withstanding a voltage difference of longitudinal 10 to 15% in case of different parameters in

the adjacent townships; as carrier anti-Cascade to limit the length of a township 10 km

(enhanced security).

Type C - Pylon high angle (30 -60 ) and tower anchor:

Equipped with anchor insulator strings, it is used:

as a support for a high angle, between 30 and 60 maximum (normal load case) and will

be capable of withstanding a voltage difference of longitudinal 10 to 15% in case of different

parameters in the adjacent townships;

as base material for stopping the line (end supports) complete (drivers and ground wires),

one side in the absence of all cables on the opposite side in the event weather A; the existence

of the scope reduced voltage connection to the post will not be taken into account.

4.2 Applicable Codes and Standards

IEC 652 Mechanical testing of overhead line towers

IEC 826 Loading and strength of overhead transmission lines

4.3 Characteristics constructive


22/44

4.3.1 Features

The pylons are made of a mesh, square base, galvanized steel. They have four feet fitted with

separate sockets set into the foundation blocks. In order to adapt to site conditions, each type

of tower includes:

! A main body may be reduced or extended by extensions height. For the pylon alignment(type A) extensions will achieve the heights -6 m, and 0

6 m and the angle towers and anchor (type B and C), -6 m height and normal height.

! A series of interchangeable feet from -2.0 m to 3 m in 1 m for use in hilly terrain. These feet

are connected to the body by a specific junction piece (intermediate beam) to each extension

(6 m, 0,-6m) so as to use the same set of uneven feet per type of tower (see LG plane SS

005). Leg length is standardized.

The weapons pylons, which depend on the electrical characteristics of the line, will be chosen

from the following options:

Threeconductors

arranged

in

atriangle

and

aground

wire

in

the

case

of

single

line

dull,

6conductorsarrangedinaflagandguardcableinthecaseofdoublecircuitline,

Threeconductorsarrangedinatriangle(or6conductorsarrangedinflag)andtwoinsulated

shieldwiresifthepowerlineisalsousedforpowerdistributioninruralareas.

Itshouldbenotedthatforsimplepolesdullweaponsmostcommonlyusedare:

thehorizontalsheet,

type"chat",wherethehorizontalsheetisslightlyraisedcentralphasewhichallowsareductionof

thetotal

width

of

the

pylon,

thetriangulararrangement.

Thefirsttwotypesofweaponsrequiretwooverheadgroundwiresandaremorecomplextostudy

andbuildup.Byarmingagainsttriangle,usedonmostlinesCEBisagoodcompromiseandleadstoa

simpleframe,economicandachievablethroughlessspecializedmanufacturers.

PlansSS001toSSLGLG012givesthegeneralshapeanddimensionsofstandardtowershieldwire

toearth,simpleanddoublecircuittwoshieldwiresinsulatedornotinsulatedwithblueprintsswing

toweralignment(typeA).

4.3.2Calculation

Ranges

giventherelativelyflatprofileofthetwocountries,theincreaseofcalculationareasfollows:

suspension anchora

scope wind 400 m 400 m

weight range 600 m 800 m


23/44


24/44

Alltowers20,aplateofthepatterndefinedontheSS017andLGfortrackingthehelicopterisfixed

totheupperpartofthepylon.

Theplatesarealuminumalloy;weatherresistant(rain,sun)andthewritingwillbestampedand

paintedwithindeliblepaint.

4.3.5Testingofpylons

ThepylonsaretestedinafullscaleteststationandspecializedaccordingtoIEC652

recommendation.

Atowerofeachtypeistesteduptodesignloadsforeachcase.Inadditionthetoweralignmentwill

betriedatbreak.

4.3.6Transpositionofconductors

Inordertoimprovethebalancingofthecurrentsandvoltagesinthethreephases,wherethelines

or

line

sections

than

100

km,

it

is

necessary

to

perform

a

transposition

of

the

conductors.

Thisistoensurethateachoftheconductorsoccupieseachofthethreegeometricpositionsonone

thirdofthelengthoftheline.

Transpositionmustbecompleteandconsistsofthreesuccessiverotationsof1/3.Anexampleof

rotationisindicatedintheplanfortheSS014LGsimplelinesanddullontheLGSS015fordouble

circuitlines.

5.DRIVERS

5.1Natureandsectionofthephaseconductors

Currentlythe

most

commonly

used

cables

for

high

voltage

lines

are

aluminum

conductors

with

steel

coresonknownbythediminutiveofACSR(AluminiumConductorSteelReinforced)conductors

homogeneousaluminumalloyknownbythediminutiveofAAAC(AllAluminiumAlloyConductor)

andtoalesserextent,aluminumalloyconductorswithsteelcoresonknownbythediminutiveof

ACAR(AluminumConductorAlloyReinforced).

AAACconductorsareincreasinglyusedbecausetheyoffermanytechnicaladvantagesoverthe

ACSR:

theyareabout25%lighter,whichresultsinlowertensileidenticalboomandeasierhandlingof

cabledrums,generallyequivalenttotheelectricalpylonstheyleadtolighterandlongerspans,so

fewerpylons,becauseoftheirhomogeneousnature(theyareformedonlysonalloy)theybehave

wellwithrespecttocorrosion,thestressesarebetterdistributedinthesectionandthereforethe

jointsandanchorclampsaresimplerandsafer,

thesurfacehardnessofthealloysonistwicethatofthesonofaluminumwhichmakesthemless

susceptibletoinjuryduringpeelingthusreducinglossesandcoronaandaudiblenoise.


25/44

Theirothercharacteristicssuchascreepbehaviorandfatigueresistanceareidenticaltothoseof

ACSR.Theonlydrawbackisduetotheirlightness,whichgivesthemagreatertendencytoswingto

betakenintoaccountinthedesignofthemasthead.

