IEEE Std 100-199?“
`
`The IEEE Standard Dictionary of
`Electrical and Electronics Terms
`
`Sixth Edition
`
`Standards Coordinating Committee 10, Terms and Definitions
`Jane Radatz, Chair
`
`This standard is one of a number of infolmation technology dictionaries being developed by standards
`organizations accredited by the American National Standards Institute. This dictionary was developed
`under the sponsorship of voluntary standards organizations, using a consensus—based process.
`
`ISBN 1.-55°13?-B33-la
`
`1|
`
`9 781559 378338
`
`iiilu
`
`
`
`1
`
`SAMSUNG 1010
`
`

`
`Introduction
`
`Since the first edition in 1941 of the American Standard Definitions of Electrical Terms, the work now
`known as IEEE Std 100, The IEEE Standard Dictionary of Electrical and Electronics Terms, has evolved
`into the unique compendium of terms that it is today.
`
`The current edition includes all terms defined in approved lEEE standards through December 1996. Terms
`are categorized by their technical subject area. They are also associated with the standards or publications
`in which they currently appear. In some cases, terms from withdrawn standards are included when no
`current source can be found. Earlier editions of IEEE Std 100 included terms from sources other than
`IEEE standards, such as technical journals, books, or Conference proceedings. These terms have been
`maintained for the sake of consistency and their sources are listed with the standards in the back of the
`book.
`
`The practice of defining terms varies from standard to standard. Many working groups that write standards
`prefer to work with existing definitions, while others choose to write their own. Thus terms may have
`several similar, although not identical, definitions. Definitions have been combined wherever it has been
`possible to do so by making only minor editorial changes. Otherwise, they have been left as written in
`the original standard.
`
`Users of IEEE Std 100 occasionally comment on the surprising omission of a_ particular term commonly
`used in an electrical or electronics field. This occurs because the terms in IEEE Std 100 represent only
`those defined in the existing or past body of IEEE standards. To respond to this, some working groups
`obtain authorization to create a glossary of terms used in their field. All existing, approved standard
`glossaries have been incorporated into this edition of IEEE Std 100, including the most current glossaries
`of terms for computers and power engineering.
`
`IEEE working groups are encouraged to refer to IEEE Std 100 when developing new or revised standards
`to avoid redundancy. They are also encouraged to investigate deficiencies in standard terms and create
`standard glossaries to alleviate them.
`
`The sponsoring body for this document was Standards Coordinating Committee 10 on Definitions
`(SCCIO), which consisted of the following members:
`
`John W. Balde
`Arthur Ballato
`Bruce Barrow
`William Carey
`Frank A. Denbrock
`Jay Forster
`
`Jane Radatz, Chair
`
`Chris Heegard
`John Horch
`I. L. Koepfinger
`Allen H. Meitzler
`Frank D. Myers
`David E. Roberts
`
`F. A. Saal
`Ralph M. Showers
`Edward N. Skomal
`Kenneth L. Swinth
`Raymond S. Turgel
`Edward F. Vance
`
`2
`
`

`
`When the IEEE Standards Board approved this standard on 10 December 1996, it had the following
`membership.
`
`Richard J. I-Iolleman, Vice Chair
`Donald C. Lorrghry, Chair
`Andrew G. Salem, Secretary
`
`Gilles A. Baril
`Clyde R. Camp
`Joseph A. Cannatelli
`Stephen L. Diamond
`Harold E. Epstein
`Donald C. Fleckenstein
`Jay Forster*
`Donald N. Heirman
`Ben C. Johnson
`
`*Member Emeritus
`
`E. G. “Al” Kiener
`Joseph L. Koepfinger*
`Stephen R. Lambert
`Lawrence V. McCall
`L. Bruce McClung
`Marco W. Migliaro
`Mary Lou Padgett
`John W. Pope
`
`Jose R. Ramos
`Arthur K. Reilly
`Ronald H. Reimer
`Gary S. Robinson
`Ingo Riisclr
`John S. Ryan
`Chee Kiow Tan
`Leonard L. Tripp
`Howard L. Wolfman
`
`Also included are the following nonvoting IEEE Standards Board liaisons:
`
`Satish K. Aggarwal
`Alan H. Cookson
`
`Chester C. Taylor
`
`Kim Breitfelder (1995-present), IEEE Std 100 Editor
`Stephen Huffman (1993-1995), IEEE Std 100 Editor
`
`Assistance was provided by the IEEE Standards editorial staff.
