1、Designation: D 2864 07Standard Terminology Relating toElectrical Insulating Liquids and Gases1This standard is issued under the fixed designation D 2864; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe definitions contained in this terminology pertain to terms as they are used in conjunction withfluid insulating materials. Insofar
3、 as possible, the definitions are consistent with accepted generalusage, and may also contain additional information deemed to be of value in testing of fluid insulatingmaterials.1. Referenced Documents1.1 ASTM Standards:2D611 Test Methods for Aniline Point and Mixed AnilinePoint of Petroleum Produc
4、ts and Hydrocarbon SolventsD 2007 Test Method for Characteristic Groups in RubberExtender and Processing Oils and Other Petroleum-Derived Oils by the Clay-Gel Absorption Chromato-graphic MethodD 2140 Test Method for Carbon-Type Composition of In-sulating Oils of Petroleum OriginD 2300 Test Method fo
5、r Gassing of Electrical InsulatingLiquids Under Electrical Stress and Ionization (ModifiedPirelli Method)D 2500 Test Method for Cloud Point of Petroleum ProductsD3117 Test Method for WaxAppearance Point of DistillateFuelsE 355 Practice for Gas Chromatography Terms and Rela-tionships2. Terminologyacs
6、ymbol used to designate an electric voltage or currentwhose amplitude varies periodically as a function of time, itsaverage value over one complete period being zero. Onecomplete repetition of the wave pattern is referred to as aCYCLE, and the number of cycles occurring in one secondis called the FR
7、EQUENCY, measured in hertz (Hz). Forexample, the electricity supplied by commercial utilitycompanies in the United States is, in most localities, 60 Hz,although other frequencies may be encountered.acid treatinga refining process in which an unfinishedpetroleum insulating oil is contacted with sulfu
8、ric acid toimprove its color, odor, stability, and other properties.ac loss characteristicsthose properties of a dielectric orinsulation system (such as dissipation factor, power factor,and loss index) that may be used as a measure of the poweror energy losses that would result from the use of suchm
9、aterial in an ac electric field.additivea chemical compound or compounds added to aninsulating fluid for the purpose of imparting new propertiesor altering those properties which the fluid already has.ambient temperaturethe temperature of the surroundingatmosphere as determined by an instrument shie
10、lded fromdirect or reflected rays of the sun.aniline pointthe minimum temperature for complete misci-bility of equal volumes of aniline and the sample under test.See Test Methods D611. In comparing two samples ofsimilar molecular weight, the aniline point can be used as ameans of comparing aromatic
11、content of the two samples. Aproduct of high aniline point will be low in aromatics andnaphthenes, and therefore high in paraffins.API gravityan arbitrary scale developed by the AmericanPetroleum Institute and frequently used in reference topetroleum insulating oil. The relationship between APIgravi
12、ty and specific gravity 60/60F is defined by thefollowing:Deg API Gravity at 60F 5 141.5/sp gr 60/60F!2131.51This terminology is under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gases and is the direct responsibility of Subcom-mittee D27.15 on Planning Resource and De
13、velopment.Current edition approved July 1, 2007. Published August 2007. Originallyapproved in 1970. Last previous edition approved in 2006 as D 2864 06.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMSta
14、ndards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.aromaticsthat class of organic compounds which behavechemically like benzene. They are cyclic
15、unsaturated organiccompounds that can sustain an induced electronic ringcurrent due to delocalization of electrons around the ring.DISCUSSIONEmpirically, the aromatic portion of a mineral insulat-ing oil can be estimated by correlation with physical properties (SeeTest Method D 2140), or by selectiv
16、e adsorption on clay-gel (See TestMethod D 2007).askarela generic term for a group of synthetic, fire-resistant,chlorinated aromatic hydrocarbons used as electrical insu-lating liquids. They have a property under arcing conditionssuch that any gases produced will consist predominantly ofnoncombustib
17、le hydrogen chloride with lesser amounts ofcombustible gases.atomic absorptionthe absorption of radiant energy byground state atoms. Substances when dispersed as an atomicvapor will absorb characteristic radiations identical to thosewhich the same substances can emit. This property is thebasis for a
18、nalysis by atomic absorption spectroscopy.capacitivitythe same as permittivity, relative.colora quality of visible phenomena of insulating fluids, thenumerical value for which is derived by comparing thisquality using transmitted light with that of a series ofnumbered reference bustible gasesflammab