Insummary,wecanconsiderthattheAAACconductorsleadtoasavingofabout5%ofthecostofa

line.

RegardingdriversACAR,studiesshowtheyrarelyleadtomoreeconomicalsolutionsthatAAAC.

AsaresultoftheanalysisabovetheAAACconductor500MCM,alreadyusedonseverallinesofCEB

networkwasadoptedasstandardcable.Indeedhissection

253.35mm2,whichcorrespondstoapowerratingof138MVA(inabsenceof

andwindforamaximumconductortemperatureof70C)at161kV,iswellsuitedtohighpowerto

passthroughthesouthernpartofthenetworkwhereenergysourcesaswellasmodestpowersover

largedistancesofNorthernnetwork.

5.2

Nature

and

section

overhead

ground

wires

Theshieldwireshavemultipleroles

theyareusedmainlytoreducetherateofinitiationofisolationbylightning,especiallyinthecaseof

highvoltages,

beingconnectedtothegroundtheysignificantlyreducethevoltagesinducedbythelinesHTinthe

telecommunicationscircuitsparalleltotheselines,

theycanbeisolatedandfedintoMTbeusedforruraldistribution,

telecommunicationcircuits(telephonesonoropticalfibers)canbeincorporatedintowires.

Proofofthenumberofshieldwires(0,1or2)isbasedonthestudyoftherateofinitiationto

lightningstrikesor,forinsulatedcablesonthetypeofruraldeliverydesired(singleorthreephase).

Thetypeandsectionoftheshieldwireisdeterminedbymechanicalconsiderations(arrowlessthan

orequaltothatofthephaseconductors)andelectrical(currentwithstandshortcircuit).

Giventhelowlevelofshortcircuit,acableguardmadeofgalvanizedsteelismostsuitableforlarge

spans

without

problems

boom.

The

section

71.3

mm2

cable

that

can

withstand

a

short

circuit

currentofabout5.5kAfor1secondandisalreadyusedbytheCEB,wasadoptedasthestandard

groundwireuninsulated.

WithrespecttotheshieldwiresinsulatedcablewasselectedbyVRAACSRusedformanyyearsand

isidealforitstwofunctions,protectionagainstlightningandruraldistribution.AAACcableisnot

suitabletotheconditionofguardcablesaglowerthanthephaseconductorsand,becauseofitslight


26/44

weightincreasestheriskofvibration.ACARcablebecauseofitsgreaterresistancetothesamecross

sectionistooexpensive.

5.3cableopticalground(OPGW)

Tomeetthegrowingneedsofinformationtransmission,theCEBhasselectedasthetransmission

mediumto

high

capacity

and

high

flow,

the

optical

fiber.

The

airlines

are

apreferred

medium

for

installingopticalfibers.ThesewillbeinstalledinacableguardlinesHT.

TheOPGWopticalfiber24includesstandardinstallation.

Thetypeandsectionoftheshieldwireisdeterminedbymechanicalconsiderations(arrowlessthan

orequaltothatofthephaseconductors)andelectrical(currentwithstandshortcircuit).Thesesame

considerationsapplytotheOPGW.Thejunctionboxesareinstalledatthebottomofthetower,just

abovetheanticlimbing.

When

the

OPGW

is

used

more

for

rural

delivery,

it

is

subjected

to

a

voltage

and

current

in

steady

statewhichconstituteadditionalconstraintstoconsiderinthechoiceofcable.Theseconstraints

leadtofurtherisolatethemassjunctionboxes.Thevoltageofthejunctionboxwillbethesame

potentialasthecableandjunctionboxesarethereforeplacedontopofpostinsulators.

5.3.1Transmissioncharacteristicsoffibercable

Mode field diameter 1310 nm 9,3 0,5 !m

Average attenuation at 1310 nm " 0,34 dB/km

Average attenuation at 1550 nm " 0,20 dB/km

Chromatic dispersion at 1310 nm 2,8 ps/(nm.km)

Chromatic dispersion between 1285 and 1310 nm 2,8 ps/(nm.km)

Chromatic dispersion at 1550 nm 2,8 ps/(nm.km)

Chromatic dispersion between 1525 and 1575 nm 2,8 ps/(nm.km)

zero dispersion Entre 1300 et 1325 nm

Zero dispersion slope 0,092ps/(nm.km)

Cut-off wavelength of the fiber 1280 nm

5.3.2CodesandstandardsforOPGW

IEEEStd1138 StandardConstructionofCompositeFiberOpticGroundwireforuseonElectric

UtilityOverheadPowerLines.(Standardcableconstructionofopticalgroundcompositeforuseon

overheadpowerlinesofpublicpowerdistributionnetwork)


27/44

ASTMB415 StandardSpecificationforHardDrawnAluminumCladSteelWire.(Standardforcold

workedsteelcablescladaluminum)

ASTMB230 StandardSpecificationforAluminum1350H19WireforElectricalPurposes.(Standard

foraluminumcable1350H19purposeelectrical)

ASTMB398 StandardSpecificationforAluminumAlloy6201T81WireforElectricalPurposes.

(Standardforcablesaluminumalloy6201T81purposeelectrical)

IEC7931 FiberOptics GenericSpecification

IEC7932 FiberOptics ProductSpecifications

IEC7941 Opticalfibercables Part1:Genericspecification

CIS825 Radiationsafetyoflaserproducts,equipmentclassification,requirementsanduser'sguide

IEC

874

1

Connectors

for

optical

fibers

and

cables

Generic

specification

IEC8751 Couplingdevicesforopticalfibers Genericspecification

EIA598A OpticalFiberCableColorCoding.(Colorcodingoffiberopticcable)

5.4ApplicableCodesandStandards

Generally,driverswillmeetthefollowingstandards:

ACSRCanadianCSAStandardC49

CablesAAACFrenchStandardC34125

IEC1597Conductorsforoverheadelectricallines.Calculationmethodforstrandedconductors.