`
`How to use this dictionary
`
`The terms defined in this dictionary are listed in letter—by-letter alphabetical order. Spaces are ignored in
`this style of alphabetization, so cable value will come before cab signal. Descriptive categories associated
`with the term in earlier editions of IEEE Std 100 will follow the term in parentheses. New categories
`appear after the definitions (see Categories, below), followed by the designation of the standard or stan-
`dards that include the definition. If a standard designation is followed by the letter s, it means that edition
`of the standard was superseded by a newer revision and the term was not included in the revision. If a
`designation is followed by the letter w, it means that edition of the standard was withdrawn and not
`replaced by a revision. A bracketed number refers to the non—IEEE standard sources given in the back
`of the book.
`
`Acronyms and abbreviations are no longer listed in a separate section in the dictionary; rather, they are
`incorporated alphabetically with other terms. Each acronym or abbreviation refers to its expanded term,
`where it is defined. Acronyms and abbreviations for which no definition was included in past editions
`have been deleted from this edition of IEEE Std 100.
`
`Abstracts of the current set of approved IEEE standards are provided in the back of the book. It should
`be noted that updated information about IEEE standards can be obtained at any time from the IEEE
`Standards World Wide Web site at http://standards.ieee.org/.
`
`fiategories
`
`The category abbreviations that are used in this edition of IEEE Std 100 are defined below. This infor-
`rnrrtion is provided to help elucidate the context of the definition. Older terms for which no categor'y could
`be fountl have had the category “Std100” assigned to them. Note that terms from sources other than IEEE
`stzrrrdttrds. such as the National Electrical Code® (NEC®) or the National Fire Protection Association,
`may not be from the most recent editions; the reader is cautioned to check the latest editions of all sources
`for the most up~to~da1:e terminology.
`i\
`
`3
`
`

`
`supplier
`
`id to pro-
`oach to a
`ng of the
`D)
`[127]
`the signal
`3f a train.
`3)
`[119]
`hting cir-
`
`[119]
`3)
`iration of
`1 runway
`approach
`))
`[127]
`clocking
`ified dis-
`that pre-
`time in-
`its most
`or elec-
`ill in the
`aspect to
`)ute. See
`1)
`[119]
`tion dur-
`or other
`
`2-1983w
`rt of die
`‘landing
`:t0uches
`Z-1983w
`reach to
`-)
`[119]
`ches the
`47-1992
`d means
`ned pro-
`[options
`s. There
`
`-2- 1 993
`.g privi-
`ralls and
`vileges.
`
`Sb-1995
`entative
`uther as-
`used as
`shift re-
`require-
`l6-1995
`f Mines
`assem-
`ipment.
`:he per-
`
`[119]
`one or
`condi-
`he type
`l-19823
`iority.
`[119]
`
`1-1993
`
`iipment
`:e qual-
`aund to
`‘vice to
`l-l987r
`
`ll
`
`j
`
`approximate value
`
`43
`
`arc, clockwise
`
`approximate value (metric practice) A value that is nearly but
`not exactly correct or accurate.
`(QUL) 268-19825
`A Programming Language An interactive programming lan-
`guage with a concise syntax that is well—suited for solving
`mathematical problems requiring intricate vector or matrix
`manipulations. Notes: 1. Requires a special keyboard config-
`uration due to its extended character set. 2. Standardized by
`ISO/IEC.
`(C) 610.13-1993
`APSE See: Automatic Programming and Scaling of Equations.
`APS Instance An instantiation of an APS API service provider,
`including the APS environment and internal state informa-
`tion.
`(C/PA) 1351-1994
`APT See.‘ automatic programmed tools; Automatically Pro-
`grammed Tools.
`arbiter (1) A functional module that accepts bus requests from
`requester modules and grants control of the data transfer bus
`(DTB) to one requester at a time.
`(BA/C) 1014-1987
`(2) When implementing the serial arbitration method, the ar-
`biter module accepts requests for the DTB from requesters
`and grants control of the DTB to one requester at a time.
