Overhead Line Conductor Materials 2021

Conductors are a very important component in the transmission and distribution of electricity. A large portion of the capital is spent on the purchase of these conductors. So it is very important to choose the right component, size, and volume of the conductor when choosing a conductor.

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Conductors used for power transmission and distribution must have the following characteristics:

Must have high electrical conductivity.
Must be done to withstand high tension so that it can withstand mechanical stress.
The price should be cheap so that it can be used far and wide.
Should be of less relative importance so that the weight of the conductor is less per unit volume.

However, not all of the above features can be found in a conductor. Therefore, in the case of conductor selection, the conductor must be selected by maintaining the necessary balance between the material, cost, and electrical and mechanical properties of the conductor.

Metals used to make conductors:

The following metals are commonly used to make overhead line conductors:

Copper conductor
Aluminum conductor
Steel cored aluminum conductor
Galvanized steel (galvanized steel) conductor
Cadmium copper conductors etc.

Now we will try to know the details about these materials-

Copper conductor:

Copper is considered to be the ideal material for conductors of overhead lines due to its high electrical conductivity and tensile strength. Hard drawn standard copper conductors are commonly used as conductors in overhead lines.

Below are some of the qualities of copper conductors:

Copper conductors have a much higher electrical conductivity than other conductors.
These conductors tend to be much more tensile strength.
Due to the high current density of copper, conductors with low cross-section are required for conductors.
The lower the cross-section or thinner the conductor, the lower the air pressure in the line.
Its relative importance is high.
This metal is much more homogeneous.
Corona wastage due to high voltage in copper conductors is less.
It does not decay easily due to a short circuit due to a high melting point.
Copper has a long life.
Copper can be sold at a higher price even if abandoned.

Copper is certainly the ideal conductor for transmission and distribution, no doubt. But due to its high cost and inadequacy, it is rarely used. Aluminum conductors have become quite popular instead of copper conductors at present.

Aluminum conductor:

Aluminum is cheaper than copper and lighter in weight. But its conductivity and tensile strength are much less. Although copper is second only to copper as a conductor, aluminum conductors are the most commonly used for transmission due to the high cost of copper conductors.

Below are the comparative features of copper conductors and aluminum conductors-

Aluminum has low electrical conductivity and 60 percent conductivity compared to copper.
Its cross-section is larger than that of copper conductors, so it swings more in the air and has more sag. In addition, aluminum conductors are about 1.26 times larger in diameter than copper conductors with the same resistance. As a result, the supporting towers have to be built much higher.
The relative importance of aluminum (2.61 g / cc) is less than the relative importance of copper (8.9 g / cc). So in terms of mass, the same amount of aluminum conductors is about one and a half times less than copper conductors. This is why supporting towers for aluminum conductors are not as strong as supporting towers for copper conductors.
Aluminum conductors are lighter in weight and take more swings, so large cross-arms have to be used for this.
Corona dissipation at high voltages in aluminum conductors is lower than in copper. However, due to the short circuit caused by the melting point of aluminum, it is easily corroded.

Considering the conductivity, tensile strength, cost, weight, etc. of metal, aluminum is being used more than copper. However, due to the excess of sag (sag) of aluminum conductors, steel cores are now used as aluminum conductors in conjunction with steel.

Steel cored aluminum conductor:

Aluminum conductors are less stress-tolerant, so they have extra sag in the case of transmission, which means that poles or towers have to be placed a short distance away. Which is expensive and unsuitable for remote transmission.

To solve this problem, its tensile strength is increased with the help of steel conductors with aluminum conductors, which is known as steel core aluminum.

Which is abbreviated as A.C.S.R. (aluminum conductor steel reinforced)? This conductor surrounds the steel and wraps the aluminum around it in a 1: 8 ratio, making it quite tensile. However, if the tensile strength of the conductors needs to be further increased, their cross-section ratio is made 1: 4.

Below are some features of this conductor-

Its electrical conductivity is less than that of copper.
Its tension tolerance is high.
The use of aluminum and steel results in less weight and higher tensile strength, resulting in less wire sag.
As the wire sag decreases, its span length increases and the height of the tower decreases.
Its relative importance is less than that of copper.
Its price is also relatively low. And
It has a longer lifetime.

Galvanized steel conductor:

Steel has high tensile strength and can withstand storms, rains, and bad weather. It is usually used for short length transmission lines in galvanized rural areas due to its low cost. But this conductor cannot be used on long transmission lines.

This conductor is unsuitable for use in long transmission lines due to the following reasons-

Its conductivity is much lower than that of copper.
The internal reaction is much higher.
High resistance did.
This causes loss of AD current and hysteresis.
These conductors are prone to rust and rapid erosion (if not rusted).

Galvanized steel conductors are mainly used for stay-wire, earth wire, etc. in rural areas.

Cadmium copper conductor:

In some cases, copper is mixed with cadmium in the material of the conductor. Adding 1% or 2% cadmium to copper increases its tensile strength by about 50% and then its conductivity is only 15% less than that of pure copper.

Cadmium copper conductors are mainly used for very long spans. However, due to the high cost of cadmium, such conductors are used only in areas where there is potential for economic gain. It goes without saying that it is not used in all other areas.

Overhead Line Conductor Materials 2021