Study Committee B2 Technical Advisory Group B2-AG-06 2011/Brian - New Conductor use Tutorial in... · Scope LookattherangeofnewbareconductortypesLook at the range of new bare conductor

Study Committee B2Technical Advisory Group B2-AG-06

Cigré AG06 Seminar Bangkok

Types and Uses of High Temperature Conductors

Brian WareingBrian Wareing.Tech LtdgChester, UKConvenor Cigré AG06 WG48 ‘Experience with the Mechanical Performance of New Conductor types’Performance of New Conductor typesSecretary Cigré AG07 WG28 ‘Weather effects on Overhead Lines’

ScopeLook at the range of new bare conductor typesLook at the range of new bare conductor types availableAppreciate new conductor characteristics and suitability in comparison with standard conductor typesMake you aware of the requirements whenMake you aware of the requirements when choosing conductorsCovers construction, design and operationg pSee how network up-grading problems can be solved cost-effectively by conductor choice

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Types and uses of High Temperature

Conductors3

Basic Types

Cigré has categorised new conductors inCigré has categorised new conductors in four basic types

Type 1. Conductors composed of a steel core and yp pan envelope for which the high temperature effects are controlled by means of thermal-resistant aluminium alloys (e g GAP TAL HACIN)resistant aluminium alloys (e.g. GAP, TAL HACIN)Type 2. Conductors composed of a steel core and an envelope for which the high temperature effects are controlled by means of annealed aluminium or aluminium alloy (e.g. ACSS)

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Conductors4

Basic Types

New conductor typesType 3. Conductors composed of a non-metallic core,

d l f hi h th hi h t tand an envelope for which the high temperature effects are controlled by means of thermal resistant aluminium alloys (e.g. ACCR)y ( g )Type 4. Conductors composed of a non-metallic core, and an envelope for which the high temperature effects are controlled by means of annealedeffects are controlled by means of annealedaluminium or aluminium alloys (e.g. ACCC)

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Conductors5

Basic Structure of traditional bare wire conductors

AAAC, AAC, ACAR, Copper

ACSR

Compacted ACSR

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AluminiumStandard Aluminium and Aluminium Alloys can only operateStandard Aluminium and Aluminium Alloys can only operate continuously at temperatures up to 93ºC without causing metallurgical decay resulting in lifetime reductionTAL and ZTAL aluminium have essentially the same conductivityTAL and ZTAL aluminium have essentially the same conductivity and tensile strength as ordinary electrical conductor grade aluminium but can operate continuously at temperatures up to 150ºC and 210ºC, respectively, without any loss of tensile strength150 C and 210 C, respectively, without any loss of tensile strength over time. Fully annealed aluminium is chemically identical to ordinary hard drawn aluminium and can operate indefinitely at temperatures atdrawn aluminium and can operate indefinitely at temperatures at 250ºC (and higher) without any change in mechanical or electrical properties but has a much reduced tensile strength.

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Conductors7

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Core Material

Galvanised steel is the normal core material for standard ACSR conductors. This is subject to corrosion and potential failure when the galvanising has disappearedpotential failure when the galvanising has disappearedHigh Tensile steel is used when stronger conductors with less sag are requiredg qInvar steel is used for low sag because of its very low thermal expansion coefficientHi h t th l d ti it l i i ll bHigh strength, low conductivity aluminium alloy can be used as a core material to give improved strength to AAAC conductors.

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Conductors9

Steel aluminium or composite coresSteel, aluminium or composite cores

A conductive core will take part of the AC current and heat up

Steel can sag more due to heatingCeramic fibre reinforced aluminium can be stressed under thermal cycling due to mis matchstressed under thermal cycling due to mis-match in expansion coefficientsPure composite core will not take significant p gcurrent

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Conductors10

4.5

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Conductors11

High temperature conductor types

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Conductors12

High Temperature ConductorsHigh Temperature Conductors

“High Temperature Conductor” is defined as a conductorHigh Temperature Conductor is defined as a conductor that is designed for applications where continuous operation is above 100°C or the conductor is designed to operate in emergency conditions above 150°Coperate in emergency conditions above 150 C.In fact some can be run at over 200°C continuously and over 220°C for short times.This gives us spare capacity or ‘redundancy’ in the network for future expansionTo take advantage of the high temperatures (and soTo take advantage of the high temperatures (and so Ampacities) low sag is also required and this uses the technique of the ‘Knee point’

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Conductors13

Knee PointOccurs for all ACSR type conductors when the tensile load is transferred from the (high expansion coefficient) aluminium to the (low expansion coefficient) core)This produces a change of angle in a sag/temperature graphThe point at which this occurs is known as the ‘Knee point’

