Conductor Materials- Electrical Conductor Materials

Contents

Conductor Materials for conducting electric current

The conductor materials used for transmission and distribution of electrical energy must have the following characteristics.

Characteristics of good conductor materials are;

It should have a low cost.
It should be light in weight
It should have high conductívity.
It should not be brittle
It should have a high tensile strength to withstand mechanical stresses.
Low specific gravity in order to give low weight for unit volume.
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Aluminum, Copper, and galvanized steel conductors are generally used for the transmission and distribution of electrical energy.

The conductor materials are,

(1) Copper

The resistivity of annealed high conductivity copper is 0.01724 W-m/mm2 at 20°C.

The electrical resistance of copper varies with temperature.

High conductivity copper is available in the form of fully annealed or the hard drawn state depending on the properties required for the items under manufacture.

Hard drawn copper is having double, the tensile strength of annealed copper.
Insulated cables consist of annealed copper whereas overhead lines consist of hard drawn copper.

The busbars for heavy current conductors of relatively short
length is made o1 hard drawn copper.

(2). Aluminium.

Aluminum is replacing copper in many of its applications.

It has a conductivity of 62% that of copper.

In high voltage transmission line aluminum is used as supports, conductors and conductor accessories.

Aluminum is also used as the conductor for distribution cable.

(3) Aluminium Conductor Steel Reinforced (A.C.S.R).

ACSR conuctor — ACSR- Aluminium Conductor Steel Reinforced

These conductors are used for long-distance high voltage overhead transmission lines.

A.C.S.R. consists of a core of galvanized steel strand surrounded by a number of aluminum strands.

The core is galvanized steel to prevent rusting and electrolytic corrosion. The steel core takes a greater percentage of mechanical stresses and the aluminium carries the current. A.C.S.R. conductors have high tensile strength.

(4) Cadmium copper alloys.

Cadmium copper alloy contain 0.6 to 1% cadmium when cadmium copper is hard drawn.

Its tensile strength is 50% greater than that of hard drawn copper.

It is used for overhead lines and for contact wires for overhead lines.

Advantages of Stranding the Conductors

Stranding of conductors

(1) They are more flexible and durable, therefore, can be handled conveniently.

(2) The surface area of stranded conductor is more as compared to the surface area of an equivalent single solid conductor.

As the heat radiating capacity is proportional to the surface area, therefore, a stranded conductor has more heat radiating capacity as compared to a single solid conductor.

Conductor Materials- Electrical conductor materials