5.5Characteristics

Unlessotherwisespecifiedcabletypestouseare:

cablesaluminumalloy(AAAC)forthephaseconductors,

thegalvanizedsteelwireforcableguardtraditional

aluminumsteelcables(ACSR)fortheshieldwiresusedforruraldelivery.

Thetechnicalcharacteristicsofcablephaseconductorsareshowninthefollowingtable:

designation Unit Phase conductor

Nature AAAC

denomination 500 MCM

total section mm2 253,35


28/44

Section aluminum mm2 253,35

Steel section mm2

outside diameter mm 20,6

Son number and diameter of aluminum mm 19 x 4,12

Son number and diameter of steel mm

Minimum breaking load daN 7235Final modulus of elasticity hbar 6300

Coefficient of linear expansion 10-6/C 23

Mass (ungreased) kg/km 698

Maximum DC electrical resistance at 20 /km 0,1322

Manufacturing standard ASTM B 399

Technical characteristics of overhead ground wires are shown in the following table:

designation Unit Single shieldwire

Guard cable

isolates

nature galvanized ACSRdenomination Minorca

total section mm2 71,3 88,90

Section aluminum mm2 56,13

Steel section mm2 71,3 32,77

outside diameter mm 10,8 12,22

Son number and diameter of aluminum mm 12 x 2,44

Son number and diameter of steel mm 7 x 3,6 7 x 2,44

Son number and diameter of steel daN 8800 5125

Final modulus of elasticity hbar 17200 10000 (*)

Coefficient of linear expansion

10-6/C 11,5 15 (*)

Mass (ungreased) kg/km 560 412

Maximum DC electrical resistance at 20 C /km 0,5161

Manufacturing standard DIN48-201 ASTM B 232

(*): Estimated values

Greased the cables should be avoided.

Cables present the complete mechanical and chemical characteristics specified in the

standards mentioned above.

Inaddition:

Eachofsonwillhavebefreeofscratchesandburrsduetostretchingandofsuperficialdefects.

Sonsectionwilldrawnearaspossibletotheperfectcircle.Thesuccessivelayersofcableswillbe

wiredinoppositedirections.

Thedirectionoflayoftheouterlayersofsonwillberight(cablingtypeZ).

Thenumberandmannerofexecutionofweldseligiblesoninelementarycablesshallconformto

thestipulationsofthestandardquotedabove.However,noweldingshallbepermittedinthe

strandsoftheouterlayerofcable.


29/44

Everysonofsteelcableguardwillbegalvanizedbyimmersioninabathofmoltenzinc.The

coatingwillhaveathicknessuniformandaccedesfirmlytosteel.Thegalvanizedwireshallbe

smooth,therewillbenonudebeachresultingfromthepresenceofscales.

6.INSULATORS

Theinsulatorstringsofthemaindriversareflexibleandcompositeinsulatorsofcapandpintype.

Theinsulatorstringsofoverheadgroundwiresareinsulatedfromtherigidtype.

6.1ApplicableCodesandStandards

IEC120Dimensionsofplebeianassembliesandsocketelementsinsulatorstring.

IEC305Insulatorsforoverheadlinesofnominalvoltageabove1000V.Insulatorunitsofceramic

materialorglassforacsystems.Characteristicsofinsulationelementsofcapandpintype.

IEC

372

A

lock

assembly

for

ball

and

socket

couplings

of

string

insulators.

Dimensions

and

tests.

IEC383Insulatorsforoverheadlinesofnominalvoltageexceeding1000VIEC437TestofRadio

Interferenceofhighvoltageinsulators.

CIS507Artificialpollutiontestsonhighvoltageinsulatorsforacsystems

IEC575endurancetestthermomechanicalandmechanicalendurancetestonstringinsulator.

IEC591Ruleofsamplingandacceptanceofasupplywhenapplyingstatisticalcomputingwith

mechanicaltestingofinsulatorsofceramicmaterialorglassforoverheadlinesofnominalvoltage

exceeding1000V

IEC797Residualstrengthofstringinsulatorunitsofceramicmaterialorglassforoverheadlines

aftermechanicaldamageordielectric

IEC815Guidetotheselectionofinsulatorsinpollution

6.2Characteristicsofthe161kVinsulators

Theinsulatingpartglasswaschosenbecauseexperienceshowsoperatorsthattheglasswasmore

suitableforaeriallineasporcelain.Indeedporcelaincracksbutdoesnotflyapartwhatisbestfor

busbarswhentheglassbrokeallowingamucheasieridentificationoffaultsonoverheadlines.

Thematerialsofthevariouspartsconstitutingtheinsulatorsare:

insulatingpart:temperedglass,

cover:galvanizedmalleableiron,

pin:forgedsteelgalvanized,

Sealing:cementwithappropriatethermomechanicalcharacteristics,


30/44

pin:phosphorbronzeorstainlesssteel.

ThecharacteristicsanddimensionsofthemainconductorsinsulatorscomplywithIEC

recommendationsandindicatedinthetablebelow.

designation Unit Suspension anchorage

Not rated nominal diameter shank

diameter

Length of the total leakage

approximate weight

Withstand voltage 50 Hz Dry

Withstand voltage 50 Hz in the Rain

Withstand voltage 1,2 / 50! S, dry

perforation 50 Hz voltage in oil minimum

breaking load electromechanical

mm

mm

mm

mm

kg

kV

kV

kV

kV

kN

255 or280

146

16

318 or445

3,7 or 5,6

70 or 85

40 or 50

100 or125

130

100

255 or280

146

16

318 or445

3,7 or 5,7

70 or 85

40 or 50

100 or 125

130

100

Note:Thetwolengthsoflineleakindicatedcorrespondtoinlandareasandcoastalareas.