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Conductors14

15

14Original 400 mm2 Zebra ACSR

26.5 kN @10 0C560 mm2 ZTACIR

38 kN @ 10 0C

12

13

rd L

2 Sp

an, m

Original design maximum sag,

1950s

11

366

m S

tand

ar

620 mm2 Matthew GZTACSR38 kN @ 10 0C

9

10

Sag

of

570 mm2 Sorbus AAAC36.9 kN @ 10 0C

Knee points

80 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200

C d t T t 0C

@

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Conductors15

Conductor Temperature, 0C

New Conductor 3MConductor Types

3MACCR

Lumpi HACINLumpi HACINACSS

CTC ACCC

J-PowerG

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Conductors16 16

Gap

Type 1- J-Power Gap

1. High Temperature aluminium alloy2. Inner layer forms a tube containing

free moving high tensile steel core in greasefree moving high tensile steel core in grease1. Very low vibration levels2. Used world wide

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Conductors17 17

2. Used world wide

Pros and Cons - Gap

Low vibration levelsKnee point at erection

Cannot be joinedSpecial fittingsp

temperature*Long history of use

p gGrease can dissociateSag relies on steel coreCan be noisy

* Erection temperature can be 5ºC in UK, 50ºC in Middle East, 30ºC in SE Asia

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Conductors18

All this affects the final sag!

Type 1 - Lumpi-Berndorf HACINType 1 Lumpi Berndorf HACIN

High Temperature Zirconium Aluminium alloyAluminium coated Invar steel core – no corrosionU t d d ACSR fittiUses standard ACSR fittingsHigh ampacityUsed by NIE in UK

Galvanised steel Salt spray testACS

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Conductors19 19

Used by NIE in UK

Pros and Cons – ZTAL/HACIN

Uses standard fittingsCan be joined

Higher knee point than Gap (~50°C)Can be joined

ACS has long history of use in OPGW

p ( )High strength low sag Invar Steel core can be expensiveCan be treated as

conventional ACSRAluminium coating avoids

expensive

Aluminium coating avoids corrosionInvar use gives low sag

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Conductors20

Type 2 - ACSSACSS can be stranded using

Annealed Aluminium

ACSS can be stranded using either round or trapezoidal shaped annealed aluminium wires. In either design, the conductor depends primarily on the steel St ldepends primarily on the steel core wires for mechanical strength.

Steel core

This core may be aluminised, galvanised, zinc-5%aluminium Mischmetal coated or aluminiumMischmetal coated or aluminium clad steel

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Conductors21

Pros and Cons - ACSSSoft al mini mTW means smaller

cross-section and so

Soft aluminium requires care in handlinglower wind loads

Can be joined

handlingHigher knee point than Gap

Sag determined by steel

than GapPure Aluminium has lower strength than

High conductivityUsed in USA

galloyCan suffer corrosion

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Type 3 - 3M ACCRyp

Al i i t iAluminium matrix coreVery strongN t lNo steelHigh temperature aluminium alloyE i

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Conductors23 23

Expensive

Pros and Cons - ACCRPros and Cons ACCR

No steel so no corrosionCore as strong as steel

High knee point (~70°C)Can creep

High temperature operation (>200ºC)Core lower expansion

Expensive

Core lower expansion coefficient than steelLow kg/m

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Conductors24

Type 4 - CTC ACCCyp

C b fib ( t d li ht th t l)Carbon fibre core (stronger and lighter than steel)High temperature, high conductivity aluminiumCan operate up to 250°CCan operate up to 250 CLow tension so less stress on structuresVery low sags

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Conductors25 25

y gInstalled in several countries

Pros and Cons - ACCCPros and Cons ACCC

Extremely strongExtremely strong composite core (50% stronger than steel)

Special fittingsSoft aluminium requires

i h dliVirtually no increase in sag above knee pointHigh conductivity alloy

care in handlingMinimum bending radius for coreHigh conductivity alloy

Can be used up to very high temperatures

for core

g pUsed world-wideVery low kg/m

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Conductors26

Fittings

Most new conductor types require special fittingsAn exception is the ZTAL/HACIN ACSR which can use

i ti ti l fittiexisting conventional fittingsThese fittings may run hotter than normal and so may incur some overheating unless specifically designed forincur some overheating unless specifically designed for high temperature operationBut commonly many HT conductors are run at <100ºC in

l ti fitti l h t ith t d hi hnormal operation so fittings only have to withstand high temperatures for short periods

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Conductors27

Conductor range

The new conductor types are mainly aimed at tower lines Th f thi i th t th i i iThe reason for this is that there is a minimum size that trapezoidal stranded conductors can be mademadeHowever, these conductors can be used on wood pole lines and some (e.g. ACCC) are in use on 33kV networks in USA and UK (HACIN is due to be erected in Oman at 33kV).

