TUTORIAL 21.17 – TB 194 - Stichting CIGRE Nederland B1-NL. 194. Construction, Laying and...

Cigré SCB1 – Construction and installation techniques for land cables

TUTORIAL 21.17 – TB 194

Technieken voor constructie, leggen en

installatie van kabelsystemen

Peter van VelzenEngineering

JoulzCigre B1-NL

194

Construction, Laying and Installation techniques

Januari 2012

Working group21.17


Working Group 21.17 members

• J.P.M. ANTONISSEN (The Netherlands),• P. ARGAUT (France),• R. AWAD (Canada),• B. DRUGGE replaced by F. RÜTER (Sweden),• T. FAGERENG (Norway),• M. GENOVESI replaced by F. MAGNANI (Italy),• A. GILLE (Belgium),• P. HUDSON (United Kingdom) (Secretary),• R. JOHNSTON (Australia),• T. KARASAKI replaced by G. KATSUTA and after by T. SASAKI (Japan),• K. LAGERSTEDT (Denmark),• H.S. LEE (South Korea),• Y. MAUGAIN1 (France) (Convenor),• M. PORTILLO (Spain),• T. J. RODENBAUGH (United States),• R. SAMICO (Brazil),• R. SCHROTH (Germany).


TUTORIAL 21.17 – TB 194

Aim of the presentation

• Sharing of knowledge

• Informative

• Could contribute to new developments


Presentation overview

• Introduction• Terminology• How to go from A to B?• Design of a link• Traditional Construction Techniques• Innovative Construction Techniques• Design of a link (sequel)• Cable Installation Design• External Aspects


Introduction

What is a good link ?

Well designed

Well manufactured

Well installed

Well tested

Well maintained


Terminology

• Construction techniques:o Cable route designo Civil works erection

• Installation techniques:o Cable system designo Cable installation methods


How to go from A to B? (1/3)

hill

river

A

bridgesnational park

floodedarea

B

R1C1

L1

L2

L3

L4

L5

C2

C3

C4

C5

C6

C7

R2

R3

R4

R5


Design of a link (1/5) Data collection

• Methodologyo Data collection: Electrical and Soilo Process: Selection of cables, accessories among existing ones

• Designo Cable cross sectiono Earthing methodo Number of cables per phase

• Identification of obstacles to crosso Roads, railways, Rivers, National parks, archaeological sites,

etc.o Thermal and Electrical proximitieso Services, Trees

Division in sections


• In each sectiono Local and National regulations

• Allowed civil work techniques• Allowed time of trench opening• Right in rem• Available civil work techniques

in the countryo Soil

• Stability, Hardness, Resistivity, Seismicity

In each section, possible civil work techniques

Design of a link (2/5) Cable route design


Traditional Construction techniques

Four traditional techniques1. Ducts

o Considered as flexible installationo Mainly used in urban areas

2. Direct burialo Mainly used in rural areaso Economical

3. Micro tunnelso Not accessibleo Usually only one cable circuit

4. Troughso Not applied in Netherlands


Eight innovative techniques

1. Mechanical layingo Simultaneous trenching and laying techniqueo Trench and backfill at the same time : no o Reduction of the size of the trencho High speed: up to 1000 m/dayo Cost efficiento Limits of the technique

• Preferable without other services along the route• Long “train” : 50m • Difficult to take bends

Innovative Construction Techniques (1/7)


2. Dedicated bridgeso Used for special crossings river, railways,

roads, ...o Limits of the technique

• Cost• Temp of the environment: careful study

3. Shaftso Generally used in hydro power plants or to reach deep tunnelso Limits of the technique

• Extruded cable: could need a special cable design to avoid the slip of the different components

• Cable pulling is from top of shaft. Think how to pull the cable.• Safety aspects are important• Moisture and temperature to be considered



4. Horizontal drilling or directional drilling (trenchless technique)

o Drilling a hole for a special crossing, first pilot hole, then widened with a back reamer to the proper dimensions for the conduit

o Used for special crossings river, railways, roads, ...• Installation of ducts inside the hole• No local disturbance such as traffic disruption

o Limits of the technique• Length : depending on the size of the machine. Max=1500 m

o Risks• Damage of other services, No warning



5. Pipe Jacking (trenchless technique)

o Jacking by rotation, pneumatic rocket, thrusto Pushing into the soil prefabricated tubeso Installation of ducts inside the holeo Limits of the technique

