CONTENTS
Note: This glossary contains many of the cable terms used throughout this book and is furnished as an aid to understand the text. The reader is encouraged to utilize the more complete definitions that may be found in the IEEE Standard Dictionary of Electrical and Electronics Terms, IEEE Standard 100-1996.
Abrasion Resistance: Ability to resist surface wear.
Accelerated Life Test: Subjecting a product to test conditions more severe than normal operating conditions, such as voltage and temperature, to accelerate aging and thus to afford some measure of probable life at normal conditions or some measure of the durability of the equipment when exposed to the factors being aggravated.
Acceptance Test: A field test made after cable system installation to demonstrate the degree of compliance with specified requirements or a test demonstrating the quality of the units of a consignment. The term “conformance test” is recommended by ANSI to avoid any implication of contractual relations.
Aging: The irreversible change of material properties after exposure to an environment for an interval of time.
Ampacity: The current carrying capacity of a cable, expressed in amperes. The current that a cable can carry under stated thermal conditions without degradation.
Ampere: The basic SI unit of the quantity of electric current. The constant current that if maintained in two straight parallel conductors of infinite length, or negligible cross section, and placed 1 meter apart in vacuum, would produce a force equal to 2 × 10−7 Newton per meter of length.
Amplitude: The maximum value of a sinusoidally varying waveform.
Annealing: The process of removing or preventing mechanical stress in materials by controlled cooling from a heated state, measured by tensile strength.
Anode: An electrode to which negative ions are attracted.
Antioxidant: A chemical additive incorporated into polyolefins to prevent degradation of materials exposed to oxygen during extrusion in the process that converts insulation materials into cable insulation over conductors.
Asymmetrical: Not identical on both sides of a central line; not symmetrical.
Attenuation: The decrease in magnitude of a signal as it travels through any transmitting medium.
Backfill: The materials used to fill an excavation, such as sand in a trench.
Basic Impulse Insulation Level (BIL): The impulse voltage that electrical equipment is required to withstand without failure or disruptive discharge when tested under specified conditions of temperature and humidity. BILs are designated in terms of the crest voltage of a 1.2 × 50 microsecond full-wave voltage test.
Bedding: A layer of material that acts as a cushion or interconnection between two elements of a device, such as the jute or polypropylene layer between the sheath and the wire armor in a submarine cable.
Bending Radius: The inner radius of a cable, such as when it is trained or being installed.
Braid: An interwoven covering having a flat configuration usually of fiber or metal.
Branching: Term used to describe the portion of the polymeric insulation that “hangs off” the main chain like a “T.”
Breakdown: Disruptive discharge through an insulation.
Bridge: A circuit that measures by balancing a number of resistances or impedances through which the same current flows.
Butt Lap: Complete turn of tape where the adjacent layers are next to each other but do not overlap.
Cable, Aerial: An assembly of one or more insulated conductors that are lashed or otherwise fastened to a supporting messenger.
Cable, Belted: A multiconductor cable having a layer of insulation over the assembled but unshielded insulated conductors.
Cable, Spacer: An aerial cable system made of covered conductors supported by insulating spacers; generally for wooded areas.
Cable, Submarine: A cable designed for crossing under bodies of water; having mechanical strength for installation and removal, and limited protection from anchors, debris, and other mechanical damage.
Cable, Tray: A rigid structure to support cables. A type of raceway normally having the appearance of a ladder. May be open at the top (or side) to facilitate changes, or be covered with a ventilated or solid cover.
Cable, Triplexed: A helical assembly of three covered or insulated conductors; sometimes with one bare conductor used as a neutral.
Cambric: A fine weave of linen, cotton, or other fiber that is used as an insulation base.
Capacitance: The storage of electricity in a capacitor. The opposition to voltage change, measured in farads.
Capacitor: Any device having two conductors separated by insulation, with the conductors having opposite electrical charges.
Capstan: A rotating drum used to pull cables or ropes by friction as they are wrapped around the drum.
Carbon Black: Elemental carbon in the form of spherical particles and aggregates, manufactured by thermal decomposition of various hydrocarbons that impart conductivity to semiconducting shields.
Catalyst: A material used to induce polymerization of monomers to convert them into polymeric insulation materials. These may be peroxides or metallocenes.