`There is one and only one active arbiter in the serial arbitra-
`tion scheme, and it is always located in slot 1. An arbiter is
`not required in the parallel arbitration method.
`(C/MM) 1096-1988
`(3) The module that is perfonning the arbitration.
`(BA/C) 896.4-1993
`arbitrary sequence computer A computer in which each in-
`struction explicitly specifies the location of the next instruc-
`tion to be executed. Contrast: consecutive sequence com-
`puter. See also: nonsequential computer.
`
`(C) 610.10-1994
`arbitrated message (1) A number broadcast on the arbitrated
`message bus lines to all modules on the bus.
`(BA/C)
`10857-1994, 8963-1993
`(2) An event number broadcast on the arbitrated message bus
`lines to all modules on the bus.
`(BA/C) 896.4-1993
`arbitration (1) The process of determining which requesting
`device will gain access to a resource.
`(C/MM) 959-19881‘
`(2) The means whereby masters compete for control of the
`bus and the process by which a master is granted control of
`the bus.
`(C/MM)
`1000-19871‘
`(3) A collection of mechanisms that allow masters to access
`the bus without conflicting with each other.
`(C/MM) 1196-1987
`(4) The process of selecting the next bus master.
`(BA/C)
`1014.1—l994, 10857-1994, 8963-1993.
`8964-1993
`(S) The process by which nodes compete for ownership of
`the bus. The cable environment uses a hierarchical point—to—
`point algorithm, while the backplane environment uses the
`bit-serial process of transmitting an arbitration sequence. At
`the completion of an arbitration contest, only one node will
`be able to transmit a data packet.
`(C/ MM)
`1394-1995
`arbritration bus One of the four buses provided by the back-
`plane. This bus allows an arbiter module and several requester
`modules to coordinate use of the DTB.
`
`(BA/C) 1014-1987
`arbitration clock rate The rate used to define a number of
`timing requirements within the backplane physical layer. It is
`49.152 MHz X 100 ppm, regardless of the backplane inter-
`face technology.
`(C/MM) 1394-1995
`arbitration contest This is the core mechanism to resolve bus
`ownership between one or more competing masters. It takes
`two bus periods.
`(C/MM) 1196-1987
`arbitration cycle (1) (FASTBUS acquisition and control) The
`process by which the next master to be granted bus mastership
`is detemiined. It is initiated by the arbitration timing control-
`ler and is complete when the winning master assumes bus
`mastership.
`960-1993
`(2) (VSB) A cycle that is initiated by the active requester in
`response to a bus request, after its associated active master
`no loqggg needs the bus. This cycle is used to select the master
`
`that will be granted use of the DTB. If the active requester
`detects a request for the bus, and if its associated master no
`longer needs the bus, it initiates an arbitration cycle. During
`the arbitration cycle. all contending requestc1‘s drive an arbi-
`tration ID on the bus. This ID is a combination of the geo-
`graphical address of the board that is supplied by the back-
`plane slot, and a priority code that is supplied by user-defined
`on-board logic. At the end of the arbitration cycle, one of the
`contending requcsters becomes the active requester.
`(C/MM)
`1096-1988
`arbitration locked sequence A sequence of operations by one
`master, directed to a number of different primary addresses,
`which is not interruptable by any other master because the
`originating master does not allow bus arbitration to take place.
`960- 1993
`
`arbitration operation The bus operation in which agents at-
`tempt to gain exclusive access to the parallel system bus.
`(C/MM)
`1296-19875
`arbitration reset gap The minimum period of idle bus that has
`to occur after a source using the fairness protocol has won an
`arbitration contest before it can once again compete for bus
`mastership. This is longer than a normal subaction gap.
`(C/MM)
`1394-1995
`arbitration sequence For the backplane environment, a set of
`bits transmitted by nodes that wish to transmit packets that is
`used to determine which node will be able to transmit next.
`(C/MM)
`1394-1995
`arbitration signal Bidirectional signal exchanged between
`nodes during arbitration. One of the PDUs for the physical
`layer (the other is the data bit).
`(C/MM)
`1394-1995
`arbitration timing control (ATC) Logic associated with each
`segment for the purpose of supervising and generating the
`arbitration control signals, run/halt control, and broadcast
`system handshake. (This is part of the ancillary logic.)
