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TRANSMISSION LINE

CONDUCTORS

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Transmission line

A transmission line, or feed line, is what

lets you put the antenna andtransmitter/receiver in different places for

Elevation

Convenience Safety

Space

Location

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Transmission line conductors

The conductor used in transmission

line is to carry electric current. It is desired to have low resistance so

that power loss is minimum.

It must have a good mechanicalstrength to bear the tension of line

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Materials used as conductors of a

transmission line

COPPERALUMINIUM

ACSR (Aluminum conductor withsteel reinforcement)

GALVANISED STEEL

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COPPER

Copper has good conductivity. Good

conductivity makes it the mostsuitable material to be used as

conductor of transmission line.

Copper has high tensile strength.

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COPPER

Hard drawn bare copper conductors

is used in transmission line.It has good mechanical strength.

Copper has high CostIts poor availability restricts its use.

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ALUMINIUM

Conductivity of aluminium is poor

than copperMechanical strength of aluminium is

poor than that of copper

Poor mechanical strength does not

permit its use as conductor material

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ALUMINIUM

In transmission lines.

Weight of aluminium is less thancopper

Cost of aluminium is less.Its use as ACSR conductor is very

common.

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ACSR

Due to less availability of aluminium

And also for reducing cost, ACSR(aluminium conductor with steel

reinforcement) has become very

popular.

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ACSR

It has a core of galvanised steel

surrounded by aluminium strands toprevent corrosion.

Steel takes the mechanical stress,

while aluminium strands carry the

current.

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ACSR

Due to high mechanical strength, sag

is small.Therefore, larger spans can be used.

However skin effect is verypronounced in these conductors.

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ACSR

A.C. current flows through external

periphery of conductor and hencemakes use of good conductivity of

aluminium.

Steel helps in increasing the

mechanical strength.

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Galvanised steel

Due to high tensile strength,

galavanised steel can be used atextremely large spans.

Galvanisation protects steel against

corrosion.

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GALAVANISED STEEL

They are more in use in rural areas

where cost is the main consideration.Also, their use is limited to the

transmission of small power over

small distances.

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GALVANISED STEEL

They are also used as earth wire on

poles, as stay wires and have othersimilar applications.

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Comparison between properties of

copper and aluminium

S.no. Properties Copper Aluminium

1. Electricity

conductivity

0.975 0.585

2. Resistivity 1.777 2.826

3. Specific gravity 8.89 2.70

4. Tensile strength 380x 10^6 180x 10^6

5. Coefficient of linearexpansion perdegree celcius

16x10^-6 24x10^-6

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COMPARISON BETWEEN THE PROPERTIES

OF COPPER AND ALUMINIUM

S.no. Properties Copper Aluminium

6. Temperature coefficient

of resistance

0.003 per

degree celcius

0.004 per

degree celcius

7. Ratio of conductivenessfor equal area

1 0.6

8. Ratio of diameters forequal resistance

1 1.29

9. Ratio of weights for

equal resistances

2 1

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THANK YOU.

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