Itshouldbenotedthattheinsulatorchainsanchorchainsandsuspensionareidentical.Although

insulatorswithabreakingloadof70kNaresufficient,thischoiceavoidsanyconfusionthatcouldbe

dangerous,insulatorsbetween70kNand100kNwhoseexternalappearanceisthesameinspiteof

differentcharacteristics.

6.3Compositionof161kVinsulatorstrings

6.3.1Phaseconductors

Giventheisolationleveladoptedforlines161kVto750kV,theinsulatorstringscanbesingleor

double,andconsistof11cellsconnectedinseriestothesuspensionchainsand12cellsinseriesfor

anchorchains.Theadditionofanadditionalinsulatorstringsanchorisintendedtopromotethe

initiationofthesuspensionchains,littlemechanicallyloaded,ratherthantheanchorchains.

Thedoublesuspensionchainandanchorareprovidedonlyforcrossingmainroads,crossingsof

otherpowerlinesortelecommunicationmajor.

Highmasthighangle,asuspensionchainisattachedtotheendconsolesforretainingstrapsofthe

outerconductorsatthecorner.Thesechainsareprovidedwithacounterweighttolimittheswing.

6.3.2Cablesguardisolated

thecharacteristicsanddimensionsoftheinsulatorstringsfortheshieldwiresareisolatedasfollows

(accordingtoIEC383):

designation Unit

nominal diameter mm 255

Number of elements 3

not rated mm 545


31/44

Length of the total leakage mm 1 200

Withstand voltage 1,2 / 50 s, dry kV 260

Withstand voltage 50 Hz Dry kV 190

Withstand voltage 50 Hz in the Rain kV 130

Minimum tensile electromechanicalkN 50

6.4 Characteristics of 63 kV insulators

The materials of the various parts constituting the insulators are:

! insulating part: tempered glass,

cover: galvanized malleable iron,

pin: forged steel galvanized,

Sealing: cement with appropriate thermo mechanical characteristics,

pin: phosphor bronze or stainless steel.

The characteristics and dimensions of the main conductors insulators comply with IEC

recommendations and indicated in the table below.

designation Unit Suspension anchorage

Not rated nominal diameter shank diameter

Length of the total leakage

approximate weight

Withstand voltage 50 Hz Dry

Withstand voltage 50 Hz in the Rain

Withstand voltage 1,2 / 50! S, dry perforation 50

Hz voltage in oil minimum breaking loadelectromechanical

mm

mm

mm

mm

kg

kV

kV

kV

kV

kN

255

127

16

320

3,5

70

40

100

130

70

255

127

16

320

3,5

70

40

100

130

70

6.5Compositionof63kVinsulatorstrings

Giventhe

isolation

level

adopted

for

the

63

kV

lines,

which

is

72.5

kV,

the

insulator

strings

can

be

singleordouble,andconsistoffourelementsconnectedinseriestothesuspensionchainandfive

cellsinseriesforanchorchains.Theadditionofanadditionalinsulatorstringsanchorisintendedto

promotetheinitiationofthesuspensionchains,littlemechanicallyloaded,ratherthantheanchor

chains.

Thedoublesuspensionchainandanchorareprovidedonlyforcrossingmainroads,crossingsof

otherpowerlinesortelecommunicationmajor.


32/44

Highmasthighangle,asuspensionchainisattachedtotheendconsolesforretainingstrapsofthe

outerconductorsatthecorner.Thesechainsareprovidedwithacounterweighttolimittheswing.

7.EQUIPMENTWEAPONS

7.1General

IngeneralthelineaccessoriesareconstructedfollowingtherecommendationsofIEC120.The

differentpiecesdonothavesharpedgesorpointsthatcancausecoronaandradiointerference.

Partsincontactwiththecablesaredesignedandmachinedtoavoiddamage.Thecontactsurfaces

betweenthevarioussuccessivepiecesaredesignedtofacilitatetheflowofcurrentsofhighshort

circuit.

Allferrouspartsotherthanstainlesssteelarehotdipgalvanized.Galvanizingcomplieswiththe

requirementsofASTMandespeciallytothefollowingstandards:A123,A153andA239.

Galvanizingmustresistto7immersions(5threadedparts),of1minuteeach,inasolutionofcopper

sulphateat20C,accordingtothestandardA239.

7.2

Applicable

Codes

and

Standards

IEC120Dimensionsofplebeianassembliesandsocketelementsinsulatorstring.

7.3Reinforcementofprotection

Thepurposeofreinforcementofprotectionistwofold:

1)itismainlytoremovethepowerarcfarenoughinsulatorsandfixinghardwaredriverstoensure

thatthesepartsaredamaged,

2)itensuresamorefavorabledistributionoftensionbetweentheinsulatorsandopposethe

formationofscentonthechainortodiminishtheimportancetomaintainanacceptablelevelof

interference.

All161kVinsulatorstringsarefittedwithguard(spark)atbothendsseparatedbyabout1500mm,

correspondingtoanominalvoltageoflightningimpulsewithstandof750kVaccordingtoIEC71.

Thesecarearrangementsaremade,massside,bythehornsanddriver'sside,bysnowshoesoropen

ringswithball.Hornsandsnowshoesareroundsteelofdiameter18mmandaminimumdistance

betweenthetipandtheedgeoftheskirtclosestinsulatorisnotlessthan200mm.Theyare

arrangedinaplanenormaltothedriverandarrangedontheoppositesideoftheinsulatortothe

shaftofthepylon.Anchorchainspylonsstoplocatedinfrontofthepostsareequippedwithspark

gapstovaryingdistancetopreciselyadjustthewithstandvoltagewithstandvoltageto550kVto

protectequipmentagainstvoltagesurgesand325kVforholdingshorttermindustrialpower.

LGplansSS019andSS020LGdefinethevariousinsulatorstringsforuseon161kVlines.

TheplandefinesSSLG021chainsinsulatorsforcablesinsulatedguards.Anchordetailsareshownon

theplans.