`960-1993
`
`are (1) (A) (computer graphics) A continuous portion of a
`circle. (B) (computer graphics) A finite set of pixels repre-
`senting a portion of a curve.
`
`illustrations of are
`
`(C) 6104-1990
`(2) (overhead power lines) A continuous luminous discharge
`of electricity across an insulating medium, usually accom-
`panied by thc partial volatilization of the electrodes.
`(PE/T&D) 539-1990
`(3) A discharge of electricity through a gas, normally char-
`acterized by a voltage drop in the immediate vicinity of the
`cathode approximately equal to the ionization potential of the
`gas. See also.‘ gas tube.
`l6l—197lw, 539-1990
`(ED/PE/T&D)
`arc-back (gas tube) A failure of the rectifying action, which
`results in the How ofa principal electron stream in the reverse
`direction, due to the fomiation of a cathode spot on an anode.
`See also.‘ gas tube; rectification.
`(ED)
`l6l—197lw
`arc cathode (gas tube) A cathode whose electron emission is
`self—sustaining, with a small voltage drop approximately
`equal to the ionization potential of the gas.
`(Stdl00)
`[84]
`are chute (of a switching device) A structure affording a con-
`fined space or passageway, usually lined with arc-resisting
`material, into or through which an arc is directed to extinction.
`(PE/SWG) C37.100-1992
`arc, clockwise (numerically controlled machines) An are gen-
`erated by the coordinated motion of two axes in which cur-
`vature of the path of the tool with respect to the workpiece is
`clockwise when viewing the plane of motion in the negative
`direction of the perpendicular axis.
`(IA)
`[61]
`
`4
`
`

`
`st duration
`
`ipletion re-
`(IM)
`[40]
`f a quantity
`hat exceeds
`tude of this
`y long that
`e the result
`t reference.
`points in a
`JSI be mea-
`ctrical rep-
`riable such
`
`[321
`(Sr)
`;e in inten-
`erved from
`211-19775
`at does not
`.' decollate.
`l, often by
`0.10-I994
`
`the the po-
`.02-5-1995
`f the same
`02-5-1995
`’ the same
`02-5-1995
`I the burst
`pper burst
`.57-l964w
`
`dio noise)
`11 stage of
`th electric
`ption volt-
`of velvet-
`. The cur-
`d may last
`539-1990
`The time
`:st magni-
`lso: burst;
`S7—l964w
`1e interval
`rantity ex-
`zxcursions
`individual
`f selected
`; equal to
`burst has
`elow, are
`
`rat is slid
`the lower
`the burst
`:quals the
`tferences.
`‘osses the
`then been
`
`the win-
`window.
`t leading-
`
`ar proce-
`)sition in
`The left-
`
`burst duty factor
`
`'
`
`l 17
`
`bus clock cycle
`
`upper burst reference, U; lower burst reference, L; long-
`time average power, P.
`See also.‘ burst.
`
`SAFEGUARD
`INTERVAL
`
`UPPER BURST
`REFERENCE
`
`LOWER BURST
`REFERENCE
`
`MAGNITUDE
`
`MAGNlTUDE
`
`MAGNITUDE
`
`MAGNlTUDE
`
`Plot of instantaneous magnitude versus time to illustrate
`terms used in defining a burst.
`burst duration
`
`[32], 257-1964w
`(SP)
`burst duty factor (audio and electroacorrstics) The ratio of the
`average burst duration to the average spacing. Note: This is
`equivalent to the product of the average burst duration and
`the burst repetition rate. See also: burst.
`[32], 257-l964w
`(SP)
`burst error In data communications, a series of consecutive
`errors in data transmission that tend to be grouped together,
`with a longer time interval separating multiple bursts
`(C) 610.7-i995
`burst fall-off interval (arrdio and electroacoustics) The time
`interval between the instant at which the upper burst reference
`is last equaled and the burst trailing edge time. See also: burst.
`(SP)
`[32], 257—I964w
`burst flag (television) A keying or gating signal used in forming
`the color burst from a chrominance subcarrier source. See
`also: television.
`(BT)
`[34]
`burst gate (television) A keying or gating device or signal used
`to extract the color burst from a color picture signal. See also.’
