Stranded Conductors

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Stranded conductors and

Bundled conductors


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Stranded conductor

What is Stranded conductor?

Instead of a single rounded conductorstranded conductors made from conductors of

smaller radii are used. Group of small radii

conductors is known as the Stranded

Conductor.


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Stranded Conductor


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Advantages of stranded conductor

over single rounded conductor

The stranded conductor has larger surface area

so the electric field strength near the conductor

surface is reduced. As a result the stranded

conductor is less likely to experience corona.

Simultaneously it has irregular surface so the

corona effect will be more pronounced.

It depends upon the factor which is moreaffecting that has to be taken into consideration.


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The stranded conductor is more flexible than a

single rounded conductor of equal capacity.

For higher capacity conductor the conductor

diameter may become large enough that use

of one single conductor of large diameter

becomes non-flexible.

Stranded conductors have more mechanical

strength.


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Types of stranded conductors

Three types of conductors are mainly used for

transmission purposes:

All Aluminum Alloy Conductor (AAAC)

Aluminum Conductor Steel Reinforced (ACSR)

Aluminum Conductor Alloy Reinforced (ACAR)


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Bundled Conductor

What is bundled conductor?

In high capacity transmission lines instead ofone conductor (ACSR/AAAC conductor) per

phase, two, three or four conductors are used.

This is called bundled conductor.


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http://1.bp.blogspot.com/_U3umjVzCXTA/TRg08Kb-ZhI/AAAAAAAAAUk/O_EmGTxx9lE/s1600/ACSR+bundled+conductor.jpg


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http://2.bp.blogspot.com/-LcUjpub5eR8/Tse2clY9oII/AAAAAAAAADA/aIWouqjqNLY/s1600/bundled.jpg


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Advantages of Bundled Conductors

Bundled conductors per phase reduces the

voltage gradient in the vicinity of the line. Thus

reduces the possibility of the corona discharge.

Improvement in the transmission efficiency asloss due to corona effect is countered.

Bundled conductor lines will have higher

capacitance to neutral in comparison with singlelines. Thus they will have higher charging currents

which helps in improving the power factor.


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Bundled conductor lines will have highercapacitance and lower inductance than ordinarylines they will have higher Surge ImpedanceLoading (Z=(L/C)1/2). Higher Surge ImpedanceLoading (SIL) will have higher maximum powertransfer ability.

With increase in self GMD or GMR inductance perphase will be reduced compared to singleconductor line. This results in lesser reactanceper phase compared to ordinary single line.

Hence lesser loss due to reactance drop.


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Vibrations and dampers

Aeoline vibrations Galooping or Dancing


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Vibration dampers

To reduce the vibrations dampers are used.

Widely used dampers are Stock bridge

dampers

A Stockbridge damper is a tuned mass

damper used to suppress wind-induced

vibrations .
http://en.wikipedia.org/wiki/Tuned_mass_damperhttp://en.wikipedia.org/wiki/Tuned_mass_damperhttp://en.wikipedia.org/wiki/Tuned_mass_damperhttp://en.wikipedia.org/wiki/Tuned_mass_damper


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http://en.wikipedia.org/wiki/File:Stockbridge_damper_(cropped).jpg


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The dumbbell-shaped device consists of two

masses at the ends of a short length of cable

or flexible rod, which is clamped at its middle

to the main cable. The damper is designed todissipate the energy of oscillations in the main

cable to an acceptable level.
http://en.wikipedia.org/wiki/Dumbbellhttp://en.wikipedia.org/wiki/Dumbbell


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http://en.wikipedia.org/wiki/File:Stockbridge_damper_POV.jpg

Stranded Conductors

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