Catenary: The natural curve assumed by a completely flexible material hanging freely between two supports. A cable curing tube that has a catenary curvature.
Cathode: An electrode to which positive ions (cations) are attracted, the positive pole of a source of direct voltage.
Cellulose: A natural polymer derived from wood that is used to manufacture paper for cables.
Charge: The quantity of positive or negative ions in or on an object; unit: coulomb.
Charging Current: Current that flows in an energized cable as a result of the cable capacitance.
Circular mil: A circular mil has the equivalent area of a circle whose diameter is 0.001 inch.
Coefficient of Friction: The ratio of the tangential force needed to start or maintain relative motion between two contacting surfaces to the perpendicular force holding them in contact.
Concentric Neutral: A neutral conductor that is helically wrapped around the insulation shield of a power cable.
Conduit Fill: The percentage of cross-sectional area used in a conduit as compared with the cross-sectional area of the conduit.
Continuous Vulcanization: A system utilizing heat, and frequently pressure, to vulcanize materials after extrusion onto a conductor.
Conversion of English to Metric:
Length: |
1 mil = 0.0254 millimeters |
1 inch = 1,000 mils |
|
1 inch = 2.54 centimeters |
|
1 inch = 25.4 millimeters |
|
1,000 feet = 304.8 meters |
|
1 mile = 1,609.344 meters |
|
Area: |
1 square inch = 6.4516 × 10−4 square meters |
1,000 circular mils = 0.5067 × 10−9 square millimeters |
|
Weight: |
1 ounce = 0.028349 kilograms |
1 pound = 0.453592 kilograms |
|
Stress: |
1 kilovolt/mil = 25.4 volts/millimeter, 25.4 V/mm |
Copolymer: An insulation material composed of more than one type of monomer. Examples of copolymers are ethylene–propylene rubbers, ethylene–ethyl acrylate, and ethylene–vinyl acetate (both used as shields).
Corona: An electrical discharge caused by ionization of a gas by an electrical field.
Corona Extinction Voltage (CEV): The voltage at which partial discharge is no longer detectable within the dielectric structure when measured with instrumentation having specific sensitivity, following the application of a higher voltage to achieve corona inception.
Corona Inception Voltage (CIV): The voltage at which partial discharge is initiated within the dielectric structure with instrumentation having specific sensitivity.
Corrosion: The deterioration of a substance (usually a metal) as a result of a chemical reaction with its environment.
Cross-linking: A molecular structure where different polymer insulation material chains are joined to form a three-dimensional network. This is in contrast to where the chains are entangled together, but not joined. Cross-linking improves mechanical and physical properties.
Cross-linking Agent: A chemical that causes different polymer insulation material chains to join together. The most common type is an organic peroxide, such as dicumyl peroxide.
Crystallinity: Refers to the tendency that certain insulation materials have to “align” and form ordered regions (instead of being random). Insulation materials such as polyethylene (or polypropylene) are considered to be “semicrystalline” as portions of their polymer chains have this tendency.
Curing: A term used interchangeably with “cross-linking,” but generally within the context of processing.
Current, Charging: The current needed to bring a cable, or other capacitor, up to voltage; determined by the capacitance of the cable. After withdrawal of voltage, the charging current returns to the circuit. For AC circuits, the charging current will be 90 degrees out of phase with the voltage.
Current, Induced: Current in a conductor due to the application of a time-varying electromagnetic field.
Current, Leakage: Small amount of current that flows through insulation whenever a voltage is present. The leakage current is in phase with the voltage and is a power loss.
Density (physics): The ratio of mass to volume at a specified temperature. Term also used to describe the “tightness” of the packing of the polymer molecules in an insulation; the tighter the “packing”, the higher the density.
Dielectric Absorption: The storage of charges within an insulation (dielectric); evidenced by the decrease of current flow after application of DC voltage.
Dielectric Constant: The capacitance of a dielectric in comparison with the capacitance of a vacuum where both capacitors have identical geometry. Also referred to as permittivity or specific inductive capacitance (SIC).
Dielectric Loss: The time rate at which electrical energy is transformed into heat when a dielectric is subjected to a changing electric field; the power created in a dielectric as the result of friction produced by molecular motion in an alternating electric field.