7.4Spareconnectingchainstotheframe

Anchorbrackets:


33/44

Theyarepinscreedsthatcanadaptdirectlytothetowersandtoaverticaloscillationoftheinsulator

string.

Suspensionbrackets:

Theseareeither(forvoltageslessthan161kV)fixingbracketswhichthefixingplaneistransverseto

theaxis

of

the

line

so

as

to

allow

the

oscillation

of

the

insulator

string

while

avoiding

rubbing

always

inthesameplace,or(forvoltagesabove161kV)ofthetrunnioncapsthathavetheadvantageof

avoidingtheirdoublearticulation,inflectionsthatappearinthestirrupwhenlongitudinalforces

associatedwiththeruptureofaconductor.

7.5Suspensionclamps

thesuspensionclampsareoftheslipper.Itisprovidedwithajointattheconductorallowing

freedomofmaximumoscillation.

Theyareconstructedofaluminumalloyatleastasregardsthepartsincontactwiththedriverand

providedforcablewitharmorrods.

7.6Armorrods

Inordertostrengthenthephaseconductorandtheshieldwiresateachsuspensionclamp,agasket

twistedsonofthesamealloyasusedintheconductorisinsertedbetweentheconductorandthe

suspensionclamp.

Thisseal(orarmorrods)ispreformedtype,allowinginstallationwithoutspecialtools.

7.7Sleevesanchorandjunction

Theanchorsleevesandjunctionareofthe"compression".Theymustholdthecableinthemost

restrictiveoftwoconditions:95%ofitsratedloadofruptureor2.5timesthemaximumworking

voltage.

7.8Vibrationdampers

Inordertolimitthevibrationsoflowamplitudecables,typeshockabsorbers

"Stockbridge"areinstalledonallconductorsandwires.Attachmentisdesignedtopreventslippage

oncableswithoutleadingtoastrainorinjuryofthelatter.

Thenumberandcharacteristicsofthedamperstobeinstalledandtheirlocationsonthecablesis

calculatedbasedoncabletypeandcharacteristicsofthereach.

7.9Counterweight

exceptionally,counterweightscanbeattachedundertheclampssuspensiontowersalignmentwhosescopeisinsufficientweight.Themaximumweighttobeplacedislimitedto320kg.The

counterweightsaremadeofslabswithamaximumdiameterof450mmandamaximumheightof

500mm.Thefasteningsystemisdesignedsoasnottopreventorlimittherotationofthe

suspensionclamparounditsaxis.

7.10Markingair


34/44

thefollowingprovisionsshallbemadeinareasdeemedhazardoustoairnavigation:riversorriver

crossings,crossingvalleys,approachingairportsandairfields.

Itwillbespheresoftaggingaminimumdiameterof500mmprovidedwithholestoallowtheflowof

water.Thesetransactionsmustbereinforcedpolyesterglassfiberorasyntheticmaterialapproved

bytheClient.Theassemblyofthesesphereswillbesimplewithoutthreadingthecabletaut,and

equippedwith

armor

rods.

Thecolorsoftags(redandwhite)willcomplywithRecommendations

International,aswellastheConventiononInternationalCivilAviation.

8.GROUNDING

8.1Groundingtheshieldwires

Withtheexceptionofshieldwiresusedforruralelectrificationwhichareobviouslyisolated,the

shieldwireareelectricallyconnectedtothemetalframeofalltowersbyastrapandcontactparts

adapted.Thestrapsaremadeofasteelcableidenticaltotheconductor.

8.2Groundingoftowers

Thetowersareconnectedtogroundpotentialthroughthemetalpartofthefoundationsof

prolongedelectricallybycopperfoilof50mm2minimum.Ifnecessary,groundstakesor,ifsoilsare

toohard,catchradialstrip,areusedtoreduceearthresistance.

Inthecaseoftowerslocatedwithin100mofavillage,astriporringofcablewillbeplacedat1m

andfoundationstoadepthof0.5mtoreducetensionandnottocontactincaseshortcircuit.

ThepossibleconfigurationsaredefinedontheLGSS022andtheconnectiondetailsareshownon

theLG023SS.

8.3Connectiontotheconductorisolated

Distributiontransformersforelectricpowersupplyofthevillagesareconnectedtotheshieldwires

insulatedbyairlink.Inthisuse,aspecificpartisfixedtothepylonwasbelowtheupperbracketsto

allowtheanchoringofthefirstrangeof34.5kVcables.Thisscopeisassmallaspossible(30to50m)

sothattheeffortsofthetowerarenegligible.

AprincipleoftheconnectionisgivenontheLG013SS.

9.FOUNDATIONS

9.1General

MostofthetowersusedbytheCEBisthetypewiremesh,foundationsareseparatefeet,exceptin

areasofveryroughterrainwherefoundationsareslablike.

Thechoiceoffoundationsreflectsthenatureofthesoilandtheimportanceofsolicitationsthatare

appliedtothesefoundations.Ifthelandisofgoodquality(asisusuallythecaseinBeninandTogo)

toaconcretefoundationslabandchimneyareused.Ifthelandisofpoorquality,deepfoundation

pileorslabtypesareused.Note:metalfoundationsthatleadtodramaticallyincreasetheimportof


35/44

steelstructureshavenotbeenretained.

Inthecasewherethesoilissufficientlycoherentandeffortsarenottoohigh,chimneysand

foundationstoslabcanbereplacedwithdrilledcylindricalfoundation.Afterdrilling,thebasisofthe

latterisextendedusingatemplatewhichcanimprovetheembeddingofthefoundationinthefield.

Theupper

part

of

the

foundation

blocks

beyond

the

ground

level

of

0.30

m

in

normal

ground

and

in

groundfloodof0.50metersabovethewaterlevelexpected.Itendedwithadiamondtiptoavoid

stagnationofwaterontopofthemountain,andcoveredwithabituminouspaint.

