1、Designation: B 868 96 (Reapproved 2008)Standard Practice forContact Performance Classification of Electrical ConnectionSystems1This standard is issued under the fixed designation B 868; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice provides a uniform method of specifyingperformance requirements for (or reporting test r
3、esults of)electrical contact and connection systems. Both conductor andconnector system performance may be specified by this prac-tice, separately or in combination.1.2 This practice may be used for separable or permanentcontacts employing metallic conductors and contacts.1.3 This practice provides
4、methods for both signal andpower applications.1.4 This practice does not specify the sample preparation ortest sequences required for determining contact performance. Itis the responsibility of the user of this practice to determine theapplied test sequence(s) appropriate for the application.1.5 Thi
5、s standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to become familiarwith all hazards including those identified in the appropriateMaterial Safety Data Sheet (MSDS) for this product/materialas provid
6、ed by the manufacturer, to establish appropriatesafety and health practices, and determine the applicability ofregulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 539 Test Methods for Measuring Resistance of ElectricalConnections (Static Contacts)B 542 Terminology Relati
7、ng to Electrical Contacts andTheir UseB 812 Test Method for Resistance to Environmental Deg-radation of Electrical Pressure Connections InvolvingAluminum and Intended for Residential Applications2.2 UL Standard:UL 486B Wire Connectors for Use with Aluminum Con-ductors, Third Edition, 199133. Termino
8、logy3.1 Terms used in this practice are defined in TerminologyB 542 except as noted in 3.2.3.2 Definitions of Terms Specific to This Standard:3.2.1 conductor, nelectrically conductive member carry-ing current to a contact interface. Examples are wire and cable,busbar, and conductive paths on an etch
9、ed printed circuitboard.3.2.2 contact performance, ncontact interface behavior asindicated by initial electrical resistance and resistance changeunder the applied test conditions.4. Summary of Practice4.1 The prescribed performance specification (or reporting)statement consists of three sections, as
10、 follows:4.1.1 Performance Classification, in accordance with thispractice (Section 6).4.1.2 Variability Index, determined by sample size anddistribution of resistance values measured at end of test, inaccordance with this practice (Section 7).4.1.3 Statement of test method employed to determineperf
11、ormance classification.4.2 The format for the performance specification (or report-ing) statement is as follows:1This practice is under the jurisdiction of ASTM Committee B02 on NonferrousMetals and Alloys and is the direct responsibility of Subcommittee B02.11 onElectrical Contact Test Methods.Curr
12、ent edition approved March 1, 2008. Published March 2008. Originallyapproved in 1996. Last previous edition approved in 2002 as B 868 96 (2002)e3.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards
13、 volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Underwriters Laboratories (UL), 333 Pfingsten Rd., North-brook, IL 60062-2096, http:/.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United State
14、s.5. Significance and Use5.1 This practice is based on the use of electrical resistanceas an indicator of contact performance.5.2 Existing standards, such as those referenced in Section 2as representative examples, provide the basis for applied testconditions. Modifications in procedure or sample si
15、ze, or both,of existing standards may have to be made to provide forresistance measurement and to meet variability index require-ments that a user may specify.5.3 This practice accommodates the use of multiple testmethods, as may be required to assure satisfactory performancein a given application.6
16、. Performance Classification6.1 The performance classification statement consists ofthree letters in sequence indicating, respectively, category ofcontact (signal or power), average initial contact resistance,and change of average contact resistance as a consequence ofthe applied test conditions.6.2
17、 For this standard classification method, the performanceof a connection system for power applications is expressed asthe ratio of the contact resistance to the equivalent resistance ofthe attached conductor. The equivalent resistance of the con-ductor is the resistance of a length of solid circular
18、 conductorexactly one diameter in length. The conductor size used for theevaluation shall be that which is normally specified or utilizedwith the particular connection system being evaluated.6.2.1 For connection systems involving solid circular con-ductors, the equivalent resistance Rdis calculated
