construction of transmission and distribution lines imia ... · transmission lines mostly use three...

Construction of Transmission and Distribution Lines

IMIA WGP 69

Annual IMIA Conference Berlin 14th Sep. 2010

The International Association of Engineering Insurers

2IMIA Info

Prepared by: Eric Brault, AXA Corporate Solutions (Chairman)

Ivan Blanco, XL MadridMatia Cazzaniga, ZurichRoland Gmuer, AXA Corporate Solutions Martin Jenne, Munich RePeter Königsberger, UNIQAAlberto Mengotti Forn, Mapfre Erik Poeplow, AXA Corporate Solutions Maurizio Colautti, GeneraliJohn Forder, Willis LondonNiels Kragelund, RSADavid Walters, ACE

Construction of Transmission and Distribution Lines

IMIA WGP 69


3IMIA Info

• Technical description of Transmission and Distribution Lines• Construction process and costs• Information needed and Underwriting views• Pure Insurance Aspects• MPL Considerations• Recommendations• Conclusion

IMIA WGP 69 SUMMARY


4IMIA Info

• An overhead power line is an electric power transmission line suspended by towers or poles

• The line is a transfer item to carry the power from one point to another point. To avoid black out of the power, lines are interconnected, forming a grid.

• Transmitting electricity at high voltage reduces the fraction of energy lost to resistance.

Technical description


5IMIA Info

Transmission lines mostly use three phase alternating current (AC). High-voltage direct current (HVDC) technology is used only for very long distances (typically greater than 400 miles), undersea cables (typically longer than 30 miles) or for connecting two AC networks that are not synchronized.

Technical description• Main components:

• Foundations• Pylons• Insulators and surge arresters• Conductors• Stations with Generating Set up and set down

transformers for substations


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Construction process and costs

Construction Process:• Routing• Foundations• Pylons• Insulators and surge

arresters• Conductors• Fittings• Restoring the site


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Construction process and costs

Costs:• Engineering, choice of the line• Site mobilisation• Civil works construction• Erection of

• Pylons• Insulators and surge arresters• Conductors• Fittings

• Restoring the site and demobilisation

AC line cost

AC terminal cost


8IMIA Info

Comparison of Technique and costs Overhead/tunnelling

Analysis of the Overhead VS Tunneling Power line• Technical trends • Price comparison• Insurance aspects

The nature of the works is different.Equipment is differentPrices are different (Erection VS Construction)Risks are different


9IMIA Info

Comparison of Technique and costs Overhead/tunnellingEXAMPLE

Power line between Flamanville new EPR and grid connection for west of France• Routing • Price comparison• Insurance aspects (standardized steel structure VS

open trenches and tunneling works), self explanatory, natural events/underground risk


10IMIA Info

Information needed and Underwriting views

Underwriter will be concerned in respect of:1. Policy wording scope (perils covered and extensions, including DSU, TPL);2. External hazards;3. Natural hazards;4. Project intrinsic hazards.

Then it is necessary to get information on:• Routing (type of profile, flood prone, mountains, natural hazards exposure

as icing, storm, Third Parties …?)It is important to note that master pylons are mandatory every 5 or 6 km,Then it shall be important to define sections, good order of the line, define a serial loss clause.

• Foundations, (according to ground conditions, groundwater table, interface with external hazards)

• Pylons and electric components (project trends, prices and split up, size, number of conductors, concerned power, substations, transformers…)

• Expected cover requirements, (wordings, extensions, DSU, TPL…)• Business plan• Grid structure


11IMIA Info

Pure Insurance AspectsConstruction Process leads to specific perils and dangers:

• Routing/ design ie: Design risk, natural risk, casualty exposure.• Foundations: Bad concrete, serial loss clause …• Pylons: Pure erection risk, lifting etc…• Insulators and surge arresters: Raw material, manufacturing and

workmanship risk• Conductors: Design, raw material, manufacturing and workmanship risk

Then it is necessary to look at:• For the Design risk, in add to the knowledge of the contractor, (the profile and

location, flood, mountains, icing, wind, vicinity which will increase the difficulty of design and enlarge the exposure of this type of risk). Then define the necessary clauses, as serial loss clause, work in sections, adequate sublimits.

