1、Designation: B868 96 (Reapproved 2013)Standard Practice forContact Performance Classification of Electrical ConnectionSystems1This standard is issued under the fixed designation B868; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 resu
3、lts of)electrical contact and connection systems. Both conductor andconnector system performance may be specified by thispractice, 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 metho
4、ds 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 This sta
5、ndard 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 provided by
6、 the manufacturer, to establish appropriatesafety and health practices, and determine the applicability ofregulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B539 Test Methods for Measuring Resistance of ElectricalConnections (Static Contacts)B542 Terminology Relating to E
7、lectrical Contacts and TheirUseB812 Test Method for Resistance to Environmental Degra-dation of Electrical Pressure Connections Involving Alu-minum and Intended for Residential Applications2.2 UL Standard:UL 486B Wire Connectors for Use with AluminumConductors, Third Edition, 199133. Terminology3.1
8、Terms used in this practice are defined in TerminologyB542 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 etched printe
9、d 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 follows:
10、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 determineperformance c
11、lassification.4.2 The format for the performance specification (or report-ing) statement is as follows:1This practice is under the jurisdiction ofASTM Committee B02 on NonferrousMetals and Alloys and is the direct responsibility of Subcommittee B02.11 onElectrical Contact Test Methods.Current editio
12、n approved Oct. 1, 2013. Published October 2013. Originallyapproved in 1996. Last previous edition approved in 2008 as B868 96 (2008).DOI: 10.1520/B0868-96R13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of
13、ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Underwriters Laboratories (UL), 333 Pfingsten Rd.,Northbrook, IL 60062-2096, http:/.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Un
14、ited StatesNOTICE: This standard has either been superseded and replaced by a new version or withdrawn.Contact ASTM International (www.astm.org) for the latest information15. Significance and Use5.1 This practice is based on the use of electrical resistanceas an indicator of contact performance.5.2
15、Existing standards, such as those referenced in Section 2as representative examples, provide the basis for applied testconditions. Modifications in procedure or sample size, or both,of existing standards may have to be made to provide forresistance measurement and to meet variability index require-m
16、ents 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. Performance Classification6.1 The performance classification statement consists ofthree letters in sequence indicating, respecti
17、vely, category ofcontact (signal or power), average initial contact resistance,and change of average contact resistance as a consequence ofthe applied test conditions.6.2 For this standard classification method, the performanceof a connection system for power applications is expressed asthe ratio of
18、 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 conductorexactly one diameter in length. The conductor size used for theevaluation shall be that which is normally specified or u
19、tilizedwith the particular connection system being evaluated.6.2.1 For connection systems involving solid circularconductors, the equivalent resistance Rdis calculated accord-ing to the formula:Rd5 R 3 Dwhere:Rd= equivalent resistance,R = resistance per unit length, , andD = diameter of conductor (i
20、n 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 purpose of establishing instru-mentation requirements.6.2.2 For conductors with other than solid circular crosssection, equivalent diam
21、eter 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 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 incorporat
22、ing or connecting conductorsof different materials or cross section, or both, the Rdvalueused for contact performance determination shall be based onthe conductor of minimum resistance per unit length.6.2.4 For contacts involving a connector, the conductormaterial and cross section used for determin
23、ation 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 connector. The conductor sizemay be determined according to the connector manufacturersspecification, current rating, or conventional
24、application prac-tice.6.2.5 Conductor resistance per unit length is preferablydetermined by measurements incorporating the same instru-mentation used for contact resistance measurements, at thesame ambient temperature and current as for the contactperformance test being applied.6.2.6 When conductor
25、resistance is determined at the sametime as contact performance in accordance with 6.2.5, and theconductor is solid with circular cross section, potential dropmeasurements may be used without conversion for the purposeof determining contact performance. (See example, AppendixX2.)6.3 Contact resistan
26、ce shall be measured in accordance withTest Methods B539.6.3.1 For power connections, resolution of resistance deter-mination shall be 0.1 Rdor better. For most applications, thisrequires potential drop resolution of 10 V at a measurementcurrent density approximately equal to conductor ratings. (See
27、Appendix X1.) Use Test Method B of Test Methods B539adjusting the current to meet the stated current requirements.6.3.2 For signal connections, resolution of resistance deter-mination shall be at 10 % of the average initial contactresistance or better, using Test Method C of Test MethodsB539.6.3.3 F
28、or contact configurations in which bulk conductor orconnector resistance is included in the measured contactresistance, a single value of measured bulk resistance (see TestMethods B539) shall be subtracted from the measured contactresistance values. Resolution of the bulk resistance measure-ment sha