`television.
`(BT)
`[34]
`burst keying signal See: burst fiag; television.
`burst leading-edge time (audio and electruacoustics) The in-
`stant at which the instantaneous burst magnitude first equals
`the lower burst reference. See also: burst.
`[32], 257—1964w
`(SP)
`burst measurements See: energy-density spectrum.
`burst mode A mode of transmission by which a system can
`send a burst of data at higher speed for some period of time.
`(C) 6107-1995
`burst-quiet interval (audio and electroacoustics) The time in-
`terval between successive bursts during which the instanta-
`was
`
`the upper burst reference.
`neous magnitude does not equal
`(SP)
`[32], 257-196-4w
`See also: burst.
`burst repetition rate (audio and electroacoustics) The aver-
`age number of bursts per unit of time. See also: burst.
`(SP)
`[32], 257-l964w
`burst rise interval (audio and electroacoustics) The time in-
`terval between the burst leading-edge time and the instant at
`which the peak burst magnitude occurs. See also: burst.
`(SP)
`[32], 257-l964w
`burst safeguard interval (audio and electroacoustics) A time
`interval of selected length during which excursions below the
`lower burst reference are neglected; it is used in determining
`those instants at which the lower burst references are first and
`last equaled during a burst. See also: burst.
`[32], 257-l964w
`(SP)
`burst spacing (audio and electroacoustics) The time interval
`between the burst
`leading-edge times of two consecutive
`bursts. See also.‘ burst.
`(SP)
`[32], 257—l964w
`burst trailing-edge time (audio and electroacoustics) The in-
`stant at which the instantaneous burst magnitude last equals
`the lower burst reference. See also: burst.
`[32], 257-l964w
`(SP)
`burst train (audio and electroacoustics) A succession of sim-
`ilar bursts having comparable adjacent burst-quiet intervals.
`See also: burst.
`(SP)
`[32], 257—l964w
`bus (1) A three-phase junction common to two or more ways.
`(PE/SWG) C37.7l-l984r
`(2) (microcomputer system bus) (signals and paths) A sig-
`nal line or a set of lines used by an interface system to connect
`a number of devices and to transfer data.
`(C/IM/MM)
`i000-19871‘, 488.1-l987r, 696-l983w, 796-
`l983r, 959-l988r
`(3) One or more conductors used for transmitting signals or
`power from one or more sources to one or more destinations.
`(C) 162-l963w
`(4) (simple 32-bit backplane bus) A set of signal litres to
`which El number of devices are connected and over which
`information is transferred between them.
`[196-1987
`(C/MM)
`(5) (hydroelectric power plants) A conductor or group of
`electrical conductors serving as common connections be-
`tween circuits, generally in the form of insulated cable, rigid
`rectangular or round bars, or stranded overhead cables held
`under tension.
`(PE) 1020-l988r
`(6) The concatenation of the ll‘ClI1SmlSSl0Ii
`links between
`nodes and the data path within nodes that provides unidirec-
`tional transport of the digital bit stream from the Head ofBus
`function past the access unit (A U) of each node to the end of
`bus.
`(C/LM) 8802-64994
`(7) One or more conductors that are used for the transmission
`of signals, data, or power. See also.‘ address bus; bidirectional
`bus; control bus; data bus; data chain bus; memory bus; time-
`multiplexed bus.
`(C) 61010-1994
`(8) A conductor, or group of conductors,
`that serves as a
`common connection for two or more circuits.
`(PE/SWG) C37.lOO-1992
`bus bar A common metallized region that connects the individ-
`ual interdigital transducer fingers and provides a contact area
`for external circuit connection via bonding or other means.
`(UFFC)
`1037- 1992
`bus-based architecture A computer architecture in which the
`components such as processors, peripheral devices and mem-
`ory are interconnected by one or more busses. Contrast: non-
`bus-based architecture.
`(C) 610. l0-1994
`bus bridge A bus bridge is an interconnect between two or more
`buses that provides signal and protocol translation from one
`bus to another. The buses may adhere to different bus stan-
`dards for mechanical, electrical, and logical operation (such
`as a bus bridge from Futurebus+ to VMEbus or to Multi-
`bus 11).
