Glossary of Terms

Glossary of Terms

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Alternating Current

Electrical current that continually reverses its direction, giving a definite plus and minus waveform at fixed intervals. Its unit of measure is Hertz (Hz).

Aluminum

Aluminum is a silvery and is ductile, malleable and resistant to corrosion, but prone to acids and alkalis. It is primarily used in transportation, packaging building, electrical and consumer durable products, as well as a conductor of electricity in electrical cables.

Ambient Temperature

Temperature of the medium, to which an object is exposed.

Annealing

Heating to and holding at a suitable temperature and then cooling at a suitable rate, for such purposes as reducing hardness, improving machinability, facilitating cold working, producing a desired microstructure or obtaining desired mechanical, physical or other properties. When applied to ferrous alloys, it implies a heat treatment designed to soften a cold worked structure

Anti-Oxidant

Substance, which prevents or slows down the decomposition or degradation of materials exposed to oxygen or peroxides.

Armor

Mechanical protection of a cable consisting of metallic tape, layer or braid, made of aluminum or steel.

Armored cable

A multi-conductor cable in which the metal armor may be used as the ground return path. Can be designated as Type AC (Armored Cable), Type ACT (Armored Cable with Thermoplastic conductors), and Type ACTH (Armored Cable with Thermoplastic-insulated, heat-resistant conductors).

AWG

Acronym for American Wire Gauge, formerly known as Brown & Sharpe Gauge. In this system, 1 mil is equal to 0.001 inch. Lower AWG number indicates larger diameter.

Binder

 

A spirally wrapped tape or thread used for holding cable components in place until additional manufacturing operations are performed.

Braid

A fibrous or metallic group of filaments interwoven in cylindrical form to form covering over one or more wires. Formed by laying a number of strands of material diagonally in such a way that one or more strands pass alternately over and under one or more strands laid up in the opposite direction.

Breakdown Voltage

The voltage at which the insulation between two conductors breaks down, allowing current to flow between conductors.

Building Wire

Insulated wires, up to a maximum of 600V, that are used in buildings for light power.

Cable Filler

Material use to fill the spaces between the intersection of multiple-conductor cables spaces allowing the formulation of a cable core that is circular in shape.

Capacitance

The property of a system of conductors, electronic components and dielectrics that permits the storage of electricity when potential differences exist between the conductors. It is measured in farads. For cables it is usually measured as Pico farads per foot (pf/ft), which indicates how much charge the cable can store within itself. If a voltage signal is being transmitted by a twisted pair, the insulation of the individual wires becomes charged by the voltage within the circuit. Since it takes a certain amount of time for the cable to reach its charged level, this slows down and interferes with the signal being transmitted. Digital data pulses are a string voltage variations that are represented by square waves. A cable with a high capacitance slows down these signals so that they come out of the cable looking more like “saw-teeth” rather that square waves. The lower the capacitance of the cable, there better it performs at higher frequencies.

Circular Mil (cmil) or (CM)

Unit used to express the area of a wire. A circular mil is the area of a circle one 1/1000 of an inch (3.9 x 10-5mm.) in diameter. As the number of circular mils increases, the size of a wire increases.

Compact conductor

Stranded conductor drawn to deform the round wires to fill the normal interstices between the wires in a strand.

Concentric-lay cable

A concentric lay conductor or multiple conductor cable composed of a central core surrounded by one or more layers of helically laid conductors. Each of these succeeding layers is applied with an opposite direction of twist.

Concentric Stranding

A group of uninsulated wires twisted so as to contain a center core with one or more distinct layers of spirally wrapped, un-insulated wires laid overall to form a single conductor.

Concentricity

Measure of location of center of conductor, in a wire or cable with respect to the geometric center of the circular insulation.

Conductivity, Electrical

A term used in describing the capability of a conductor to carry electric current. Usually expressed as a percent of IACS (International Annealed Copper Standard), which is defined as being 100 percent conductive.

Conductivity, Thermal

Ability of a material to conduct heat. The measure of the heat conducted, expressed in BTU per hour per sq ft of exposed surface, per oF difference between the adjacent hot and cold bodies, per in. thickness. Not to be confused with Heat Transfer.