Thecalculationofmassallowsforapossiblegroundelevationof10%.Beyondaspecialcalculationis

doneforeachparticularcase.

9.2Typesofmassive

foreachtypeoftower,fourtypesofsolidcovermostcasesencounteredinthefield:

Goodsoilwithoutwater,itissoftrock,laterite,clay,sandyclay,shale,

Middlegroundwithoutwater,itisconsistentland,marl,clay,weaklyalteredrocks,

Poorlandorlandunderwater,itissaturatedsoftclay,vases,peat,

Rockyterrain,itishardrock,thelateritic.

Theclumpsarecalculatedfortheconfigurationofthetowerthemostrestrictive(whateverits

height)sothatitcanbeusedforallpossibleconfigurations.

ThedifferenttypesofsolidstandardaredefinedintermsofSSLG026.

9.3Calculationsoffoundations

9.3.1Calculationoftheextractionforce

Ingeneralthecalculationusesthemethodcalledtheangleofelevation.Itconsistsofdetermining

theholdingforceofasolidbytakingintoaccount,besidestheweightofthemassiveweightofthe

landraisedbytheslab.Itisconsideredthattheraisedlandsisatruncatedpyramidwhosesidefaces

formananglewiththeverticaldependentonthequalityoftheground.Thisangleiszeroforbad

land,about30innormalgroundandcanreach70totherock.

Anestimateoftheanglesofelevationthatmaybeencounteredisgivenbythesurveysalongthe

line.Byconsduringtheconstructionofalinetestisperformedateachlocationtodeterminethe

pylontipresistanceandsidefrictiontoaminimumdepthof2.5timesthewidthofthefoundation

belowthelevelofseatofthefoundation.

Theangleofelevationtobeconsideredinthecalculationsisasfollows:

Friction angle inland after soil

testLifting angle to take into account

Less than or equal to 15 0


36/44

Between 15 and 20 10

Above 20 15

9.3.2Calculationofthecompressionforce

The

compression

force

applied

on

the

field

is

the

sum

of

the

following

efforts:

forcetransmittedbythebaseinthecaseconsidered,

weightoftheconcrete,

weightoflandlocatedabovetheslab.

Thiscompressivestressmustnotdriveundertheslabatapressuregreaterthanthemaximum

allowablepressureoftheground.

9.3.3Calculationofthechimney

Itisacceptedthatcurrentfield,theshearforceappliedtothesolidisabsorbedbythereactionof

thesurroundingsoil.Theabovegroundpartofthechimneysisconsideredaconsolebuiltintothe

groundandsubjectedtoabendingforce.Forheightsabovegroundinexcessof0.70m,theconcrete

ofthechimneymustbearmed.

Ifnecessarytoensureproperdistributioneffortsontheslabandavoidworkingconcreteintension,

thefoundationisarmed.

10.CONSTRUCTION

10.1Introduction

Constructionincludesthefollowingmainphases:

repiquetagetheline,

deforestationandslashing,

preparationofaccessroadsandtheirmaintenance,

soiltests,

thefullrealizationoffoundations,includinggroundedandmeasurementofearthresistanceof

towers,

mountingmasts,

thedroulages,prints,clipupandadjustmentofthecables,

theintroductionofvibrationdampingandmarkupspheres,

cleanupsite,


37/44

prescribesuchformsofcontrol,

thevarioustestsandreceiving.

10.2Repiquetage

Topographicalwork

Longitudinal

profile

Theworksconsistoftopographicrecognitionofdrawingthelineonthegroundinthepresenceof

theClientwhicharemarkedthepreliminarylayout,themainobstaclestoavoidandwherethe

definitionisgivenoftheprinciplestobeobserved.Markupofdrawingthelinewithrealizationof

theangularisthenmadeandthenafterapproval,weproceedtofieldsurveythelongitudinal

profileoftheline.Thescalesusedareasfollows:

Horizontalscale:1:2500

Verticalscale:1:500

A

point

is

raised

every

50

m

at

a

minimum,

the

point

density

is

increased

if

required

by

the

field.

Anexampleofverticalalignmentstandardisgivenattheendofthischapter.

Locationofpylons

Repiquetagephaseistoreviewandupdatethelongitudinalprofile(usuallymadeavailabletothe

ContractorbytheClient),thenafterapprovaloffinalprofilesalongwiththelocationoftowers,to

carryrepiquetageinlineandthedefinitivelocationofalltowers.

Thetowersarelocatedonthegroundbymeansofnumberedwoodenstakes,astakeinthe

centeryellowandtworedstakesindicatebothdirectionsoftheline.

Inthecaseoflatticetowers,isperformingthesurveycrosssectionsoflandtothetowersite

locatedonaslopeinordertodeterminetheexactlengthsofunevenfeet.Thesegradientsare

giveninthefinalbookpicket.

Anexampleofstandardpicketbookisgivenattheendofthechapter.

10.3TreeandBrushRemoval

Thewidthoftheinfluenceofdeforestationontheline,26meterseithersideoftheaxisofthe

lineisestablishedforeachstafffollowingtheindicationsontheLG027SS.Itisthendemarcated

onthegroundwithredflagsplacedevery25mfromtheaxisofthelineislocated.

Deforestationitselfconsistsoffellingandstumpremovaloftreesandundergrowthandclearingtheentirewidthofthewaydefinedabove.Thisdeforestationcanbedoneintwoways:

Cuttingandstumpremovaloftreesafterpruning,thebranchesandtrunksbeingstoredalongthe

way,

clearingbybulldozer,inthiscasethebranchesandtrunksarestoredalongthegripwhilethe

stemisremovedandtheholesinthegroundfilled,andleveled.


38/44

Beyondthetrenchslaughter,andeverytreewhoseheightis2m+equaltothedistancebetween

thetreeandtheverticalplanepassingthroughthedrivernearesttobeslaughtered.

