1、Designation: B 854 98 (Reapproved 2004)Standard Guide forMeasuring Electrical Contact Intermittences1This standard is issued under the fixed designation B 854; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisi
2、on. 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 The techniques described in this guide apply to electri-cal circuits that include one or more electrical contacts indevices such
3、 as slip rings, separable connectors, electrome-chanical relays or closed switch contacts. The user shoulddetermine applicability for other devicesTable 1.1.2 The range of techniques described apply to circuitdiscontinuities (intermittences) of durations ranging from ap-proximately 10 nanoseconds to
4、 several seconds and of suffi-cient magnitude to cause alteration of the circuit function.Extension of the guide to shorter duration events may bepossible with suitable instrumentation. Events of longer dura-tion may be monitored by techniques for dc measurementssuch as those described in Test Metho
5、ds B 539 or by adaptationof methods described in this guide.1.3 The techniques described in this guide apply to electri-cal circuits carrying currents typical of signal circuits. Suchcurrents are generally less than 100 ma. Extension of thesetechniques to circuits carrying larger currents may be pos
6、sible,but the user should evaluate applicability first.1.4 This 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 appropriateMateri
7、al Safety Data Sheet for this product/material as pro-vided by the manufacturer, to establish appropriate safety andhealth practices, and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 539 Test Methods for Measuring Resistance of Electr
8、icalConnections (Static Contacts)B 542 Terminology Relating to Electrical Contacts andTheir UseB 615 Practice for Measuring Electrical Contact Noise inSliding Electrical ContactsB 878 Test Method for Nanosecond Event Detection forElectrical Contacts and Connectors2.2 Other Documents:IEC Publication
9、512, Test 2e Contact Disturbance3EIA-364-46 Continuity Test Procedure for ElectricalConnectors43. Terminology3.1 Terms relevant to this guide are defined in TerminologyB 542 except as noted in the following section.3.2 Definitions of Terms Specific to This Standard:3.2.1 intermittencea transient inc
10、rease in the voltagedrop across a pair of electrical contacts.4. Significance and Use4.1 This guide suggests techniques to evaluate intermit-tences in a contact pair while it is subjected to simulated oractual environmental stress. Such measurements are a valuabletool in predicting circuit performan
11、ce under these stressconditions and in diagnosing observed problems in circuitfunction under such conditions.4.2 This document is intended to provide some generalguidance on the best available practices for detecting, quanti-fying, characterizing and reporting short duration intermit-tences in circu
12、its containing electrical contacts. Certain envi-ronmental stresses such as mechanical shock, vibration ortemperature change may cause intermittences. These measure-ment procedures include methods applicable to contacts oper-ating under various conditions in testing or in service.4.3 Practice B 615
13、defines methods for measuring electricalcontact noise in sliding electrical contacts. In contrast GuideB 854 provides guidance to the various methods for measuringsimilar phenomena in static contacts.5. Apparatus5.1 General CommentsThe apparatus required varies de-pending upon the technique selected
14、 and the parameters (suchas duration and magnitude) of the intermittence that the user1This guide 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 May 1, 2
15、004. Published May 2004. Originallyapproved in 1998. Last previous edition approved in 1998 as B 854 98.2For 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 standard
16、s Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.4Available from Electronic Industries Association, 2001 Pennsylvania Ave NW,Washington D.C. 20006.1Copyright ASTM International, 100 Barr Harbor Drive
17、, PO Box C700, West Conshohocken, PA 19428-2959, United States.wants to detect. In general, the cabling must be capable ofcarrying signals of the speed to be detected in the study, andmust be isolated from sources of noise that may cause falseindications.5.2 Special Precautions for Measurements Invo
18、lving EventsLess than 1 Microsecond in DurationDetection of events ofduration less than 1 microsecond will require special attentionto the wiring of the detection circuits and instrumentation.Such attention may include using coaxial cable, shielding theapparatus from interferences and minimizing cab
