GIL Concept

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CONTENTS

GAS INSULATED LINE (GIL) BASIC LAYOUT OF GIL

MAIN COMPONENTS

GENERATIONS OF GIL

INSTALLATION OF GIL

TECHNICAL DATA

COMPARISON OF LOSSES

ADVANTAGES DISADVANTAGES

APPLICATIONS

SUMMARY

REFERENCES



GAS INSULATED LINE

Gas Insulated Line invented in 1965 by Massachusetts

Institute of Technology

GIL consists Aluminium conductor surrounded by mixture of N2 and SF6 inside the enclosure.

GIL system first installation in Black Forest as long ago as

1975 of about 4km. length.

GIL system can be used both in above & below ground



BASIC LAYOUT OF GIL



MAIN COMPONENTS

Conductors & enclosures

Insulators & particle traps

Plug in contacts

Aluminum bellows

Enclosure joints



GENERTIONS OF GIL

1st Generation 2nd Generation

pure SF6

Aluminium pipes with

straight beads

9m long transport

units

Hand welding

Application of disc

spacers

N2-SF6 gas mixture

Spiral welded aluminium pipes

Transportation units between

11.5m and 13.5m

Automated Orbital welding

Bending of the whole tube

possible to radii > 400 m

Application of support

insulators



INSTALLATION OF GIL

1. Aboveground Installation

GIL are unaffected by

high ambient

temperatures, intensive

solar radiation or severe

atmospheric pollution.

High transmission power

can be achieved withaboveground installation.

Corrosion protection is

not required.



2. Tunnel Installation

With this method of installation

the land above the tunnel can befully restored to agricultural use.

The system stays accessible for

easy inspection and high

transmission capacity is ensured.

3. Vertical Installation

Top solution especially for

cavern hydropower plants.

GIL systems pose no fire

risk, they can be installed in a

tunnel



4. Direct burial Installation

These systems are coated with a

continuous polyethylene to

safeguard corrosion resistant

Aluminium alloy.

The land can be returned to

agricultural use with very minorrestrictions.



TECHNICAL DATA OF GILSpecifications Rating

Rated Voltage 400-500 kV

Impulse withstand voltage 1425-1675kV

Rated Current 2000-4500kA

Rated short-circuit current 63kA/3s

Rated Transmission Load 2200-3900 MVA

Capacitance 55 nF/km

Overload Capability 100 % depends on design &

requirements

Insulating Gas mixture 80 % N2 & 20 % SF6

Typical system length 100 m to 100 km

Electromagnetic Field strength 1 µT

Outer Diameter 375 to 500 mm

Weight per phase 50 kg/m



COMPARISON OF LOSSES



ADVANTAGES

High transmission capacity

Low transmission losses

Low capacitance

High reliability

High operational safety (no fire risk, no external impact incase of internal failures).

No practical ageing of components

Very low external magnetic field

No interference with the communication systems



DISADVANTAGES

Length of each GIL section is limited.

Particle contamination lower the insulating reliability of

GIL. Breakdown of insulator.

Earthquake resistant design must be considered.

SF6 gas is harmful to ozone.



Installation in tunnels

Ideal for environments that

are sensitive to electro-magnetic fields.

Suitable for metropolitan

areas where high energyrate is required.

Well suited for high power

transmission.

APPLICATIONS



SUMMARY

Sealed for lifetime

Continous welded

High capacity Low losses

Long lifetime through particle trap

No reactive compensation (1000km)

No ageing of insulation

Automatic reclosure functionality

Low external electromagnetic fields

No fire hazard



REFERENCES[1]. Koch H.,Kumar A., Christl N., Lei X., Povh D., Retzmann D., Advanced

Technologies for Power Transmission and Distribution – Benefits and Impact of

Innovations, Siemens Brochure, 2010.

[2]. Hillers T., Koch H., Gas-Insulated Transmission Lines (GIL): The solution

for high power transmission underground, IEEE, PES Power Delivery

Conference, Madrid, Spain, 08/1999.

[3]. Giebel G., Nielson H., Hurley B., Bigger transmission distance with lower

load factors: the European dilemma, Modern Power System, 10/2005.

[4]. IEC 62271-203 High-voltage switchgear and control gear – Part 203: Gas-

insulated metal-enclosed switchgear for rated voltages above 52 kV, IEC andGeneva, Switzerland, 2003-11.

[5]. Benato R., Fellin L, Marzenta D., Paolucci A., Gas-Insulated Transmission

Lines: excellent performance and low environmental impact, Vol.1 pp. 385 – 405,

Napoli, Italia, 12. – 18. May 2000.



THANKYOU

GIL Concept

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