1、Designation: B 868 96 (Reapproved 2002)e3Standard 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 revis
2、ion, 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.e1NOTEParagraph 1.5 was corrected editorially in June 2002.e2NOTEEditorial changes were made throughout in March
3、 2005.e3NOTEEditorial changes were made in Table 1, Table 2, 4.2, and X1.2 in March 2006.1. Scope1.1 This practice provides a uniform method of specifyingperformance requirements for (or reporting test results of)electrical contact and connection systems. Both conductor andconnector system performan
4、ce 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 methods for both signal andpower applications.1.4 This practice does not specify the sample prepa
5、ration 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 standard does not purport to address all of thesafety concerns, if any, associated with its use
6、. It is theresponsibility of the user of this standard to become familiarwith all hazards including those identified in the appropriateMaterial Safety Data Sheet for this product/material as pro-vided by the manufacturer, to establish appropriate safety andhealth practices, and determine the applica
7、bility of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 539 Test Methods for Measuring Resistance of ElectricalConnections (Static Contacts)B 542 Terminology Relating to Electrical Contacts andTheir UseB 812 Test Method for Resistance to Environmental Deg-radation o
8、f 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. Terminology3.1 Terms used in this practice are defined in TerminologyB 542 except as noted in 3.2.3.2 Definit
9、ions 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 printed circuitboard.3.2.2 contact performance, ncontact interface behavior asindicated by initial
10、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:4.1.1 Performance Classification, in accordance with thispractice (Section 6).4.1.2 Variabili
11、ty 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 classification.4.2 The format for the performance specification (or report-ing) statement is a
12、s 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.Current edition approved March 10, 1996. Published May 1996. Originallyapproved in 1996. Last previous edi
13、tion approved in 1996 as B 868 96.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Underwriter
14、s Laboratories (UL), Corporate Progress, 333Pfingsten Rd., Northbrook, IL 60062.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Significance and Use5.1 This practice is based on the use of electrical resistanceas an indicator of c
15、ontact 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 size, or both,of existing standards may have to be made to provide forresistance measurement and to meet vari
16、ability 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. Performance Classification6.1 The performance classification statement consists ofthree letters in sequen
17、ce 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 For this standard classification method, the performanceof a connection system for power applications is e
18、xpressed 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 conductorexactly one diameter in length. The conductor size used for theevaluation shall be that which is
19、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 according tothe formula:Rd5 R 3 Dwhere:Rd= equivalent resistance,R = resistance per unit length, V, andD =
20、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 purpose of establishing instru-mentation requirements.6.2.2 For conductors with other than solid circular cross
21、section, 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 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
22、 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 minimum resistance per unit length.6.2.4 For contacts involving a connector, the conductormaterial and cross s
23、ection 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 connector. The conductor sizemay be determined according to the connector manufacturersspecification, current
24、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 resistance measurements, at thesame ambient temperature and current as for the contactperformance test being appli
25、ed.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 dropmeasurements may be used without conversion for the purposeof determining contact performance. (See example, Appendix
26、X2.)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 applications, thisrequires potential drop resolution of 10 V at a measurementcurrent density approximately equal t
27、o 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 resistance deter-mination shall be at 10 % of the average initial contactresistance or better, using Test Method C o
28、f 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 (see TestMethods B 539) shall be subtracted from the measured contactresistance values. Resolution of the bulk
29、 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, indi-cating contact category, shall be “P” for power contacts andconnections and “S” for signal contacts and
30、 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 signal and power (example: circuit boardconnector). The category used for performance classificationfor each te
31、st 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 testedshall be in accordance with Table 1.6.6 The letter indicating performance with respect to resis-tance chan
32、ge of the worst-case sample tested shall be inaccordance with Table 2.B 868 96 (2002)e327. 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, e
33、xpressed 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/ Rd!2n 2 1(1)where:Rf= final resistance for each connection tested, andRf= arithmetic mean final resista
34、nce 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 statisticalpredictions of contact performance.7.2 Variability Index for Signal Category (S):7.2.1 The variability index V for
35、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 category connections, the variability indexis calculated by the following formula (see Note 1):V 5(i 5 1n
36、Rc2 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 specifying connection or contact perfor-mance is: “Connections shall meet or exceed ASTM B 868Class XXX with YY v
37、ariability 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 specified test method. Acondensed form is: “Connections shall meet or exceed ASTMB 868 Class XXX/YY/ZZZ.”
38、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 the statement is: “Tested contact perfor-mance is ASTM B 868 Class XXX/YY/ZZZ.”8.3 Parentheses may be use
39、d 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 for application tomultiple types or combinations of conductors, but is specifiedby a single classification,
40、 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 described. (Examples areprovided in Appendix X2.)8.5 The value of Rdused shall be reported for other thanso
41、lid 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 parenthetical information is: “Connections shallmeet or exceed ASTM B 868 Class PAB/1.0/ASTMB81290(20 weeks,
42、 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 486B, with any numberof conductors, conductor material combinations, or conductorsize combinations for which
43、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 circular conductor and Rd, shall beavailable.8.9 Examples of application of the performance classifica-tion method
44、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 specifications of test requirements.)9. Precision and Bias9.1 Precision and bias are those of the test method(s)appli
45、ed.10. Keywords10.1 classification; conductor; connector; contact; electricalcontact; electrical connection systems; metallic; resistanceTABLE 1 Initial Resistance IndicatorInitial ResistanceIndicatorAverage Initial ResistancePower Category (P) Signal Category (S)A Rc1.1RdRc5mVB2Rd10 mVC5Rd20 mVD 10
46、 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/InitialResistanceof Worst-Case SampleResistance Change of Worst-Case Sample (Initialto Final Rc), mVA 1.1 0.5B 2 1.0C 5
47、2.0D 10 5.0E 100 10F 1000 20G $1000 $20 corrected editorially.B 868 96 (2002)e33APPENDIXES(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 specificati
48、ons 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 VPotential drop per Rdat 110-A current = I 3 Rd=1103 3.03 = 333 VTABLE X1.1 Copper Conductors, Common SizesA
49、m. 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 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 4.0
