CONDUCTORS

Conductors are materials with electrons are loosely bound to their atoms or materials that permit free motion of a large number of electrons. Atoms with only one valance electron such as copper, silver, gold are examples of good conductors. Most of the metals are good conductors

Properties of electrical conductors

            In equilibrium condition the conductors exhibit the following properties

a)      Resistance

Conductors are those substances which offer such a small resistance

b)      Inductance

When a conductor is used as ac supply a magnetic flux is produced, which consist of two parts. One is internal flux and other is external flux. The internal flux is very low as compare to external flux. Due to this flux linkage to the conductor itself an inductance is come into picture. This inductance results in extra voltage drop in conductors. More over this inductance is also effects to skin effect and proximity effect 

c)      Electric field

There is no electric field inside a good conductor.

d)      Charge density

The electric charge does not exist inside the conductor. The charge exits only on the surface of a conductor.

e)      Potential
                             All points of a conductor are at the same potential

Selection of a conductor

The selection of a conductor depends as follow

·         Electrical conductivity

·         Strength

·         Cost

·         Availability

·         Corrosion

·         Ductile and malleable 

                        COMMONLY USED CONDUCTORS

silver wire 
                  Silver is an excellent conductor of electricity no other metal can compare with it. The main problem of silver wire is it cost (A silver wire would cost over 100 times of a copper wire) because Silver is a jewelry metal

Copper

            Copper is commonly used for making electrical wires. The copper wiring is known as heaven of electrician due to its property

1)      Copper is an excellent conductor of electricity

2)      Copper can be stretched to a good length without breaking

3)      Copper wire can withstand adverse climatic conditions

4)      Copper wire can withstand sustain temperature fluctuations

Gold

            Gold is an efficient conductor that can be used in very low current applications also. The gold is free from corrosion but it’s costly (gold is a jewelry metal). The gold is used for electronic components such as connectors, switch and relay contacts, connecting wires etc.

Aluminium

            Aluminium wiring is a type of electrical wiring for residential construction or houses that uses aluminium electrical conductors. Aluminium provides a better conductivity and it is also used for power grids, includes overhead power transmission lines and local power distribution lines as well as for power wiring of some applications. It is better than the copper as compare with the basis of cost and weight. The main drawback of the aluminium is corrosion

Aluminium conductor steel reinforced cables 

         It is a type of high capacity cables with high strength and the standard conductor used for overhead power lines. The outer strands of the ACSR cable is purely aluminium and the center strands of ACSR cable is steel.

            The outer strand aluminium provides excellent conductivity, low weight and low cost. The steel provides higher strength so the mechanical tension of the conductor is improved

Lead

Lead is a metal so it conducts electricity, but practically lead wires are not used in wiring because lead is soft, malleable and melts at relatively low temperature. Lead is used as conductor as in Printed Circuit Boards

Iron

            Iron is a good conductor, it have free electrons. Practically iron is not used for wiring because it shows different conductivity levels at different temperature.

Brass

            Brass is non-ferrous metal with excellent electrical and thermal conductivity as well as good corrosion resistance, ductility and strength. Brass is commonly used for making switch terminals

Carbon

            Graphite is an allotropes of carbon, which is very good conductor. Carbon is used as conductor in generator and motor.

Tungsten

            Tungsten is a hard and rare metal. It has the ability to withstand high temperature. The tungsten is used as filament of bulb

Nichrome

            Nichrome is an alloy of Nickel, Chromium and Iron. The nichrome wire is commonly used as resistance wire.