Deforestationisdoneearlyenoughtoallowafinalinspectionofthelineprofileandanormal

cable.

10.4Identification

of

damage

Tomarkthefinalinspectionoftheverticalalignment,anexhaustiveandcontradictorydamageto

crops(perennialandseasonal)andconstructionwillbemadetowardscompensatingowners.

10.5Accesstracks

Thisworkaretocreateanaccesstrackatdifferentlongitudinallineofpylonsandaccesstracks

crosstoquicklyexploredifferentpointsofthelinefrommainroads.Thesetracksareproperly

gradedandhavealateralclearanceofvegetationsufficient.

Accesstrackscrossaresignpostedfromthemainroadwithsignsmarksofatleast1.0x0.5mand

are

shown

on

the

longitudinal

profile.

Thegeneralcharacteristicsofthetracksare:

!Trackwidth:3m.

!Accessiblebyallterrainvehiclesevenintherainyseason.

!Equippedwithlightstructurescrossingseasonalstreams(riffles,gabions,bridges,culverts

buriedwithheadprotectionnozzles).

Thebasicprinciplesofimplementationare:

A Tracks

1.Scouring

"Depth:(050cm),strippingoftopsoil

"Width:sufficienttoobtainatreadof3m.

2.Profilinganddrainage

Performinglongitudinalditcheswithgrader.

Divergentperformanceofditchesandoutfalls.

Formofslopeofatleast2%.

3.Embankmentandreloading

difficultpassages

!floodplains

!Accesscrossings

Areaswithhighexcavation

Crossingofexistingrunways


39/44

4.excavated

Easeslopesgreaterthan10%.

B Structures

submersibleraft

Gabionsandriprap

Culvertsabutmentswithprotection

Nozzlesraftwithheadprotection

Roadalignmentswillbedeterminedasfollows:

Thetransitionfromonepylontoanotheriscarriedoutpreferablyinastraightlinealongtheline

orreturningbyashortantennatotheslopesandexistingstructures.

Theroutewillbeestablishedinadvance,duringavisitcontradictory.Someminorchangescould

bemadelaterbasedonexperiencegainedduringthework.

10.6Foundations

10.6.1Recognitionofsoil

Ateachlocationofthepylon,apenetrationtestisperformedsoastodetermineresistancetothe

tipandthelateralfrictiontoaminimumdepthof2.5timesthewidthofthefoundationbelowthe

levelplannedfoundationarea.

Incaseswherethesoildoesnotperformthistypeoftest,apressuremetertestisperformed.

10.6.2Selectionoffoundations

Foundationsareselectedonthebasisoftestresultsofsoilandfoundationtypesdefinedinthe

precedingparagraph.

Inplaceswhere,giventhepredetermineddifferentialsettlement,thelandisnotconsidered

strongenoughtotreadonafoundation,afoundationslabisusedtoboundfeet.

10.6.3Execution

Excavationoffoundationsforstructuresareperformedwiththedimensionsshownontheplans

offoundations.Ifnecessary,temporaryconfortementswallsoftheexcavationareintroducedand

removedasandwhenconcreting.Searchfundsaremaintainedinthestateofnaturalterrain,

perfectlytunedtorelativelevelsandoverallcorrectbecausethefoundationcanonlybebasedon

fillmaterial.

Afteropeningthesoilexcavationtoexcavationbottomischeckedandthepresenceofabodyofwatertotakeallnecessarydecisionsincaseofdeviationsfromtheassumptions.

Ingoodgroundrunningsearchesaugerisrecommended.

MarkupSecurity

Securitymarkupwillbeinstalledaroundtheexcavationbeforebackfilling.


40/44

SummitFoundation

TheSummitFoundationislocated30cmabovethenaturalgroundandfinishedindiamondto

avoidwaterstagnation.Infloodproneareas,topsoffoundationsislocated30cmabovethe

highestwaterlevelsothatthemetalpartsareneversubmerged.

10.7Implementationofthebasesoftowers

Attentionisdrawntotheneedforestablishingstableandhighlyaccuratefoundationsandpylons

feetinalldirections,observingthedistances,angles,orientations,andrelativelevelsofalllevels.

Theseprecautionsarenecessarytoavoidintroducingimbalancesinthedistributionofeffort

betweenchordsordiagonals,orineligibletosecondaryefforts.

Thetrenchbottomshouldbecoveredwith10cmofstabilizedsand(composedof100kgof

cementperm3ofsand),perfectlylevelinordertointroducetheverticalflangesoftheanglesand

obtainacorrectsurface.Thedepthoftheexcavationshallbeadjustedaccordingly.

The

setting

of

the

bases

must

be

by

an

approved

method

(using

templates

or

theodolites).

The

permissibletolerancesonthepositioningofthepylonandthesettingofthebasesare:

Positioningtolerancesofthepylon

longitudinaldeviation:lessthan50cm

gaptransversetotheaxisoftheline:(D/500+5cm),Dbeingthedistanceinmetersofthepoint

consideredatthepointofclosestangle.

verticaldistance:3mmpermeter

Tolerancesinthesettingofthesockets

thedistancebetweenthetopofthebasesandtherealaxisalignmentmustnotexceed5mmper

meterwithamaximumof50mm.Angleforthetowers,(typeBandC),thesedistancesare

measuredfromtheinternalbisectoroftheangleoftheline.

thedistancesbetweenthetopsofthebasesshouldnotbedifferentfromthevaluesshownon

theplansofmakingmorethan0.5mmpermeterwithamaximumof

10mm.

Thegapontopofthediagonalsofthebasesmustbelessthan1mmpermeter,withamaximum

of20mm.

Thedifferenceintheinclinationofthebasesmustbelessthan3mmpermeter(0.3percent).