19、according tothe formula:Rd5 R 3 Dwhere:Rd= equivalent resistance,R = resistance per unit length, V, andD = diameter of conductor (in same length unit).6.2.1.1 Appendix X1 provides representative nominal datafor some common sizes of copper and aluminum conductors ofcircular cross section for the purp
20、ose of establishing instru-mentation requirements.6.2.2 For conductors with other than solid circular crosssection, equivalent diameter based on actual conductive cross-section area shall be used. For example: a conductor ofrectangular cross section 0.5 by 6 mm has a cross-section areaequal to that
21、of a solid circular conductor 1.95 mm in diameter,and therefore D in the equation in 6.2.1 is 1.95 mm.6.2.3 For contacts incorporating or connecting conductorsof different materials or cross section, or both, the Rdvalueused for contact performance determination shall be based onthe conductor of min
22、imum resistance per unit length.6.2.4 For contacts involving a connector, the conductormaterial and cross section used for determination of the Rdvalue to be used shall be the wire, busbar, circuit boardconductive strip, or other, as appropriate for the rating orrepresentative application of the con
23、nector. The conductor sizemay be determined according to the connector manufacturersspecification, current rating, or conventional application prac-tice.6.2.5 Conductor resistance per unit length is preferablydetermined by measurements incorporating the same instru-mentation used for contact resista
24、nce measurements, at thesame ambient temperature and current as for the contactperformance test being applied.6.2.6 When conductor resistance is determined at the sametime as contact performance in accordance with 6.2.5, and theconductor is solid with circular cross section, potential dropmeasuremen
25、ts may be used without conversion for the purposeof determining contact performance. (See example, AppendixX2.)6.3 Contact resistance shall be measured in accordance withTest Methods B 539.6.3.1 For power connections, resolution of resistance deter-mination shall be 0.1 Rdor better. For most applica
26、tions, thisrequires potential drop resolution of 10 V at a measurementcurrent density approximately equal to conductor ratings. (SeeAppendix X1.) Use Test Method B of Test Methods B 539adjusting the current to meet the stated current requirements.6.3.2 For signal connections, resolution of resistanc
27、e deter-mination shall be at 10 % of the average initial contactresistance or better, using Test Method C of Test MethodsB 539.6.3.3 For contact configurations in which bulk conductor orconnector resistance is included in the measured contactresistance, a single value of measured bulk resistance (se
28、e TestMethods B 539) shall be subtracted from the measured contactresistance values. Resolution of the bulk resistance measure-ment shall be 0.1 Rdor finer, and the bulk resistance measure-ment error tolerance shall be no greater than 60.2 Rd.6.4 The first letter of the performance classification, i
29、ndi-cating contact category, shall be “P” for power contacts andconnections and “S” for signal contacts and connections. Theletter is assigned according to the intended application for eachof the applied test conditions.6.4.1 A given connector type may be intended for multipleapplications, both sign
30、al and power (example: circuit boardconnector). The category used for performance classificationfor each test sequence applied shall be that for which the testsequence is intended.6.5 The letter indicating performance with respect to aver-age (arithmetic mean) initial resistance of all samples teste
31、dshall be in accordance with Table 1.6.6 The letter indicating performance with respect to resis-tance change of the worst-case sample tested shall be inaccordance with Table 2.B 868 96 (2008)27. Variability Index7.1 Variability Index for Power Category (P):7.1.1 The variability index V for power ca
32、tegory connec-tions is calculated from the resistance values determined at theend of the test sequence, expressed to two significant figures orto a resolution of 0.1 Rd.7.1.2 For power category connections, the variability indexis calculated by the following formula (see Note 1):V 5(i 5 1nRf/ Rd2 Rf
33、/ Rd!2n 2 1(1)where:Rf= final resistance for each connection tested, andRf= arithmetic mean final resistance for the total set of nconnections tested.NOTE 1While the variability index is numerically the same as thestatistical sample standard deviation, it should not be used for statisticalprediction
34、s of contact performance.7.2 Variability Index for Signal Category (S):7.2.1 The variability index V for signal category connec-tions is calculated from the resistance change from beginningto end of the test sequence, expressed to two significant figuresor to a resolution of 0.1 mV.7.2.2 For signal