29、ll 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, indi-cating contact category, shall be “P” for power contacts andconnections and “S” for signal contacts and connections. Theletter is a
30、ssigned according to the intended application for eachof the applied test conditions.6.4.1 A given connector type may be intended for multipleapplications, both signal and power (example: circuit boardconnector). The category used for performance classificationfor each test sequence applied shall be
31、 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 testedshall be in accordance with Table 1.B868 96 (2013)26.6 The letter indicating performance with respect to resis-tance change of the wor
32、st-case sample tested shall be inaccordance with Table 2.7. Variability Index7.1 Variability Index for Power Category (P):7.1.1 The variability index V for power category connec-tions is calculated from the resistance values determined at theend of the test sequence, expressed to two significant fig
33、ures 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!(i51nRf/Rd2 Rf/Rd!2n 2 1(1)where:Rf= final resistance for each connection tested, andRf= arithmetic mean final resistance for the total set of nconnecti
34、ons tested.NOTE 1While the variability index is numerically the same as thestatistical sample standard deviation, it should not be used for statisticalpredictions of contact performance.7.2 Variability Index for Signal Category (S):7.2.1 The variability index V for signal category connec-tions is ca
35、lculated from the resistance change from beginningto end of the test sequence, expressed to two significant figuresor to a resolution of 0.1 m.7.2.2 For signal category connections, the variability indexis calculated by the following formula (see Note 1):V 5!(i51nRc2 Rc!2n 2 1(2)where:Rc= resistance
36、 change for each connection tested, m, andRc= arithmetic mean resistance change for the total set of nconnections tested, m.8. Format8.1 A format for specifying connection or contact perfor-mance is: “Connections shall meet or exceed ASTM B868Class XXX withYYvariability index when tested according t
37、othe 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 specified test method. Acondensed form is: “Connections shall meet or exceed ASTMB868 Class XXX/YY/ZZZ.”8.2 A format for reporting contact perfor
38、mance test resultsis: “Performance is ASTM B868 XXX with YY variabilityindex when tested according to the applied conditions of ZZZ.”A condensed form of the statement is: “Tested contact perfor-mance is ASTM B868 Class XXX/YY/ZZZ.”8.3 Parentheses may be used to indicate specific appliedconditions, s
39、ample size, conductors used, duration of test,portion of procedure applicable, or other necessary informa-tion.8.4 When a connections system is rated for application tomultiple types or combinations of conductors, but is specifiedby a single classification, the worst-case performance classifi-cation
40、 shall be used. Multiple classifications may be utilized,provided that the conductor combinations for which the clas-sifications apply are adequately described. (Examples areprovided in Appendix X2.)8.5 The value of Rdused shall be reported for other thansolid circular conductors.8.6 According to th
41、e requirements of the application, morethan one test procedure can be specified.8.7 Example of use, including multiple test procedures andadditional parenthetical information is: “Connections shallmeet or exceed ASTM B868 Class PAB/1.0/ASTM B812 90(20 weeks, with any number of conductors, conductor
42、materialcombinations, conductor size combinations for which theconnector is rated to be used); ASTM B868 Class PAB/0.4/UL486B (Section 6.11 of UL486B, with any number ofconductors, conductor material combinations, or conductorsize combinations for which the connector is rated to be used).8.8 A detai
43、led test record, including description of appliedconditions, test data, and the calculations for equivalentdiameter, if other than solid circular conductor and Rd, shall beavailable.8.9 Examples of application of the performance classifica-tion method to several connection systems are provided inApp
44、endix X2. (Note: the examples provided in Appendix X2to illustrate application of the classification method are not tobe interpreted as specifications of test requirements.)9. Precision and Bias9.1 Precision and bias are those of the test method(s)applied.TABLE 1 Initial Resistance IndicatorInitial
45、ResistanceIndicatorAverage Initial ResistancePower Category (P) Signal Category (S)A Rc1.1 RdRc5 mB2Rd10 mC5Rd20 mD 10 Rd50 mE 100 Rd100 mF 1000 Rd200 mG $1000 Rd $200 m corrected editorially.TABLE 2 Resistance Change IndicatorChange IndicatorPower Category (P) Signal Category (S)Ratio: Final/Initia
46、lResistanceof Worst-Case SampleResistance Change of Worst-Case Sample (Initialto Final Rc), mA 1.1 0.5B 2 1.0C 5 2.0D 10 5.0E 100 10F 1000 20G $1000 $20 corrected editorially.B868 96 (2013)310. Keywords10.1 classification; conductor; connector; contact; electricalcontact; electrical connection syste
47、ms; metallic; resistanceAPPENDIXES(Nonmandatory Information)X1. EXAMPLES OF RESISTANCE AND POTENTIAL DROP PER RdX1.1 Table X1.1 and Table X1.2 of Appendix X1 areprovided for illustration purposes only and should not beinterpreted as specifications for test conditions or ratings.X1.4 Sample Calculati
48、on: for #1 AWG copper wire, 0.126ohm/1000 ft, 0.289-in. diameter.Rd= R D (in same length units)= 0.126 0.289 1(12 1000) = 3.03 Potential drop per Rdat 110-A current = I Rd= 110 3.03 = 333 VTABLE X1.1 Copper Conductors, Common SizesAm. WireGageDiameterDiameter,in.Cross Sec. Area,sq in.Copper,ohms per
49、 1000 ftRd,micro-ohmMeasurement Current,ampsMicro-volts per RdatMeasurement Current000 0.41 0.132 0.063 2.15 165 35500 0.365 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 0.00