Dielectric Strength: The maximum voltage that an insulation can withstand without breaking down; usually expressed as a gradient—volts per mil or kilovolts per millimeter.
Direction of Lay: The longitudinal direction in which the components of a cable (strands) run over the top of the cable as they recede from an observer looking along the axis of a cable; expressed as left-hand or right-hand lay.
Dissipation Factor: The energy lost when voltage is applied across an insulation due to reactive current flow. Also known as power factor and tan δ (delta).
Drain Wires: A group of small gauge wires helically applied over a semiconducting insulation shield that is designed as a path for leakage current return—as opposed to fault current or a system neutral.
Eccentricity: A measure of the centering of an item within a circular area. The ratio, expressed as a percentage, of the difference between the maximum and minimum thickness (or diameter) of an annular area.
Eddy Currents: Circulating currents induced in conducting materials by varying magnetic fields; usually considered undesirable because they represent loss of energy and create heat.
Elastomer: A term referring to rubber-like materials.
Electrical Treeing: An aging-induced defect that occurs in electrical insulation materials resulting from the application of voltage stress in the absence of water. These trees develop over a period of time significantly longer than do water trees.
Elongation: The fractional increase in length of a material as it is stressed under tension. The amount of stretch of a material in a given length before breaking.
EMI: Electromagnetic field interference.
Endosmosis: The penetration of water into a cable insulation by osmosis. Aggravated and accelerated by DC and AC voltages across the insulation where it is also known as electroendosmosis or dielectrophoresis.
Ethylene Propylene Rubber (EPR): An insulation material composed of a copolymer of ethylene and propylene.
Extrusion: The process that converts insulation material, generally in pellet form, into cable insulation over the conductor and conductor shield.
Filler: An inorganic material such as clay that may be added to a compound to improve physical properties. Fillers may be reinforcing or nonreinforcing.
Flame Retardant: A chemical additive that enhances the flame resistance of a compound.
Gel Fraction: The cross-linked portion of “cross-linked” polyethylene or EPR.
Hard Drawn: A relative measure of temper; drawn to obtain maximum tensile strength.
Hardness: Resistance to plastic deformation; stiffness or temper; resistance to scratching, abrasion, or cutting.
Heat Shrink: A term employed for certain types of joints that will shrink upon heating after they are applied in the field. The “shrinking” process is a result of the polymeric material (polyolefin) being expanded after manufacture and provided to the user in the expanded form.
High Molecular Weight: Molecular weight is a function of the number of polymer molecules in an insulation material. For example, polyethylene comprises many ethylene molecules. High molecular weight means that there are “many” such molecules, rather than a few. A low molecular weight polyethylene (not used as an insulation) would have few molecules.
Hybrid Cable System: A cable system consisting of both extruded dielectric insulation and laminated insulation.
Hypalon: Trade name for chlorosulphonated polyethylene.
Impedance (Z): The opposition to current flow in an AC circuit; impedance consists of resistance, capacitive reactance, and inductive reactance.
Installation Test: A field test conducted after cable installation but before jointing or terminating.
Insulated: Separated from other surfaces by a substance permanently offering a high resistance to the passage of energy through that substance.
Insulation Level: The thickness of insulation for circuits having ground fault detectors that interrupt fault currents within 1 minute (100% level), 1 hour (133% level), or over 1 hour (173% level).
Insulation Resistance: The measurement of DC or AC resistance of a dielectric at a specified temperature. May be either volume or surface resistivity.
Intercalated Tapes: Two or more tapes applied simultaneously so that each tape overlays a portion of the other. Example: copper and carbon shielding tapes in paper-insulated cables.
Interstices: A space between strands of a conductor or between individual phases of a multiconductor cable.
Ionization: (1) The process or the result of any process by which a neutral atom or molecule acquires charge. (2) A breakdown that occurs in gaseous phases of an insulation when dielectric stress exceeds a critical value without initiating a complete breakdown of the insulation system.
Ionization Factor: The difference between dissipation factors at two specified values of electrical stress. The lower of the two stresses is usually selected that the effect of the ionization on the dissipation factor is negligible.
Irradiation: The process of inducing cross-linking of a polymer by exposure to high energy electrons, or by gamma radiation such as Cobalt-60.