19、le lengths.5.3 Specific ApparatusThe apparatus required will varydepending upon the measurement method selected and theenvironmental stresses imposed during the test.6. Procedure6.1 General CommentsThe following sections describe,in general terms, several methods that have been used to detector meas
20、ure contact intermittences. The user should select anappropriate method and adapt it as required. Table 1 presents acomparison of the attributes of the various methods. Thefollowing list covers questions that the user should answerbefore selecting a test method.6.1.1 What is the definition of an int
21、ermittence in theintended application? For example, what resistance changeover what time interval constitutes an intermittence, or whaterror occurs if the contact resistance changes, or what otherdefinition is appropriate for the intended purpose of the testresults?6.1.2 Is it necessary to monitor m
22、ore than one contactsimultaneously? If so, is it acceptable to connect the contacts inseries? If contacts cannot be connected in series, how manycontacts must be measured simultaneously?6.2 Test results should be reported in a format appropriatefor the application and consistent with the format supp
23、lied bythe test instrument.6.3 OscilloscopeIn this method, an oscilloscope is wiredto monitor the potential across the contact(s) of interest whilea signal is passed through the contacts. Standards such as IECPublication 512, Test 2e or EIA 364-46 are often implementedusing this method. Practice B 6
24、15 provides a specific circuitthat uses this method. Examples of the use of this method areshown in the reference by Currence and Rhoades.56.3.1 Fig. 1 shows a schematic representation of anexample of how this method may be implemented. In selectingan oscilloscope, choose a model with response time
25、fastenough to observe events of the duration of interest in thestudy. The user may find it convenient to use an oscilloscopecapable of storing and printing results.6.4 Custom CircuitryIn this method, the user assemblescircuitry to measure the effects of the intermittences under theconditions of inte
26、rest. For example, the circuitry may simulatethe type of source and detector circuitry that the user plans todesign into a system. Alternatively, the user may designcircuitry based on specialized components to achieve capabili-ties different from those found in commercial instruments. Anexample of c
27、ustom circuitry was described by Abbott andSchreiber.66.4.1 Fig. 2 shows a schematic representation of an exampleof how this method may be implemented. The source anddetector incorporate the specific devices, technology, driver5Currence, R. and Rhoades, W., “Predicting, Modeling and Measuring Transi
28、entResistance Changes of Degraded Electrical Contacts,” Electrical Contacts, Proceed-ings of the 29th Meeting of the Holm Conference on Electrical Contacts, IllinoisInstitute of Technology, p. 81, 1983.6Abbott, W. H. and Schreiber, K. L., “Dynamic Contact Resistance of Gold, Tinand Palladium Connect
29、or Interfaces During Low Amplitude Motion,” Proceedingsof Holm Conference, 1981, p. 211.TABLE 1 Comparison of Methods of Monitoring Electrical Contact IntermittencesMethodTypical Numberof ChannelsTypical Event Characterization Possible AdvantagesOscilloscope 1, 2 or 4 DV vs time detailed characteriz
30、ation of each eventCustom Circuitry 1 per circuit Presence or absence of one or more events during apreselected monitoring interval, such events definedas above a preselected threshold of DR and duration,the number of events during the interval may or maynot be recorded.Ability to closely model actu
31、al circuit conditions,allows use of various technologies in the transmittingand receiving devicesEvent Detector 1 to 64 Presence or absence of one or more events during apreselected monitoring interval, such events definedas above a preselected threshold of DR and duration,but the number of events d
32、uring the interval is notrecorded.Multichannel capability, selection of thresholds forevents to be countedBit Error Rate 1 ratio of errors to number of bits transmitted The format of the results is readily applicable toranking of interconnection devices with respect totransmission quality for a spec
33、ific signal formatFIG. 1 Schematic Representation of Oscilloscope MethodB 854 98 (2004)2circuits, amplifiers, etc., that are of interest in the intendedapplication of the connection or switch under test. The controland monitoring instrumentation monitors the performance ofthe connecting circuit by a
34、 suitable method such as comparingthe signal received against a standard.6.5 Commercial Event DetectorIn this method, a com-mercial instrument that detects high resistance events is wiredto monitor one or more electrical contacts under evaluation.Test Method B 878 gives detailed instructions for imp