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Conductors28

EconomicsEconomics

New conductors are expensive – between 3 and 6 times more than conventional conductors but it is generally towers that are expensive and conductor costs <10% ofexpensive and conductor costs <10% of overall line costs.So is doubling of power capacity worth a 20%So is doubling of power capacity worth a 20% increase in line cost? Generally yes!However many HT conductors are run atHowever, many HT conductors are run at <100ºC in normal operation (N-1 basis) and this reduces I²R losses

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Conductors29

Economic re conductoringEconomic re-conductoring

In the UK, re-conductoring 132kV wood pole lines with Poplar (200mm² AAAC) and tower lines with Sycamore (250mm² AAAC) size equivalent HT conductors should(250mm² AAAC) size equivalent HT conductors should need no tower strengthening so reduce overall costs.Typically, CTC ACCC Casablanca can give an 80% yp y gampacity gain (when restricted to 150ºC) and Lumpi-Berndorf ‘s 194TAL/HACIN a 50% increase in ampacity compared with Poplar at 75ºCcompared with Poplar at 75 C

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For new lines the sag limitation imposed by Poplar will not be

New BuildFor new lines the sag limitation imposed by Poplar will not be present. So in terms of ampacity only, without taking into account sags, the best performing conductors on a UK P27

ti t 150ºCsummer rating at 150ºC were

CTC ACCC Amsterdam with 110% increase

3M ACCR 575-T23, CTC ACCC Oslo and Lumpi-Berndorf 294TAL with around a 90% increase294TAL with around a 90% increase

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Conductors

Uses of new conductorsUses of new conductorsThe optimum use of new conductors depends on the

bl ith t t k d th l lproblems with current networks and the local environment

Polluted areasPolluted areasHigh ambient temperaturesIce prone areasIce prone areasNon-icing areasSag problemsSag problemsSpan lengths

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Conductors32

Network RequirementsAffordable re conductoring or new buildAffordable re-conductoring or new-buildEfficient (low loss) conductor High capacityHigh capacityLow SagRunning cold – a conductor that delivers high ampacity at a lower temperature has

Lower line lossesLonger fitting lifeLess chance of breaking regulatory clearances

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Conductors33

Polluted areas

Need to choose a conductor which does not have an unprotected steel core that is likely to corrode e.g.

C i d dComposite cored conductorsAluminium coated steel coresGap has a steel core in a grease layer so will not corrode if grease stays

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Conductors34

High ambient temperaturesHigh ambient temperatures

Need to have a conductor that can operate at well above ambient temperature to get high power capacity e.g.

HT d i h l d l i iHT conductors with annealed aluminium can operate continuously at up to 250ºCZTAL t t 200ºCZTAL can operate up to 200ºC

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Conductors35

Ice prone areas

Heavy ice loads can cause excessive sagsSome conductors can have customised cores for heavy ice load areasACCC has the option of high pre-tension so that nearly all the load falls on the extra strong core

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Conductors36

Small sag at high ampacitySmall sag at high ampacity

Main emphasis here is on electrical low sag performance which requires high ampacity and low expansion coefficient of the core e gcoefficient of the core e.g.

The carbon fibre composite core which has lowest electrical sag of all HT conductorslowest electrical sag of all HT conductorsInvar steel which has a much lower coefficient of thermal expansion than other steelsof thermal expansion than other steels

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Conductors37

Span lengths

Long spans require very strong and low sag conductorsThe strongest conductor by far is that with a carbon fibre composite core which is more than twice as strong as any steel or al mini m matri corealuminium matrix core

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Conductors38

Specific Tensile StrengthConductor strength and weight directly impact the amount of sag (D) and tension (H) in an overhead conductor. SpecificallySpecifically,

D= w*S²/(8*H) where;where;

S=span lengthw= weight per unit length

Th (H/ ) i di tl l t d t ifi t il t thThus (H/w) is directly related to specific tensile strength. Generally the higher the H/w, the less the conductor sags.

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Conductors39

Typical values of H/w for Sycamore equivalent conductors

Sycamore equivalent HT conductors

Conductor UTS (kN) kg/m H/w (kN.m/kg)

Sycamore 85 0.835 101.8

ACCC Oslo 148 0.992 149.2

Gap 265 108 1.098 97.9

HACIN 246 97 1.088 88.9

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Conductors40

ACCR 575‐T23 126 1.037 121.4

SSummaryDescribed the more commonly available High y gtemperature conductorsBriefly given advantages and disadvantages of the four basic typesbasic typesExplained why they can be of benefit even if not required to be run at high temperaturesg pExplained the importance of the knee pointProvided some basic examples of useGAP, ACCC and ZTAL/HACIN currently being field tested in UKHave a read of Cigré TBs 425 and 426Have a read of Cigré TBs 425 and 426

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Conductors

FinallySCB2 AG06 WG48 ill look at ‘E perience ithSCB2 AG06 WG48 will look at ‘Experience with the Mechanical Performance of New Conductor types’typesSCB2 AG07 WG51 under Dale Douglass looks at the electrical aspectsat the electrical aspects

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Conductors42

Documents

Study Committee B2 Technical Advisory Group B2-AG-06 2011/Brian - New Conductor use Tutorial in... · Scope LookattherangeofnewbareconductortypesLook at the range of new bare conductor