19、le gases formed from breakdown(partial or complete) of some insulating materials subjectedto electrical or thermal stress, or both.conductancethe ratio of the current carried through amaterial to the difference in potential applied across thematerial. It is the reciprocal of resistance. The unit is:
20、ohm)1or siemens.DISCUSSION1Conductance is a general term. Specific referencemay be made to conductance dc and conductance ac.DISCUSSION2For dielectrics the conductance may be dependenton the electrification time.conductance, apparent dcthe dc conductance measured atthe end of a specific electrifica
21、tion time. The “apparent dcconductance” is the reciprocal of the “apparent dc resis-tance.” The unit is: (ohm)1or siemens.DISCUSSIONThe term “apparent dc conductance” is used to distin-guish the current-voltage relationship found in electrical insulatingmaterials, where the current (leakage plus abs
22、orption) usually decreaseswith time, from the relationship found in metallic conductors where thesteady-state current is reached in a fraction of a second.conductance, dcthe ratio of the total current (in amperes)passing through a material to the dc voltage (in volts) appliedbetween two electrodes t
23、hat are in contact with, or immersedin a specimen. The “dc conductance” is the reciprocal of the“dc resistance.” The unit is: (ohm)1or siemens.conductivitythe ratio of the current density carried througha specimen to the potential gradient paralleling the current.This is numerically equal to the con
24、ductance betweenopposite faces of a unit cube of liquid. It is the reciprocal ofresistivity.DISCUSSION1Conductivity is a general term. Specific referencemay be made to conductivity, dc.DISCUSSION2For dielectrics the conductivity may be dependenton the electrification time. (See also conductivity, ap
25、parent dcvolume and conductivity, dc volume.)conductivity, apparent dc volumethe “dc volume conduc-tivity” measured at the end of a specified electrification time.It is the reciprocal of the apparent dc volume resistivity. Theunit most commonly used is: (ohm-centimetre)1or siemensper centimetre. The
26、 SI unit is (ohm-metre)1.conductivity, dcthe ratio of the current density passingthrough a specimen at a given instant of time and underprescribed conditions, to the dc potential gradient parallelingthe current. It is the reciprocal of the dc resistivity. Incommon practice the “dc conductivity” is n
27、umerically equalto the “dc conductance” between opposite faces of a centi-metre cube of liquid. The unit is: (ohm-centimetre)1orsiemens per centimetre. The SI unit is: (ohm-metre)1.DISCUSSIONThe “dc conductivity” may contain components of bothsurface conductance and volume conductance, but, in gener
28、al, surfaceeffects are not common in measurements on fluid dielectrics. Theproperty most commonly measured is either the “dc volume conduc-tivity” or the “apparent dc volume conductivity.”conductivity, dc volumethe property of a material thatpermits the flow of electricity through its volume. It isn
29、umerically equal to the ratio of the steady-state currentdensity to the steady direct voltage gradient parallel with thecurrent in the material. The dc volume conductivity is thereciprocal of the dc volume resistivity. The unit commonlyused is: (ohm-centimetre)1or siemens per centimetre. TheSI unit
30、is (ohm-metre)1.DISCUSSIONFor electrical insulating materials the time required forthe steady-state current to be reached may be very long; from severalminutes to several months may be required.coronaa luminous discharge due to ionization of the airsurrounding an electrode, caused by the high electr
31、ic fieldstrength in the vicinity of the electrode, exceeding a certaincritical (that is, threshold) value.corona effectlight emitted in the UV range of the electro-magnetic spectrum by electronically excited molecules thathave reached a singlet state and have not consumed theabsorbed energy by other
32、 physical process.corona (partial discharge) inception voltage, CIVthe low-est voltage at which continuous partial discharge (or corona)exceeding a specified intensity is observed as the appliedvoltage is gradually increased. Where the applied voltage isalternating, the CIV is expressed as 1/=2 of t
33、he peakvoltage.corona (partial discharge) extinction voltage, CEVthehighest voltage at which partial discharge (or corona) nolonger exceeds a specified intensity as the applied voltage isgradually decreased from a value above the corona inceptionvoltage. Where the applied voltage is alternating the
34、CEV isexpressed as 1/=2 of the peak voltage.D 2864 072corrosive sulfurn, elemental sulfur and thermally unstablesulfur compounds in electrical insulating oil that can causecorrosion of certain transformer metals such as copper andsilver.dcsymbol used to designate an electric voltage or currentwhose
