Specifications

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2. WINDING WIRE
2.1 INTRODUCTION
Winding wire is solid wire, which, to allow closer winding when making electromagnetic
coils, is insulated only with varnish, rather than the thicker plastic or other insulation commonly
used on electrical wire. It is used for the winding of electric motors, transformers, inductors,
generators, speaker coils, etc.
A wire is a single, usually cylindrical or rectangular cross-section, length of metal. Wires
are used to carry electricity and telecommunications signals. Wire is generally formed by drawing
the metal through a hole in a die or draw plate. Standard sizes are determined by various wire
gauges. The term wire is also used more loosely to refer to a bundle of such strands, as in
‘multistranded wire’, which is more correctly termed a wire rope in mechanics, or a cable in
electricity.
The metals must in the first place be ductile and strong in tension, the quality on which the
utility of wire principally depends. The metals suitable for wire, possessing almost equal ductility,
are platinum, silver, iron, copper, aluminium and gold; and it is only from these and certain of
their alloys with other metals, principally brass and bronze, that wire is prepared. By careful
treatment extremely thin wire can be produced. Copper wires could be plated with other metals,
such as tin, nickel, and silver to handle different temperatures, provide lubrication, provide easier
stripping of rubber from copper. Wire used to carry electricity is made up of materials having
very low resistivity such as pure copper or aluminium.
2.2 PROPERTIES OF CONDUCTORS
Electrical Properties: 1) The conductivity must be good. 2) Electrical energy dissipated in
the form of heat must be low. 3) Resistivity must be low 4)Temperature resistance ratio must
be low.
Mechanical Properties: 1) Good Ductivity: It is that property of a material which allows it to be
drawn into a wire. 2) Solderability: The joint should have minimum contact resistance.
3) Resistance to corrosion: Should not get rusted when used outdoors. 4) Withstand stress
and strain. 5) Easy to fabricate.
Economical Factors: 1) Low cost 2) Easily available 3) Easy to manufacture
Characteristics of a Good Conductor Material: The conductor materials should have low
resistivity so that any amount of power can be transmitted without much loss in the conductor.
2.3 THE CHOICE OF A CONDUCTOR MATERIAL DEPENDS ON THE FOLLOWING
FACTORS: 1) Resistivity of the materials 2) Temperature coefficient of resistance 3)
Resistance against corrosion 4) Oxidation characteristics 5) Ease of soldering and welding
6) Ductility 7) Mechanical strength 8) Flexibility and abundance 9) Durability and low cost 10)
Resistance to chemicals and weather
Commonly Used Conductor Materials: Copper and Aluminium
Copper: 1) Pure copper is one of the best conductors of electricity and its conductivity is highly