`10857-1994, 8962-1991, 8963-1993, 8964-1993
`(BA/C)
`bus clock cycle An amount of time equal to one bus clock pe-
`riod, nominally l0O ns.
`(C/MM)
`i296-l987s
`
`5
`
`

`
`bus cycle
`
`bus cycle (1) (general system) (microcomputer system bus)
`The process whereby digital signals effect the transfer of data
`bytes or words across the interface by means of an interlocked
`sequence of control signals. lnterlocked denotes a fixed se-
`quence of events in which one event must occur before the
`next event can occur.
`(C/MM) 796~l983f
`(2) (696 interface devices) (signals and paths) The basic
`sequence of electrical events required to complete a transfer
`of data on the bus, A bus cycle contains at least three bus
`states.
`(C/MM) 696-l983w
`bus-dependent (I) A term used to describe parameters that may
`vary among different bus standards, but are defined by them.
`Although the CSR Architecture may constrain the definition
`of these fields, their detailed definition is provided by the
`appropriate bus standard.
`(C/ MM)
`1212-19915
`(2) This term is used to describe technology-dependent pa-
`rameters. Although the CSR Architecture may specify the size
`and address of these parameters, their format and definition
`is provided by the appropriate bus standards.
`(BA/C) 896.4-1993
`(A) A device capable of providing sufficient
`bus driver
`current to drive all loads connected to a bus. See also: bus
`slave. (B) A device that controls access to a bus.
`(C) 610.10-1994
`Bus Error BSE bit A bit in the Slave Status register of every
`S-module that is set by the S-module when a Bus Error is
`recorded in the Bus Error register.
`(C/TT)
`1 1495-1995
`Bus Error register A status register that is required to be im-
`plemented in the MTM-Bus interface circuitry of every S-
`rnodule. Bits in this register provide the S-module with the
`ability to record error conditions associated with message
`transmission. The register may be interrogated by the M-mod-
`ule. Some bits in the register are reserved for application-
`specific uses.
`(C/Tl")
`ll49.5-1995
`bushing (1) (electrical) (rotating machinery) Insulator to per-
`mit passage of a lead through a frame or housing.
`
`[9]
`(PE)
`(2) An insulating structure including a through conductor,
`or providing a passageway for such a conductor, with pro-
`vision for mounting on a barrier, conducting or otherwise, for
`the purpose of insulating the conductor from the barrier and
`conducting current
`from one side of the barrier
`to the
`other.
`
`(NESC/PE/SWG) 62-1995, C2-1997, C37.l00-1992,
`C57.l2.80—1978r
`
`(Std100)
`(3) (relay) See also: relay spring stud.
`bushing condenser The component within a capacitive graded
`bushing in which the grading element is embedded in the
`major insulation.
`(PE) C57.l9.03-1996
`bushing insert (separable insulated connectors) A connector
`component intended for insertion into a bushing well.
`(PE/T&D) 386-I995
`bushing potential tap (outdoor apparatus bushings) An in-
`sulated connection to one of the conducting layers of a bush-
`ing providing a capacitance voltage divider to indicate the
`voltage applied to the bushing.
`(PE) 21-1976
`bushing, rotor See: rotor bushing.
`bushings for combined voltage application A bushing applied
`to the valve winding side of a converter transfomicr or a bush-
`ing applied to the converter transfomier side of a dc converter
`valve. This bushing is exposed to a large ac stress superim-
`posed on a dc bias.
`(PE) C57.l9.03—l996
`bushings for pure DC application A bushing applied to thedc
`side of a dc converter valve or a bushing applied on a dc
`smoothing reactor. This bushing is exposed to dc stress with
`a small AC ripple.
`(PE) C57.19.03-1996
`bushing tap (panial discharge measurement
`in liquid—f1lled
`power trzrnsfomiers and shunt reactors) Connection to :1 ca-
`pacitor foil in a cap-acitively graded bushing designed for volt-
`‘fage or power factor measurement that also provides a con-
`venient connecting point for partial discharge measurement.
`,’l'—‘ho tap-to-phase capacitance is generally designated as C,
`
`bus line
`
`and the tap-to-ground capacitance is designated as C2. See
`also.‘ bushing potential tap; bushing test tap; capacitance.