35、lement-ing a specific version of this method. Certain instruments allowmonitoring of several electrical contacts independently andsimultaneously. Typically, the instrument has a pair of termi-nals for each channel to be monitored: a transmit terminal anda receive terminal. Each contact to be evaluat
36、ed is wired into acable that runs from the transmit terminal, through the testcontact, to the receive terminal. Carefully follow all instruc-tions and recommendations of the instrument manufacturer inmaking these connections.6.5.1 The resistance change and the event duration requiredto trigger the e
37、vent detector should be set according to theinstructions of the instrument manufacturer. These levelsshould be selected based on the requirements of the system inwhich the contacts are intended to be used.6.5.2 It is good practice to conduct a control experimentusing similar wiring without the test
38、contact in the circuit. Inthe case where the monitoring instruments have multiplechannels available, wiring one or more of the channels as anexperimental control is recommended. This control channel(s)should be wired with cables that are of the same types andlengths as those used for the test channe
39、ls. The routing of thecable for the control channel(s) should follow the routing of thetest channels as nearly as feasible.6.5.3 If events are detected in a control channel, interferenceis suspected. Events in the control channel invalidate theassociated test.6.5.4 After the contact(s) under test ar
40、e wired to theinstrument, monitoring may begin. Typically, monitoring con-tinues for a fixed time and the number of events is recorded. Ifthe contacts are stressed, for example, through thermal cyclesor mechanical disturbance, it is appropriate to conduct acontrol experiment where the same contacts
41、are monitored forthe same length of time under the same measurement condi-tions but without the imposed external stress.76.5.5 Fig. 3 shows a schematic representation of an exampleof how this method may be implemented. In the instrumentillustrated, each channel has a “send” and “receive” terminal. A
42、connection or switch in the device under test is wired into acable connecting the send and receive terminals for eachchannel. The instrument itself monitors the performance ofeach channel and indicates interruptions on a suitable displayfor each channel.Fig. 36.5.6 As mentioned in 6.1, test results
43、should be reported ina format appropriate for the application and consistent with theformat supplied by the test instrument. Typically, an eventdetector records if one or more events occurred during a fixedperiod of time, but may not tell how many events occurred ortheir magnitudes above the preset
44、threshold. The report maylist the total number of measurement periods and the number ofperiods during which events occurred, and any correlationbetween applied environmental stresses and events.6.6 Bit Error Rate DetectorIn this method, a digital signalis passed through the interconnection device un
45、der evaluationand into a signal receiving device. The signal received iscompared with the signal transmitted, and the number of errorsdetected during a fixed time period is recorded. The ratio of thenumber of errors counted to the number of bits transmitted iscalculated and reported as the bit error
46、 rate. Alternatively, one7Examples of instruments of the type described are built by AnaTech Inc.,Wakefield, Massachusetts. Similar instruments may be available from other manu-facturers.FIG. 2 Schematic Representation of Method Using CustomCircuitryFIG. 3 Schematic Representation of Method Using Co
47、mmercialEvent Detector with Multiple Channel CapabilityB 854 98 (2004)3can count the number of error free seconds of transmissionversus the number of seconds during which an error occurred.6.6.1 The effect of various environmental stresses on per-formance may be evaluated as part of the test. For ex
48、ample, thedevice may be subjected to thermal cycling or mechanicaldisturbance while the error rate is being monitored.6.6.2 A number of commercial instruments are available toperform the measurement and error rate calculation functions.Some instruments simulate specific signal formats enablingevalua
49、tion of interconnection devices with signals typical ofthe application environment. For example, instruments areavailable to simulate DS1 and DS3 signaling formats used intelecommunications.86.6.3 Fig. 4 shows a schematic representation of an exampleof how this method may be implemented. In the instrumentillustrated, the connection or switch in the device under test iswired into a cable connecting the send and receive terminalsfor each channel. The instrument itself monitors the connectionand measures performance for the particular signal or datatransmission format being e
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