35、category connections, the variability indexis calculated by the following formula (see Note 1):V 5(i 5 1nRc2 Rc!2n 2 1(2)where:Rc= resistance change for each connection tested, mV,andRc= arithmetic mean resistance change for the total set ofn connections tested, mV.8. Format8.1 A format for specifyi
36、ng connection or contact perfor-mance is: “Connections shall meet or exceed ASTM B 868Class XXX with YY variability index when tested according tothe applied conditions of ZZZ,” where “XXX” is the perfor-mance classification (Section 6),“YY” is the variability index(Section 7.1.1), and “ZZZ” is the
37、specified test method. Acondensed form is: “Connections shall meet or exceed ASTMB 868 Class XXX/YY/ZZZ.”8.2 A format for reporting contact performance test resultsis: “Performance is ASTM B 868 XXX with YY variabilityindex when tested according to the applied conditions of ZZZ.”A condensed form of
38、the statement is: “Tested contact perfor-mance is ASTM B 868 Class XXX/YY/ZZZ.”8.3 Parentheses may be used to indicate specific appliedconditions, sample size, conductors used, duration of test,portion of procedure applicable, or other necessary informa-tion.8.4 When a connections system is rated fo
39、r application tomultiple types or combinations of conductors, but is specifiedby a single classification, the worst-case performance classifi-cation shall be used. Multiple classifications may be utilized,provided that the conductor combinations for which the clas-sifications apply are adequately de
40、scribed. (Examples areprovided in Appendix X2.)8.5 The value of Rdused shall be reported for other thansolid circular conductors.8.6 According to the requirements of the application, morethan one test procedure can be specified.8.7 Example of use, including multiple test procedures andadditional par
41、enthetical information is: “Connections shallmeet or exceed ASTM B 868 Class PAB/1.0/ASTMB 812 90 (20 weeks, with any number of conductors, con-ductor material combinations, conductor size combinations forwhich the connector is rated to be used); ASTM B 868 ClassPAB/0.4/UL 486B (Section 6.11 of UL 4
42、86B, with any numberof conductors, conductor material combinations, or conductorsize combinations for which the connector is rated to be used).8.8 A detailed test record, including description of appliedconditions, test data, and the calculations for equivalent diam-eter, if other than solid circula
43、r conductor and Rd, shall beavailable.8.9 Examples of application of the performance classifica-tion method to several connection systems are provided inAppendix X2. (Note: the examples provided inAppendix X2 toillustrate application of the classification method are not to beinterpreted as specifica
44、tions of test requirements.)9. Precision and Bias9.1 Precision and bias are those of the test method(s)applied.10. Keywords10.1 classification; conductor; connector; contact; electricalcontact; electrical connection systems; metallic; resistanceTABLE 1 Initial Resistance IndicatorInitial ResistanceI
45、ndicatorAverage Initial ResistancePower Category (P) Signal Category (S)A Rc1.1 RdRc5 mVB2Rd10 mVC5Rd20 mVD 10 Rd50 mVE 100 Rd100 mVF 1000 Rd200 mVG $1000 Rd $200 mV corrected editorially.TABLE 2 Resistance Change IndicatorChange IndicatorPower Category (P) Signal Category (S)Ratio: Final/InitialRes
46、istanceof Worst-Case SampleResistance Change of Worst-Case Sample (Initialto Final Rc), mVA 1.1 0.5B 2 1.0C 5 2.0D 10 5.0E 100 10F 1000 20G $1000 $20 corrected editorially.B 868 96 (2008)3APPENDIXES(Nonmandatory Information)X1. EXAMPLES OF RESISTANCE AND POTENTIAL DROP PER RdX1.1 Table X1.1 and Tabl
47、e X1.2 of Appendix X1 areprovided for illustration purposes only and should not beinterpreted as specifications for test conditions or ratings.X1.2 Sample Calculation: for #1 AWG copper wire, 0.126ohm/1000 ft, 0.289-in. diameter.Rd= R 3 D (in same length units)= 0.126 3 0.289 3 1/(12 3 1000) = 3.03
48、VPotential drop per Rdat 110-A current = I 3 Rd=1103 3.03 = 333 VTABLE X1.1 Copper Conductors, Common SizesAm. WireGageDiameterDiameter,in.Cross Sec. Area,sq in.Copper,ohms per 1000 ftRd,micro-ohmMeasurement Current,ampsMicro-volts per RdatMeasurement Current000 0.41 0.132 0.063 2.15 165 35500 0.365
49、 0.105 0.0795 2.42 145 3510 0.325 0.0829 0.1 2.71 125 3391 0.289 0.0657 0.126 3.03 110 3332 0.258 0.0521 0.159 3.42 95 3253 0.229 0.0413 0.201 3.84 85 3264 0.204 0.0328 0.253 4.30 70 3016 0.162 0.0206 0.403 5.44 55 2998 0.128 0.013 0.641 6.84 40 27410 0.102 0.00815 1.02 8.67 30 26012 0.081 0.00513 1.62 10.94 25 27414 0.064 0.00323 2.58 13.76 20 27516 0.051 0.00203 4.09 17.38 15 26118 0.04 0.00128 6.51 21.70 11 23920 0.032 0.000802 10.4 27.73 9 25022 0.0253 0.000505 16.5 34.79 7 24324 0.0201 0.000317 26.2 43.89 6 26326 0.0159 0.0002 41.6 55.12 5 2
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