• Not applicable in hard soils, not recommended in heterogeneous soils

• Length: 100 m max between two stations• Diameter: max 2.5 m• Need a large working area• Long work duration



6. Embeddingo Excavating the riverbed from a barge or

with remote operated vehicleo Applicable to land and submarine cableso Ducts in the trencho Limits of the technique

• Length of the reel (no joint under water for land cables)

7. Use of existing structureso Cost sharingo Limits of the technique

• Need operation guide with the other utilities• Issues to consider : Magnetic field, fire behaviour, earthing,

induced voltages, heating, impact on other services



8. Multi Purpose Tunnelso Useful technique in busy areas or through mountains

• Higher rating than with cables laid in soilo Limits of the technique

• Air temperature: ventilation may be needed. In some cases, air conditioning and/or water cooling

• Water drainage: water collection is needed

• Work duration: very long• Easy for maintenance




Multi Purpose TunnelsOther infra present:

• N pipelines

• CO2 pipelines

• Petrol pipelines

• Sewer (HP)

Tunnel diameter:

• 4.2 m

Tunnel length:

• 400 m


• In each sectiono Identification of the sizing pointo Checking of the cable design and ampacity

If necessary, modification of:• Cable cross section• Earthing method• Cable architecture

Design of a link (3/5) Checking of cable design


o Site duration, Site working timeo Magnetic fieldo Laying techniqueo Maintenance and repair system, Cable removal

o Construction cost, o Maintenance and repair costo Operation cost, Link non availability cost

Choice of a technique for each section with cost and safety aspects

Design of a link (4/5) Choice of a civil technique


o Laying technique, o Installation technique: rigid or flexibleo Pulling technique, Pulling tension, Sidewall pressureo Drum transportation

o Cable system performance (ampacity and thermomechanicalthrusts)

o Choice of cable, accessories, length on each drumo Final design of cable, civil works, installation

o Workso Final ampacity according to workso Commissioning

Design of a link (5/5) Cable installation


Cable Installation Design (1/3)

• Installation design in the airo Rigid Systems

• No movement due to thermal expansion• Need spaced cleats

o Flexible systems• Free to move horizontal or vertical deflection called snaking

o Cable in ductso No longitudinal expansion or contraction

due to temperature changeo When installed in air, cable temperature

increases more rapidly than in buried conditions (thermal capacity of the surrounding)



• Filled ducts (for example with bentonite): rigid installation [rare]

• Unfilled ductso Large diameter duct (1.5 to 2 times the cable diameter)

• Considered as flexible installation• Snaking inside the duct• Low thrust

o Small diameter duct (< 1.5 times the cable diameter)• Considered as rigid installation • No snaking inside the duct• Important longitudinal cable thrust



• Installation design for buried cableso Backfill

• To improve heat dissipation• Moisture content of backfill is very important• Thermal resistivity of a good backfill is 1.0 K.m/W even in dry

conditions

o Cooling systems (permanent or during high load periods)• To increase the cable ampacity by

• Forced ventilation• Water cooling in ducts laid in parallel. Need cooling stations regularly

spaced


Cable laying

• Clearance in ductso Depends on the route profileo Normally, inner duct Ø ≥ 1.5 external cable

• Pulling tensiono Cable weighto Bend radius

• When pulling the cable:o Need to check the tension withstood by the

conductor

• Side wall pressure


Installation Methods

• Traditional installation methodso Nose pullingo Synchronised power drive rollerso CaterpillarCould be used in conjunctiono Bond pulling

• Mechanical laying

• Laying in tunnel

• Water pullingo Pushing-Floating-Pulling system


External aspects

• Also need to take into account:o Location urban or ruralo Right of way cable system widtho Magnetic fields cable arrangemento Crossing of utilities

• Protection of the o Environment from a system faulto Cable system from a mechanical aggression

• Protection of the workers o During works o During maintenance


Conclusions

• Everyone has his own role to fulfill

• Everyone has his own responsibility and risk

• Make well-considered choices

• Archive the revision documents

• You will be inspired to undertake new techniques


Thank You For Your Attention

TUTORIAL 21.17 – TB 194 - Stichting CIGRE Nederland B1-NL. 194. Construction, Laying and...

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Transcript of TUTORIAL 21.17 – TB 194 - Stichting CIGRE Nederland B1-NL. 194. Construction, Laying and...