Thedistancebetweenthetheoreticalcentralpoint(step)ofthepylonandthepointof

intersectionofthediagonalsmustbelessthan2mmpermeterdiagonal,withamaximumof50

mm.

Thetopofthebasesmustbeinthesameplane.Themaximumdifferenceinlevelbetweentwo

basesmustnotexceed5mm.


41/44


42/44

Thisoperationincludesatleast:

triagerooms,

verificationthatthepartsprovidedwiththeassemblies,

transportmountingsites,

assembly,

cleaningandmountingthepylons.

Thepulleysforthedrawcablesareinstalledatthattime.

10.12Drawandcontrolcables

Thisoperationincludesatleast:

Transportsitesdrawingofcabledrums,toolsandaccessories,

Theinstallationofprotectivetemplatescrossingsofrailways,roads,etc..,

Unrollingundertension,circulationandcableadjustments,

Makingjoints,anchorclampsandstraps,

Runningdownhillontheporchesoftransformerstations,

Theestablishmentofvariousaccessories(armorrods,vibrationdampers,spheresmarkup,

spacersetc..)

Thereturnofsurplusequipment,cleaningtheyardandrehabilitationplaces.

10.12.1Drawingcables

Protectiondrumsduringstorage,handlingandtransportissuchthatatthetimeofthedraw,the

reelsshownodamageandnodamagecables.

Theinstallationofgatestoprotectpassingoverhouses,roads,linesHT,MTorBTandother

obstaclesispartofthework.

Thecablepullingandpeelingarecarriedoutundermechanicaltensionbymeansofawinchanda

braketherebytensioningthecableandensuresthatthedriverdoesnottouchthegroundandnotlikelytobeinjuredbycontactwithsharpedges.

Thecablesarebased,tosupport,onpulleyswithballbearingdesignacceptabletoavoid

damagingthecable.Theeffectivediameterisatleast20timesthediameterofthecabletothe

phaseconductorandtheconductor.Alternatively,ifaseriesofpulleyssmallerisused,theymust

bearrangedsothatthecableisbasedonaradiusequaltoatleast20timesthediameterofthe

conductor.Blockhooksmustbeofuniformlengthsothattheconductorsareheldatauniform


43/44

distance,notmorethan500mmaboveorbelowtheirfinalpositionwhenhung.

Thecablevoltageattheoutputofreelscannotexceedthevaluespecifiedbythecablesupplier.

Thisvaluemustbecontrollablebythepermanentindicationbrakeman.

Unlesstheyareclampedonthecableendstosacrifice,theclampsaredrawingtypejawand

parallelcontact

surfaces

smooth,

ripple

free

and

are

of

proper

length

to

ensure

the

power

cable

withoutbending,notchorslippingofthecablestrandsandwithoutrelativeslidingofthesteel

coreimpregnatedwithgrease.

Thecablesarenotraisedwithtoolstosmallradiusofcurvatureorlikelytocauseinjury,the

curvatureofthecontactsurfaceisatleastequaltothatimposedaboveforthepulleys.

Anyportionofacablewithanyinjuryiseliminated.Thecablelengthsrejectedwithalengthless

than150mwillnotbeusedinfullonline.However,theycanuseinthemanufactureof

suspenders.

Duringpullingoperationsandadjustment,thecablesaregroundedtoavoidanyaccidentby

lightning.

10.12.2Manufactureofgasketsandclampsto

Jointsandclampstocompressiontypearemadeaccordingtothemanufacturer'sinstructions

andtoensure,firstly,theelectricalconductivitywarrantyandsecondly,amechanicalstrengthof

tensionmembersatleast95%ofthetheoreticalfailureofcablesonwhichtheyareinstalled.

Thecableendsarethoroughlycleanedbeforeintroductionintothejointsorclampsandinclude

cleanedoffat.Tocompressthesleevesarefilledwithspecialpaste,accordingtothe

manufacturer'sinstructions.

Aftercompression,theanchorclampsandjointsshouldbeasstraightaspossible.

Thejointsurfacesbetweenthelegoftheclampbodyandtheneckanchordeathmustbeclean

andflat.Tothisend,thetwocontactsurfacesarebrushedinordertoremovethealuminalayer

andcoatedwithgreaseorpasteappropriatecontactadvisedbyfittingmanufacturer.

Outsideendsofthelengthsonreels,theuseofsealsis,inprincipleavoided.Thereisnomore

thanonecableattachedto3litters,orattachedtolessthan15mfromthenearestclip.Thereare

nojointsinthecrossingsofroads,railways,lake,river,etc...

Intheeventofcabledamage,theContractorshallsubmitarepairmethodto

Maitred'Oeuvre:normalsealorrepair,orcutsomelengthsofcables.

10.12.3Trimmingcables

TheadjustmentisdoneseparatelyforeachTownshipposes,definedbybracketswithchain

anchor.Intermediateadjustmentsaremadewheneverthehorizontalcomponentofthevoltage

cannotbeguaranteedduetofrictioninthepulleysandthelargenumberoflittersorunevenness.

Drawingoperationsundermechanicaltensionandsettingareconductedsothatthetowersare

neveroverloaded.Tothisend,itbelongstotheContractortobringallnecessaryinformation,


44/44

especiallythetablesofmaximumpermissibleeffortsandsupportfortheloadcasesconsidered.

TheContractormayberequiredtostakeoutsomemediaconsolesormedianotintendedfor

loadcasesencounteredduringinstallation.Thistypeofoperationmustbekepttoaminimum.

Moreover,thevoltageappliedtothecablesmustnotexceedthemaximumvoltageshowninthe

tablesaslayingthecableissubjectedtophenomenasuchascreepundertheeffectofstressitis

submittedafter

installation.

Ineachsetting,driversaretreatedasuniformlyaspossibletowhattheylaterthesamecreep.To

thisend,we'applytoacompletesetinthes

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