why aluminium is used in Transmission Lines | material used in Transmission Lines

Transmission lines: 

 Definition transmission Line helps in the transfer of electricity from a power plant or power station to the various substations.

 Transmission line is an important part of power system. The cost and life of transmission line majorly depend on the material of conductor for transmission line.The most extensively used material is aluminium. ACSR conductor is most popular material used for high voltage overhead transmission lines. 

Required Properties of Conductor which is used in Transmission Line

>High conductivity

>High tensile strength

>Light weight

>High resistance to corrosion in whether conditions

>High thermal stability

>Low coefficient of thermal expansion

>Low cost

Conductivity :

As we all know that we select any conductor by looking at conductivity of conductor .Meaning we always use the wire inside which the resistance is minimum so that current can flow easily.

 So if we talk about the best conductive material of electricity, then silver comes first in the number. (Silver is a material in which the current passes easily).

                             Silver

Thee conductivity of silver is said to be the best.

            Metal                    Resistivity 

                                          (10^- 6 ohm-cm )

         1.silver                      1.55

         2.copper                  1.7

         3.gold                      2.2     

         4.aluminium            2.7 

 After this, the name of copper comes on the second number, after copper, gold comes on the third number.

 And if we talk about aluminum, then it comes at number 4 in this list.

 now you know which material is the best conductor. But here we have a problem that the silver and gold are very worthy. So it is completely impossible to use the wire of both these materials.

                                    Gold

 Because a kilogram of silver costs around 40,000 rupees and if we talk about gold, then it is about 40,00,000 kg. Which is much more expensive.

 So now we have only two materials left:

 <1>Copper 

                                  Copper

<2> Aluminum 

 

                                 Aluminum 

Cost:

The cost of both these materials is very low. You get 1 kg of copper for 500 rupees, while the same aluminum gets 1 kilogram for just 100 rupees (generally).

 Cost wise (because of the price) -1 Kg of copper costs around 500 rupees, while aluminum we get only 100 rupees a kilogram. So even if we double the thickness of this aluminum wire, the price of 2 kg of aluminum will be only Rs 200, which is about 60% less than copper.

Difference between Copper and Aluminum: 

 Resistivity- 

Copper is a better material than aluminum in terms of resistance. Copper resistance is 60% less than aluminum.

 For example, if we have copper and aluminum conductors of exactly the same size, if the resistance of copper wire is 1 ohm, then the resistance of aluminum wire of this size will be 1.6 ohm. So we came to know that the resistance of copper is low.

 :There is a rule of resistance that if we enlarge the size of the material, we will make it thicker. The resistance then decreases. (R = pl /A )

 :If we do this with aluminum, if we double the aluminum wire, the resistance of the wire will be reduced from 1.6 to 0.8.

 Weight - 

The second major difference after this is on the weight of these two. And this point is very important for wire selection of transmission line. Because we all know if our wire will have more weight. So at that time we also have to install towers of high power so that it can withstand the wire of high weight.

:This means that the difference in the weight of the wire directly comes at the cost of the tower.

:The weight of copper is more than aluminum.

:For example, if a copper wire weighs 1 kg, the aluminum wire of exactly the same size will weigh only 0.33 KG.

: So if we use aluminum, the cost of building transmission line towers will come down, because aluminum wire is lighter in weight than copper.

 Long life - 

we do not use insulation on the transmission line wire. So if we use copper wire outdoors without insulation, then at this time we have to give a lot of maintenance to the copper wire.

                               Rust - corrosion

Corrosion takes place very quickly over copper. And if we use the same aluminum, then there is no problem of rusting in it. So if we use aluminum instead of copper, it will be maintenance free and the life of this wire will be more than copper wire.

Because of above advantages over copper aluminium is used in Transmission Lines.