Copper – Electrolytic

Highly pure copper that is refined by electrolysis and used for electrical conductors.

Copper, Oxygen-free

Copper containing neither copper oxide nor any residue of deoxidizers. Electrolytically refined copper that has been remelted and fabricated without the introduction of oxygen.

Creep

Change in dimension of a material under mechanical load over a period of time. The flow or plastic deformation of metals subjected to stress and for long periods of time.

Cross Linked Polyethylene (XLPE)

Common thermoset insulation for wire and cable, also known as XLPE. Polyethylene made from petroleum and natural gas undergoes a cross-linking chemical reaction that causes compound molecules to bond, forming heavier molecules with desired physical and chemical properties.

Cross-Linking

Phenomena found in thermosetting resins. Applied to polymer molecules, it is setting up of chemical links between the molecular chain.

Cross Sectional Area of a Conductor

Exposed area of a conductor, obtained by cutting perpendicular to its longitudinal plane. Units of measures are circular mils, square inches or square millimeters.

Current-Carrying Capacity (Ampacity)

The maximum current an insulated conductor can safely carry without exceeding its insulation and jackets temperature limitations.

Dielectric Constant (K)

A measure of the dielectric loss through an insulation and also indicates the charging current required for a conductor. It determines the electrostatic energy stored per unit volume for unit potential gradient. Also known as permittivity and specific inductive capacity.

Dielectric Strength

Maximum voltage an insulating material can withstand before breakdown. Also known as electric strength or disruptive gradient. It is expressed as voltage gradient (such as volts per mil).

Drain wire

Numerous small gauge bare wires applied concentrically about the insulation shield of a high voltage cable for the purpose of a fault current return path. Drain wires also provide a means of terminating laminated shields.

Drawing

The process of pulling wire at room temperature(cold) through a die that has a smaller opening, which reduces the cross-sectional area to a required size. Since the wire is deformed plastically in the die because of the pull exerted on it and the taper of the die, there is a limit to the reduction which can be made at one die, according to the amount of pull the wire can withstand without breaking.

Eccentricity

Measure of deviation in concentricity used in wire and tube manufacturing. In a hollowed product, it is the difference between the maximum wall thickness and minimum wall thickness at any one cross-section. Deviation is reported as plus or minus wall thickness fraction.

Elastomer

A rubber or rubber-like material that will stretch repeatedly to 200 percent or more and return rapidly and with force to its approximate original shape.

Elongation

The amount that a conductor can stretch before breaking when a pulling force is applied in tensile testing. The increase in the gauge length, measured after fracture of the specimen within the gauge length is usually expressed as a percentage of the original gauge length.

Embossing

Raised lettering, for identification, on the sheath material of cable produced by thermal induction.

Extrusion

The process of forming a product by continuously forcing a material through a die under pressure. In the wire industry, a plastic or elastomer and a conductor core are forced through a die to apply a continuous coating of insulation or jacket to the core or conductor.

Fault current

Current flowing as a result of short-circuit conditions.

Filler

1) A material used in multi-conductor cables to occupy large interstices formed by the assembled conductors. 2) A substance, often inert, added to a compound to improve properties and/or decrease cost.

Fire Resistant

Ability of cable material to avoid combustion for a specified period of time.

Fire Retardant

Property of a cable material that delay ignition for a given period of time and slows the spread of the flame once ignition has occurred.

Grounding Conductor

Conductor connecting non-current carrying metal parts of equipment or the grounded circuit to a grounding electrode.

Hard-drawn Wire

Hard drawn refers to the temper of wires that are cold drawn without annealing and work harden in the drawing process. Also refers to, wire that has been drawn to a specific size without being annealed.

Heat shock

Test conducted to determine the stability of material by exposing it to high temperature for short time interval.

Hygroscopic

Hygroscopic materials are those, which absorb and retain moisture from the air.

Insulation Resistance

Resistance offered by insulating material when subjected to potential difference.