`'
`(PE/SWG)
`[I25], 1291-1993, C57.ll3-1988s
`bushing test tap (1) (outdoor apparatus bushings) An insu-
`lated connection to one of the conduction layers of a bushing
`for the purpose of making insulation power factor tests.
`(PE) 21-1976
`(2) A connection to one of the conducting layers of a capac-
`itance graded bushing for measurement of partial discharge,
`power factor, and capacitance values.
`
`(PE) C57. 1 9.03-1996
`bushing type current transformer A current transformer (CT)
`that has an annular core with a secondary winding insulated
`from and permanently assembled on the core but has no pri-
`mary winding or insulation for a primary winding. This type
`of CT is for use with a fully insulated conductor as a primary
`winding. A bushing type ct
`is usually used in equipment
`where the primary conductor is a component pan of other
`apparatus. Note: This type of ct has very low leakage flux
`and is also known as a Low Inductance Type CT.
`(PE) C37.l 10-1996. C57.12.80-l978r, C57.l3-1993
`bushing voltage tap A connection to one of the conducting
`layers of a capacitance graded bushing providing a capaci-
`tance voltage divider. Note: Additional equipment can be de-
`signed, connected to this tap and calibrated to indicate the
`voltage applied to the bushing. This tap can also be used for
`measurement of partial discharge, power factor and capaci-
`tance values.
`(PE) C57.l9.03-1996
`
`bushing well (separable insulated conductors) An apparatus
`bushing having a cavity for insertion of a connector compo-
`nent, such as a bushing insert.
`(PE/T&D) 386-1995
`bus-ID A 10-bit number uniquely specifying a particular bus
`within a system of multiple interconnected buses.
`1394-1995
`(C/MM)
`busied A status indication returned in an echo packet that in-
`dicates to the sender that the send packet was not accepted
`(and was discarded), probably because there was no room in
`the destination queue. The sender should retransmit
`the
`packet later.
`(C / MM)
`1596-1992
`bus implementation conformance statement (BICS) This is a
`completed BICS pro forma questionnaire.
`(BA/C) 896.4-1993
`
`bus implementation conformance statement pro forma
`(BICS pro forma) A questionnaire that lists implementation
`capabilities.
`(BA/C) 896,4-1993
`bus implementation extra information for testing (BIXIT) A
`Completed BIXIT pro fonna.
`(BA/C) 896.4-1993
`bus implementation extra information for testing pro forma
`(BIXIT pro forma) This questionnaire provides extra infor-
`mation about the module that might be necessary to configure
`and perform the tests.
`(BA/C) 896.4-1993
`business data processing The use of computers for processing
`information to support the operational, logistical, and func-
`tional activities performed by an organization.
`(C) 6102-1987
`
`business graphics The use of computer graphics to display busi-
`ness data; for example, bar charts, histograms, pie charts.
`(C) 610.6-1991
`
`information
`
`business information system See: management
`system.
`bus interface unit (BIU) The logic on a module that converts
`bus signals to and from signals that are compatible with the
`functional logic of the module.
`(BA/C) 8963-1993
`bus line (1) (railways) A continuous electric circuit other than
`the electric train line, extending through two or more vehicles
`of a train, for the distribution of electric energy. See also:
`multiple—unit control.
`(EEC/PE)
`[119]
`(2) Signal transmission line, that may be driven by several
`modules simultaneously using drivers with wire-OR capabil-
`ity. Therefore, zr signal carried by a bus line is the combination
`
`6
`
`

`
`continuum
`
`continuum Sec: baseline.
`contour analysis In optical character recognition, a technique
`for locating the outline of a character by searching around its
`exterior edges with a spot of light.
`(C) 6102-1987
`contoured beam antenna A shaped-beam antenna designed in
`such a way that when its beam intersects a given surface, the
`lines of equal power flux density incident upon the surface
`form specified contours. See also: footprint.
`
`145-1993
`(AP)
`contour encoding An image compression technique in which a
`region that has a constant gray level is encoded by specifying
`only its border.
`(C) 610.4-1990
`contouring control system (numerically controlled ma-
`chines) A system in which the controlled path can result from
`the coordinated, simultaneous motion of two or more axes.