Jacket: A nonmetallic polymeric protective covering over cable insulation or shielding.
Jamming: The wedging of three or more cables in a conduit such that they can no longer be moved during cable pulling.
Jam Ratio: The ratio of the overall diameter of one cable to the inner diameter of the conduit in which they are being pulled. For three cables in a conduit, the critical jam ratio is between 2.8 and 3.2.
Lay: The axial length of one turn of the helix of any component of a cable.
Lay Length: Distance along the axis for one turn of a helical component.
Lignin: The material in wood that holds the cellulose and other components together; it is removed prior to paper manufacture due to it lossy nature.
Load Factor: The ratio of the average to the peak load over a specified period of time.
Loss Factor: Average losses divided by peak losses.
Maintenance Test: A field test made during the operating life of cable system.
Magnetic Field: The force field surrounding any current carrying conductor.
mil: Unit of measure of a conductor equal to 0.001 inch.
Monomer: A single molecule of low molecular weight used as a starting material to produce molecules of higher molecular weight (called polymers) by the process referred to as polymerization.
Mouse: A device that is attached to one end of a line and blown into a duct or pipe for use in installation of a pulling line. Usually consists of a series of rubber gaskets sized to fit the duct or pipe.
Mutual Inductance: The common property of two electric circuits whereby an electromotive force is induced in one circuit by a change of current in the other circuit.
Nominal: A term used to describe functional behavior as being within expected norms or as designed.
Ohm: The SI unit of electrical resistance; 1 ohm equals 1 volt per ampere.
Organic: Matter originating from plant or animal life; composed of chemicals—such as carbon and hydrogen.
Oscillation: The variation, usually with time, of the magnitude of a quantity that is alternatively greater or smaller than a reference.
Oscillograph: An instrument for recording or making visible the oscillations of an electrical quantity.
Osmosis: The diffusion of fluids through a membrane.
Oxidize: (1) To combine with oxygen, (2) to remove one or more electrons, (3) to dehydrogenate.
Oxygen Index: A test to rate the flammability of materials in a mixture of oxygen and nitrogen.
Ozone: A form of oxygen, O3, produced by a high electrical stress; active molecules of oxygen.
Parameter: The characteristic of a circuit from which other voltages or currents are referenced with respect to magnitude and time displacement—usually under steady-state conditions.
Partial Discharge: Decomposition of air in voids that may be present within the insulation. This leads to generation of ions and electrons that may eventually cause electrical stress and failure of the insulation.
Permeability: (1) The passage or diffusion of a vapor, liquid, or solid through a barrier without physically or chemically affecting either, (2) the rate of such passage. The passage of a liquid, gas, or vapor through a solid such as a polymer; generally reported as weight per unit time for a controlled sample size.
Permittivity: The capacitance of a dielectric in comparison with the capacitance of a vacuum where both capacitors have identical geometry. Also referred to as dielectric constant and inductive capacitance.
Phase Angle: The measure of the progression of a periodic wave in time or space from a chosen instant or position.
Phase Conductor: Any of the main conductors of a cable other than the neutral.
Phase Sequence: The order in which the successive members of a periodic wave reach their positive maximum values.
pH: An expression of the degree of acidity or alkalinity of a substance on a scale of 1 to 10. Acid is less than 7.0, neutral is 7.0, and alkaline is over 7.0.
Pig: (1) A device to isolate a portion of a pipeline to permit the local application of a test pressure, (2) an ingot of metal, such as lead.
Pilot Wire: An auxiliary insulated conductor in a circuit used for control or data transmission.
Plasticizers: Chemical agents added during compounding of certain polymeric materials (most commonly PVC [polyvinyl chloride]) to make them more flexible and pliable.
Polarization Index: The ratio of insulation resistance after two different time intervals—typically 10 minutes as compared with the measured value at 1 minute.
Polyethylene: A polymeric material employed as an insulation or jacket that comprises many ethylene molecules.
Polymer: A high molecular weight compound whose structure can usually be represented by a repetition of small units of that compound.
Polyolefin: A term that encompasses all insulation materials that are composed of carbon and hydrogen. These include polyethylene, cross-linked polyethylene, polypropylene, ethylene–propylene copolymers and terpolymers, and ethylene–alkene polymers.