35、amplitude does not vary periodically with respect totime, as for example the output of a chemical cell or that ofa thermocouple. The term is also applied to the output ofsuch devices as dynamos and rectifiers, whose amplitude isnot strictly time-invariant.dew-point temperaturethe temperature (above
36、0C) towhich a gas or vapor must be cooled at constant pressure andconstant water-vapor composition in order for saturation tooccur.DISCUSSIONAt temperatures below 0C, vapor may first be noticedin the form of frost. It is common to refer to the temperature at whichthis occurs as the frost-point tempe
37、rature. Dew-point temperatures alsoexist for other gas or vapor systems in which saturation with respect toa substance other than water vapor can occur.dielectrica medium in which it is possible to maintain anelectric field with little supply of energy from outsidesources. The energy required to pro
38、duce the electric field isrecoverable, in whole or in part. A vacuum, as well as anyinsulating material is a dielectric.dielectric breakdown voltagethe potential difference atwhich electrical failure occurs in an electrical insulatingmaterial or insulation structure, under prescribed test condi-tion
39、s.dielectric constant See dielectric constant, relative (espe-cially Note 2). (See also permittivity (especially Note 2).)dielectric constant, absolutethe same as permittivity.dielectric constant, relativethe same as permittivity, rela-tive.DISCUSSION1Current practice including international usage i
40、s toprefer the term relative permittivity.DISCUSSION2Common usage has been to drop the term “relative”and simply use dielectric constant when the dimensionless ratio is thequantity being referred to.dielectric failurethe failure of an element in a dielectriccircuit that exists when the insulating el
41、ement becomesconducting. This event may take the form of a gradualincrease in current exceeding a specified value, but it usuallytakes the form of an almost instantaneous charge transferaccompanied by collapse of the insulating properties andpartial of complete localized destruction of the dielectri
42、cmedium. In the case of liquids and gases the failure may beself-healing.dielectric strengtha property of an insulating materialdescribed by the average voltage gradient at which electricbreakdown occurs under specific conditions of test.dissipation factor, Dthe ratio of the loss index to its relati
43、vepermittivity orD 5k9/k8It is also the tangent of its loss angle, d, or the cotangent ofits phase angle, u. The dissipation factor is related to the powerfactor, PF, by the following equation:D 5 PF/=1 2 PF !2DISCUSSIONIt may be expressed as D = tan d = cotan u =G/vCp5 1/vCpRp5vRsCswhere G is the e
44、quivalent parallel ac conductance, Cpis the parallelcapacitance, Rpis the equivalent parallel ac resistance, Csis the seriescapacitance, and Rsis the equivalent series resistance.dissipation factor, dielectricsame as dissipation factor.electric constant the same as permittivity of free space.electri
45、c creepage strengththe average voltage gradientunder specific conditions of test and for a specific electrodeconfiguration, at which dielectric failure occurs along theinterface between a solid insulating material and the fluid inwhich it is immersed, or at the interface between two solidsthat are i
46、n close physical contact with each other but are notbonded chemically. Dielectric creepage failure may result intracking.electrical dischargea discontinuous movement of electricalcharges through an insulating medium, initiated by electronavalanches and supplemented by secondary processes.electrifica
47、tion timethe time during which a steady directpotential is applied to electrical insulating materials beforethe current is measured.emulsified waterwater that is suspended in insulating liquidas clusters of water molecules. It usually gives insulatingliquid a milky appearance.ester-based insulating
48、fluidan insulating fluid that may beeither synthetic or natural-based. Synthetic ester fluids areproduced by the reaction of an organic acid with an alcohol,usually a diol, triol, or tetraol. Natural ester fluids are derivedfrom an animal or agricultural (vegetable or seed) source.They are generical
49、ly referred to as triglycerides, being acombination of glycerol and various organic acids of varyingmolecular weights.fire pointthe lowest temperature at which a specimen willsustain burning for 5 s under specified conditions of test.flash pointthe lowest temperature corrected to a barometricpressure of 101.3 kPa (760 mm Hg), at which application ofa test flame causes the vapor of a specimen to ignite underspecified conditions of test.fluorescencephotoluminescence in which the emitted opticalr
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