conductor (redirected from Conduction (disambiguation))

conductor

Any of various substances that allow the flow of electric current or thermal energy. A conductor is a poor insulator because it has a low resistance to such flow. Electrical conductors are used to conduct electric current, as in the metal wires of an electric circuit. Electrical conductors are usually metallic. Thermal conductors allow thermal energy to flow because they do not absorb radiant heat; they include materials such as metal and glass.

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conductor

A material that can carry electrical current. Contrast with insulator.

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conductor

1. a person who conducts an orchestra, choir, etc.

2. US and Canadian a railway official in charge of a train

3. a substance, body, or system that conducts electricity, heat, etc.

4. See lightning conductor

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Conductor (electricity)

Metal wires, cables, rods, tubes, and bus-bars used for the purpose of carrying electric current. (The most common forms are wires, cables, and busbars.) Although any metal assembly or structure can conduct electricity, the term conductor usually refers to the component parts of the current-carrying circuit or system.

Wires employed as electrical conductors are slender rods or filaments of metal, usually soft and flexible. They may be bare or covered by some form of flexible insulating material. They are usually circular in cross section; for special purposes they may be drawn in square, rectangular, ribbon, or other shapes. Conductors may be solid or stranded, that is, built up by a helical lay or assembly of smaller solid conductors.

Insulated stranded conductors in the larger sizes are called cables. Small, flexible, insulated cables are called cords. Assemblies of two or more insulated wires or cables within a common jacket or sheath are called multiconductor cables.

Bus-bars are rigid, solid conductors and are made in various shapes, including rectangular, rods, tubes, and hollow squares. Bus-bars may be applied as single conductors, one bus-bar per phase, or as multiple conductors, two or more bus-bars per phase. The individual conductors of a multiple-conductor installation are identical.

Most wires, cables, and bus-bars are made from either copper or aluminum. Copper, of all the metals except silver, offers the least resistance to the flow of electric current. Both copper and aluminum may be bent and formed readily and have good flexibility in small sizes and in stranded constructions. Aluminum, because of its higher resistance, has less current-carrying capacity than copper for a given cross-sectional area. However, its low cost and light weight (only 30% that of the same volume of copper) permit wide use of aluminum for bus-bars, transmission lines, and large insulated-cable installations.

For overhead transmission lines where superior strength is required, special conductor constructions are used. Typical of these are aluminum conductors, steel reinforced, a composite construction of electrical-grade aluminum strands surrounding a stranded steel core. Other constructions include stranded, high-strength aluminum alloy and a composite construction of aluminum strands around a stranded high-strength aluminum alloy core.

For extra-high-voltage transmission lines, conductor size is often established by corona performance rather than current-carrying capacity. Thus special “expanded” constructions are used to provide a large circumference without excessive weight. Typical constructions use helical lays of widely spaced aluminum strands around a stranded steel core. The space between the expanding strands is filled with paper twine, and outer layers of conventional aluminum strands are applied.