• Foundations, (according to ground conditions, groundwater table)• Pylons and electric components (project trends, prices and split of, size,

number of conductors, concerned power, substations, transformers…)• Expected cover requirements, (wordings, extensions, DSU, TPL…)• For DSU, expected reserve capacity (meaning): Grid reserve, overhead line,

method of expected off-load and back-up. Business plan of the expected operation


12IMIA Info

Pure Insurance Aspects• SECTION 1 Material Damages: Intrinsic

factors• Knowledge of the designer VS location • Concrete exposure (location, access…)• Method of erection (helicopters?)• Buying and specifications for…main

equipment• Project management references

• SECTION 2 TPL : Intrinsic factors• Routing• location choice

• SECTION 3 DSU: Intrinsic factors• Routing/ Design• Foundations• Project scope• Project buffer period• Manufacturer QA

• SECTION 3 DSU: External factors• Grid structure• Location (access)• Manufacturers choice (location)

• SECTION 2 TPL: External factors• Grid structure• Location (access)• Project scope (substations)

• SECTION 1 Material Damages: External factors• Grid structure• Location (Natural exposure)• Project scope (substations)


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Pure Insurance Aspects

According to countries, grids are different.According to operation systems the alternatives are different DURING STARTING OF TESTSDespite damage on connectors (section 1 and clients factories TPL), consequences are different, risks are or are not enhanced.

FOCUS ON EXTERNAL FACTOR:GRID FACTOR, action on TPL and DSU

The operator splits the substation into 2 separated elements and saves the grid from the domino effect

http://fr.wikipedia.org/wiki/Fichier:Grid-spiderweb.svg

http://fr.wikipedia.org/wiki/Fichier:Grid-artere.svg

http://fr.wikipedia.org/wiki/Fichier:Grid-tree.svg

http://fr.wikipedia.org/wiki/Fichier:Report_de_charge_etat1.svg


http://fr.wikipedia.org/wiki/Fichier:Report_de_charge_etat2bis.svg



14IMIA Info

MPL Considerations

Hazards MPL ScenariosFrequency Severity

H M L H M L

Natural hazards

Earthquake Total loss of most of the towers (incl. foundations) and cables for projects within50km from the epicentre.

1)

X

Ice and snow accumulation Large sections of the line (e.g. highest elevation amsl) can be affected by thesame event resulting in towers and cable collapse. X

Wind storms Large sections of the line can be affected (mainly towers) for a continuous periodalso during cable laying. 2) X

Flood Total loss of foundations and earthworks for large sections (e.g. in a valley) pluspossible towers collapse. X 3)

Landslides and avalanches Limited sections affected by total losses resulting in consistently increased costsof /time for reconstruction. X

Lightning Lightning storms usually affect limited areas with possible damages to a limitednumber of substation(s) and/or single towers. X

Subsidence Local effects depending on subsoil conditions affecting towers’ foundations (also as consequence of EQ). X

External Hazards

Aircraft impact Minor local damages depending on nearby airfields and missing signals duringcables laying across valleys. X X

Bush fires From limited to large sections affected by bush fires ignited by external causesresulting in damages to towers (jeopardized stability) and cables (efficiency). X X


15IMIA Info

MPL Considerations

Terrorism & SRCC Local attacks (e.g. explosive devices) to destroy substations or single towersare most likely limited to restricted areas/sections. X X

Theft Theft of minor to moderate quantities of valuable goods (bulky items) stored atthe construction site or partially assembled along the line. X X

Nearby man-made hazardsRailway lines, motorways, other overhead lines, power plants, dams(basins/tailing facilities) etc. which bring additional exposure due to relatedactivities (e.g. fuel , pressure vessels explosions or flood waves).

X 4) X

Project intrinsic hazards

Fire The most exposed items are substations and storage areas and PML usuallyrefers to the largest fire unit. X X

Faulty design and workmanship

Serial items (e.g. towers, cables or insulators) can suffer losses triggered bythe same fault (faulty workmanship) although well-consolidated technologiesand material allow considering the exposure as moderate.

X 5) X

Construction operationsLifting, erection and cable laying operations are intrinsically risky given specialequipments and high rise structures although related to limited sections (e.g. 1tower total loss because of crane’s jib failure).

X X

Hazards MPL ScenariosFrequency Severity

H M L H M L


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RESULTING RISK MATRIX


17IMIA Info

RecommendationsTo be in position to handle the risk in a good shape, some subjects shall be carefully weighed:

1. Phasing and routing documents are mandatory2. Work in section clause (according to standards)3. Open foundation clause4. Pilling clause5. Serial loss clause6. The flood exposure can be limited by adding an endorsement

which provides limitation to the return period. 7. Fire fighting facilities8. Crops and forest for TPL9. Wind speed, and more generally whether limits especially with

helicopters and - DSU cover.10. Damages to access to the site11. Temporary camps and stores12. Partial hand-over 13. Grid condition (DSU)


18IMIA Info

ConclusionThe risk is not easy to handle as a lot of factors are playing on the projects.

Taking into account the costs and speed of works, over head T & D lines are not “as been” systems and will remain day to day risks for underwriters. (see major projects on renewable energy to produce and carry power from a continent to another one.

Major recommendation is to require information to reduce incertaity and apply good sense of business.

Thank you for your attention!

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