Pothead: (1) A termination of a cable (potential head), (2) a device for sealing the end of a cable while providing insulated egress for the conductor or conductors. Most commonly associated with the porcelain housings for paper-insulated cables.
Power Factor (power): The cosine of the phase angle between the voltage and the current. Power factor is of interest because it is the measure of useful work. A unity power factor means that all of the current is used for useful work.
Power Factor (cable): A typical cable has a power factor of about 0.1 or less—meaning that it is almost a perfect capacitor and the majority of the current consumed by the charging current of the cable is not “useful” power. For cable purposes, the power factor is expressed as the tangent of the angle delta between the current and the voltage. For the small angles found in typical medium voltage power cables, the sin δ, tan δ, and cos Θ are essentially equal.
Power Loss: Losses due to internal cable impedances, such as the conductor I2R and the dielectric losses in the insulation. These losses create heat.
Pulling Compound: The lubricating compound applied to the surface of a cable to reduce the coefficient of friction during installation in conduits and ducts.
Pulling Eye: A device attached to the end of a cable to facilitate field connection of the pulling ropes.
Quadruplexed: Four conductors twisted together.
Relative Capacitance: The ratio of the material’s capacitance to that of a vacuum of the same configuration. Also known as specific inductive capacitance (SIC).
Reverse Lay: Reversing the direction of lay. For multiple-conductor aerial cables, a reversal in lay at a specified distance to facilitate field connections.
Rockwell Hardness: A measure of hardness of a material to indentation by a diamond or steel ball under pressure at two levels of stress.
Screen Pack: A series of metal screens used in an extruder for straining out impurities.
Semiconducting: A conducting medium where the conduction is through electrons. The resistance of these materials is generally in the range between that of conductors and insulators.
Shield: An electrically conducting layer that provides a smooth surface with the surface of the insulation. In Europe, this is called a “screen.”
Sidewall Bearing Pressure (SWBP): The normal force on a cable under tension at a bend. This is a force that tends to flatten or crush the cable and is usually given as an allowable force for a given distance.
Silane: A silicone-based monomer that can be used to impregnate polyethylene or cross-linked polyethylene insulated cables and react with water, and undergoes in-situ cross-linking.
Skin Effect: The tendency of current to crowd toward the outer surface of a conductor that increases with conductor diameter and frequency of the applied current.
Sol Fraction: The uncross-linked portion of “cross-linked” polyethylene or EPR.
Specific Inductive Capacitance: The capacitance of a dielectric as compared with the capacitance of a vacuum where both capacitors have identical geometry. Also referred to as dielectric constant and permittivity.
Strand, Sector: A stranded conductor formed into sectors of a circle to reduce the overall diameter of the cable.
Strand, Segmental: A stranded conductor formed of sectors that are insulated from one another to reduce the AC resistance of the conductor.
Strand, Unilay: A stranded conductor having a unidirectional lay of the various wires. Frequently used in low voltage power cables.
Stress Relief Cone: A mechanical component of a termination to reduce electrical stress levels on a shielded cable, originally in the shape of a cone.
Stripping Strength: Refers to the ease (or lack of) when the insulation shield is “peeled” from the insulation surface.
Tandem Extrusion: Extruding two or more layers on a conductor where the extruders are in close proximity to one another.
Thermoplastic: A polymeric insulation material that possesses the property of softening when heated.
Thermosetting: Polymeric insulation materials that, upon curing (cross-linking), undergo an irreversible chemical and physical property change as a result of the cross-linking process. Thermoset materials cannot be refabricated.
Tinned: A strand having a thin coating of pure tin or an alloy of tin and lead. Used over copper to reduce the effect of sulfur from certain rubber compounds and to facilitate solder connections. Many aluminum connectors are also tin-plated to minimize the formation of aluminum oxide.
Treeing: An aging-induced defect in insulation materials that imparts a tree-like appearance to the affected region. Treeing is generally referred to as electrical treeing or water treeing.
Triplexed: Three conductors or cables that are twisted together.
Voltage Rating: The designated maximum permissible phase-to-phase AC (or direct current) voltage at which a cable is designed to operate.
Vulcanize: To cure (cross-link) by chemical reaction. Produces changes in the physical properties of the material by the reaction of an additive (originally sulfur) at an elevated temperature. A term initially applied to elastomers.