Lay

1) The distance taken to complete one revolution of helically laid strands or wires around a central core. 2) The manner in which wires are helically laid into strands or strands into rope.

Length of lay

The distance required to complete one revolution of helically laid strand or wire.

Messenger Wire

Usually a high-strength bare steel wire supporting suspended aerial wire. It may be an integral part of the cable or the exterior.

Migration

1) The movement of the non-resinous plasticizer in vinyl that takes place at elevated or lowered temperatures. The migrating plasticizer from the jacket contaminates the polyethylene core of the coaxial cable and thus changes its electrical characteristics. 2) Movement of a material from one point to another. Often the movement is unwanted such as migration of contaminants around a seal in a filler.

Plasticizer

Chemical agent that is added to the stock material when compounding plastics to make it softer and more flexible.

Polyethylene

A thermoplastic material composed of ethylene polymers, commonly used as a jacketing material for outdoor cables. Derived from the polymerization of ethylene gas. Outstanding electrical properties include good moisture resistance, high dielectric strength, low dielectric constant, low dielectric loss at all frequencies, excellent resistance. Widely used for insulation on telephone signal and control of cables, high frequency electronic cables, high and low voltage power cables, line wire, neutral supported secondary and service drop cables.

Polyvinyl Chloride (PVC)

A common thermoplastic insulation and jacketing material used for wire and cable. It is composed of polymers of vinyl chloride that may be rigid or elastomeric, depending on specific formation. Produced by the combination of acetylene and hydrochloride acid. The basic polymer is a hard white infusible substance that can be rendered thermoplastic only by the addition of plasticizers. By varying the nature and quantity of the plasticizer, wide range of properties to suit a particular use can be obtained.

Resistance

Opposition by conductor to the flow of electric current. It is expressed in ohms (W).

Sheath

The combination of a metallic shield and an extruded plastic jacket applied as the outermost covering on a cable. In the absence of a shield, the extruder jacket may be designated as a sheath. Often referred to as a jacket.

Spark Test

Subjecting wire or cable to high voltage for short period while the wire is being drawn through the electrode field. Cable is passed through a metallic electrode that makes contact with the surface. The electrode is maintained at a high voltage with respect to the cable conductor. When a fault in the cable insulant enters the electrode, it is indicated by a spark. This test is performed to locate pin holes in the insulator.

Specific Gravity

The ratio of the mass of a body to the mass of equal volume of water at a specified temperature (4oC).

Stablizer

A metallic compound used for insulating purpose in some plastics maintain the physical and chemical properties of the insulation compound during processing and service life.

Strand

1) A single, uninsulated wire. 2) One of the individual wires that make up a stranded conductor. 3) An arrangement of wires helically laid about an axis or another wire or fiber center to produce a symmetrical section.

Stranded Conductor

A conductor composed of individual groups of wires twisted together to form an entire unit. A number of wires are twisted together, usually built up on a single central conductor with 6 wires in a first layer, 12 in a second, 18 in a third and so on. Most conductors therefore have 7, 19, 37, 61 or 91 wires. When there is more than one layer in a stranded conductor, the direction of lay is reversed in adjacent layers.

Strand lay

The distance advance of one strand of a spirally stranded conductor, in one turn, measured axially.

Thermoplastic

A material that can be softened repeatedly by heating and hardened by cooling through a temperature range characteristic of the plastic. In the softened state, it can be shaped by molding or extrusion. In its cooled state it retains the shape imparted when hot. It is the opposite of a thermoset material.

Thermoset

A classification of resin used for insulation that is crosslinked by a heating process known as curing. Once the plastic is cured, it cannot be re-softened or distorted from its formed shape.

Volt

A unit of electromotive force. One volt is the amount of potential required to produce current of one ampere through one ohm of resistance.

Voltage Drop

1) The difference of voltages at the two terminals of a passive impedance.
2) The difference between the voltages at the transmitting and receiving ends of a feeder, main or service. With alternating currents the voltages are not necessarily in phase and hence the voltage drop is not necessarily equal to the algebraic sum of the voltage drops along the several conductors.

 


 

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