`(EEC)
`[74]
`contract (1) (diode-type camera tube) The ratio of the differ-
`ence between the peak and minimum values of irradiance to
`the peak irradiance of an image or specified portion of an
`image.
`
`C = Q3 X 100 (percent)
`Er
`
`(ED) 503—l978w
`(2) A legally binding document agreed upon by the customer
`and supplier. This includes the technical and organizational
`requirements, cost, and schedule for a product. A contract
`may also contain informal but useful information such as the
`commitments or expectations of the parties involved.
`(C/SE) 830-1993
`(3) A binding agreement between two parties, especially en-
`forceable by law or similar internal agreement wholly within
`an organization, for supply of service or for the supply, de-
`velopment, production, operation, or maintenance of a soft-
`ware product.
`(C/SE)
`1062-1993
`contract curve (rotating electric machinery) A specified ma-
`chine characteristic cuive that becomes part of the contract.
`(PE) 11-l980r
`contract demand (power operations) The demand that the
`supplier of electric service agrees to have available for de-
`livery.
`(PE) 858-1993
`contractor (1) (hydroelectric power plants) A device used for
`repetitive opening and closing operation of an electiic circuit,
`and that has load-current interrupting capability. It has no
`fault-current interrupting capability.
`(PE) 1020-l988r
`(2) (metal transmission structures) See also: constructor.
`(PE/T&D) 951—l988s
`(3) (power and distribution transformers) A device for re-
`peatedly establishing and interrupting an electric power cir-
`cuit.
`(PE) C57.l2.80—l978r
`contractual requirements Customer-imposed perfo1mance,lo—
`gistics, and other requirements and commitments governing
`the scope of software development, delivery, or support.
`(C/SE)
`1074-1995
`contrast (1) (image processing and pattern recognition) The
`difference between the average brightness of two subsets of
`an image.
`(C) 6l0.4—199O
`(2) (computer graphics) The relationship between the high-
`cst and lowest intensity levels of El display image, usually
`expressed as the ratio of light to dark.
`(C) 6l0.6—199l
`(3) (display presentation) The subjective assessment of the
`difference in appearance of two parts of a field of view seen
`simultaneously or successively. (Hence: luminosity contrast,
`lightness contrast, color contrast, simultaneous contrast, suc-
`cessive contrast). See also: photometry; television.
`[34]. [84]
`(BT)
`(4) (electric power systems in coimnercial buildings) In-
`dicates the degree of difference in light reflectance of the
`details of a task compared with its background.
`(IA) 241-1990
`contrast control A control, associated with a picture—disp1ay
`device, for adjusting the contrast ratio of the reproduced pic-
`
`control accuracy
`
`ture. Note: The contrast control is normally an amplitude con. ‘
`trol for the picture signal. In a monochrome-television sy.
`tem, both average luminance and the contrast
`ratio are
`affected. In a color—television system, saturation and hue also
`may be affected. See also: television,
`(EEC/PE)
`[119]
`contrast ratio (1) (television) The ratio of the maximum to the
`minimum luminance values in a television picture or a portion
`thereof. Note: Generally, the entire area of the picture is im-
`plied, but smaller‘ areas may be specified as in detail contrast.
`,
`(BT) 201-l979w
`(2) (amplitude, frequency, and pulse modulation) For any
`diffraction order,
`the ratio of the maximum light intensity
`to the minimum light
`intensity in the order,
`so that
`C = l,,,,,,(/1,,,,,,, where C is the contrast ratio. Note: In the
`limiting case when the depth of modulation is equal to 1, the
`minimum light intensity is due to background light, so that
`C = [max/lb. In the other extreme, when m = 0, the contrast
`ratio is equal to l.
`(UFFC)
`[17]
`(3) (acoustically tunable optical filter) The ratio of the dy-
`namic transmission at a given acoustic frequency and power
`level to the dynamic transmission with no applied acoustic
`power. Note: The contrast ratio is a measure of light leakage
`through the device. It should be specified for either a mono-
`chromatic or white light source input, and the angular spread
`of the input light.
`(UFFC)
`[17]
`contrast rendition factor (illuminating engineering) The ratio
`of visual task contrast with a given lighting environment to
`the contrast with sphere illumination.
`(EEC/IE)
`[126]
`contrast sensitivity (illuminatin