1. 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
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 jewellery metal.
2. 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 jewellery 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
3. copper as compare with the basis of cost and weight. The main drawback of the aluminium
is corrosion
Aluminium conductor steel reinforced cable
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.
4. 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
5. Carbon
Graphite is an allotrope 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.