161 Electronics Technical Information Hygroscopic: Capable of absorbing moisture from the air. Hypalon®: DuPont’s trade name for their chlorosulfonated polyethylene, an ozone- resistant synthetic rubber. Impact Tool: Device used to punch new conductor onto IDs. This tool is typically equipped with a cutting blade for either 66 or 110 blocks. Impedance: The total opposition that a circuit offers to the flow of alternating current or any other varying current at a particular frequency. It is a combination of resistance R and reactance X, measured in Ω. Impedance-Matching Transformer: A transformer designed to match the impedance of one circuit to that of another (BALUN). Impulse: A surge of unidirectional polarity. Impulse Strength: The voltage breakdown of insulation under voltage surges on the order of microseconds in duration. Impulse Test: An insulation test in which the voltage applied is an impulse voltage of specified wave shape. Incoherent Source: (fiber optic) A light source which emits wide, diffuse beams of light of many wave lengths. Index-Matching Fluid: (fiber optic) Fluid with refractive index same as fiber core; used to fill air gap between fiber ends at connectors. Index of Refraction: The ratio of light velocity in a vacuum to its velocity in a given transmitting medium. Inductance: The property of a circuit or circuit element that opposes a change in current flow, thus causing current changes to lag behind voltage changes. It is measured in henrys. Inductive Coupling: Crosstalk resulting from the action of the electromagnetic field of one conductor on the other. Infrastructure, Telecommunications: A collection of those telecommunications components, excluding equipment, that together provide the basic support for the distribution of all information within a building or campus. Insertion Loss: As measure of the attenuation of a device by determining the output of a system before and after the device is inserted into the system. Insertion Tool: A small, hand-held tool used to insert contacts into a connector. Insulated Wire: A conductor of electricity covered with a non-conducting material. Insulating Joint: A device which mechanically couples and electrically insulates the sheath and armor of contiguous lengths of cable. Insulation: A material having high resistance to the flow of electric current. Often called a dielectric in radio frequency cable. Insulation Adhesion: The degree of tightness of the insulation over the base conductor, measured in terms of force required to remove a specified length of insulation from the wire. Insulation Crimp: The area of a terminal, splice or contact that has been formed around the insulation of the wire. Insulation Grip: Extended cylinders at the rear of crimp-type contacts designed to accept the bared wire and a small length of its insulation. Insulation Piercing: A method of crimping whereby lances cut the insulation of the wires and enter into the strands to make electrical contact. Insulation Resistance: The ratio of the applied voltage to the total current between two electrodes in contact with a specific insulation, usually expressed in megΩ-M feet. Insulation System: All of the insulation materials used to insulate a particular electrical or electronic product. Integral Belt: A layer of insulation or semiconductive material applied by extrusion over two or more insulated, twisted or parallel conductors, to form a round, smooth diameter. Interconnect: A connection scheme that provides for the direct connection of individual cables to another cable or to an equipment cable without a patch cord. Interconnecting Cable: The wiring between modules, between units or the larger portions of a system. Interconnecting Wire: The physical wiring between components (outside a module), between modules, between units or between larger portions of a system or systems. Interconnection: Mechanically joining devices together to complete an electrical circuit. Interface: The two surfaces on the contact side of both halves of a multiple-contact connector which face each other when the connector is assembled. Intermediate Cross-Connect: A cross-connect between 1st level and 2nd level backbone cabling. Internal Wiring: Electronic wiring which interconnects components, usually within a sealed subsystem. Interstices: Voids or valleys between individual strands in a conductor or between insulated conductors in a multiconductor cable. Ionization Voltage (Corona Level): The minimum value of falling rms voltage which sustains electrical discharge within the vacuous or gas-filled spaces in the cable construction or insulation. Irradiation: In insulations, the exposure of the material to high energy emissions for the purpose of favorably altering the molecular structure. Jack: A plug-in type terminal widely used in an electronic apparatus for temporary connections. Jacket: An outer protective sheath over primary insulation, braids, shields, cable components or over the cable itself. In fiber optics, a covering, over a fiber, bundle of fibers or cable which protects against the environment. JAN Specification: Joint Army-Navy specification (replaced by current Military Specifications). Jumper: An assembly of twisted pairs without connectors, used to join telecommunications circuits/links at the cross connect. Junction: A point in a circuit where two or more wires are connected. Keying: The mechanical feature of a connector system that guarantees correct orientation of a connection, or prevents the connection to a jack, or to an optical fiber adapter of the same type intended for another purpose. Kynar®: Pennwalt trade name for polyvinylidene fluoride. Typically used as insulation for wire wrap wire. Lacing and Harnessing: A method of grouping wires by securing them in bundles of designated patterns. Lacquer: A liquid resin or compound applied to textile braid to prevent fraying, moisture absorption, etc. Laminated Tape: A tape consisting of two or more layers of different materials bonded together. Laser Diode: (fiber optic) A semiconductor diode that, when pulsed, a laser diode emits coherent light. Launch Angle: (fiber optic) The angle between the radiation vector and the axis of the fiber or fiber bundle. Lay: The length measured along the axis of a wire or cable required for a single strand (in stranded wire) or conductor (in cable) to make one complete turn about the axis of the conductor or cable. Layer: Consecutive turns of a coil lying in a single plane. Leaching and Non-Leaching: In a leaching wire, the plasticizer will migrate when exposed to heat. A non-leaching wire will retain its plasticizer under extreme temperature conditions and remain flexible after baking. Lead: A wire, with or without terminals, that connects two points in a circuit. Lead-Cured: A cable that is cured or vulcanized in a metallic lead mold. Lead Dress: The placement or routing of wire and component leads in an electrical circuit. Lead-in: The conductor or conductors that connect the antenna proper to electronic equipment. Leakage Current: The undesirable flow of current through or over the surface of an insulation. Life Cycle: A test to determine the length of time before failure in a controlled, usually accelerated, environment. Light Commercial Building: A building or portion thereof that is intended for use with one to four (1-4) non-residential exchange access lines per tenant. Light-Intensity Ratio: (fiber optic) Ratio of input light intensity to the output light intensity. Light Source: (fiber optic) An object capable of emitting light. In fiber optics, the light source is normally an LED or a laser. Lightguide: (fiber optic) A flexible bundle of fibers used to transmit light. Lightwave Communications: (fiber optic) Communications using light to carry the information. Limits of Error: The maximum deviation (in degrees of percent) of a thermocouple or thermocouple extension wire from standard emf-temperature to be measured. Limpness: The ability of a cable to lay flat or conform to a surface. Line Balance: The degree to which the conductors of a cable are alike in their electrical characteristics with respect to each other, to other conductors and to ground. Line Drop: A voltage loss occurring between any two points in a transmission line, due to the resonance, reactance or leakage of the line. Line Loss: The total of the various energy losses occurring in a transmission line. Line Voltage: Voltage existing in a cable or circuit. Link: An assembly of telecommunications facilities between two points, not including terminal equipment. Glossary