Water Tree: An aging-induced defect in insulation materials that results from the application of voltage stress in the presence of water. This may result at normal operating stress over periods of time that are relatively short as compared with electrical treeing.
A |
Common abbreviation for ampere |
AC |
Alternating current, an electric circuit that periodically reverses direction |
ACLT |
Accelerated cable life test |
AWG |
American Wire Gauge |
AWTT |
Accelerated water treeing test |
BIL |
Basic impulse insulation level |
BR |
Butyl rubber (isobutylene–isoprene copolymer) |
CPE |
Chlorinated polyethylene rubber |
CSPE |
Chlorosulfonated polyethylene rubber (Hypalon) |
CV |
Continuous vulcanization |
DAC |
Damped AC voltage |
AC |
Direct current |
DF |
Dissipation factor, also tan δ (delta) |
DiBenzo GMF |
Quinone dioxime dibenzoate |
DOE |
U.S. Department of Energy |
EC |
Alloy designation for aluminum electrical conductors |
EDG |
Emergency diesel generator |
EPDM |
Ethylene propylene diene methane. An insulation material composed of three monomers, ethylene, propylene, and a third monomer generally referred to as a diene-monomer |
EPR |
An insulation material composed of a copolymer of ethylene and propylene |
EPRI |
Electric Power Research Institute |
EPR |
Ethylene propylene rubber |
FLECTOL H |
Polymerized trimethyl quinoline antioxidant |
GMF |
Quinone dioxime |
GR-S |
Government Rubber-Synthetic, now SBR, styrenebutadiene |
HDPE |
High-density polyethylene |
hi-pot |
High potential |
HMWPE |
High molecular weight polyethylene |
HPFF |
High-pressure fluid filled cable |
HTK |
A Kerite Company insulation polymer designation |
Hz |
Hertz, number of cycles per second |
ICEA |
Insulated Cable Engineers Association |
IEC |
International Electrotechnical Commission |
IEEE |
Institute of Electrical and Electronics Engineers |
IET |
Institution of Engineering and Technology (UK), formerly IEE |
INPO |
Institute for Nuclear Power Operations |
IPCEA |
Prior to 1979: Insulated Power Cable Engineers Association |
IRC |
Isothermal relaxation current |
kcmil |
Thousand circular mils, formerly MCM |
kV |
Kilovolts |
LCO |
Limiting Condition for Operation |
LDPE |
Low-density polyethylene |
LER |
Licensee event report |
LOCA |
Loss of coolant accident |
LPFF |
Low-pressure fluid filled cable |
MCM |
Thousands of circular mils (also KCM), an older term for conductor area |
mil |
1/1,000th of an inch |
MBTS |
Mercapto Benzo Thiazole |
mm |
Millimeter. Unit of measure equal to 0.001 meter |
MV |
Medium voltage, generally 5 to 46 kV |
MW |
Megawatt, equal to 1,000 kilowatts and 1,000,000 watts |
NEC |
National Electrical Code |
NEI |
Nuclear Energy Institute |
NEMA |
National Electrical Manufacturers Association |
Nordel |
DuPont trade name for EPR rubbers |
NPRDS |
Nuclear Plant Reliability Data System |
NRC |
U.S. Nuclear Regulatory Commission |
NRR |
Nuclear Reactor Regulation |
pC |
Pico coulomb |
PD |
Partial discharge |
PDEV |
Partial discharge extinction voltage |
PDIV |
Partial discharge inception voltage |
PE |
Polyethylene |
PILC |
Paper-insulated, lead covered cable |
PSE |
Plant support engineering |
PVC |
Polyvinyl chloride |
SSC |
System, structure, or component |
SR 350 |
Sartomer 350 monomer |
tan δ |
tangent δ (a loss factor of insulation) |
TDR |
Time domain reflectometry |
TR-XLPE |
Tree-retardant XLPE |
UD |
Underground distribution |
UL |
Underwriters Laboratory |
URD |
Underground residential distribution |
VO, also UO |
Phase-to-ground voltage |
Vistalon |
EXXON trade name for EPR rubbers |
XLPE |
Cross-linked polyethylene |
ZnO |
Zinc Oxide |
μs |
Microsecond |