ASTM B854-98(2004)
(Guide)Standard Guide for Measuring Electrical Contact Intermittences
Standard Guide for Measuring Electrical Contact Intermittences
SIGNIFICANCE AND USE
This guide suggests techniques to evaluate intermittences in a contact pair while it is subjected to simulated or actual environmental stress. Such measurements are a valuable tool in predicting circuit performance under these stress conditions and in diagnosing observed problems in circuit function under such conditions.
This document is intended to provide some general guidance on the best available practices for detecting, quantifying, characterizing and reporting short duration intermittences in circuits containing electrical contacts. Certain environmental stresses such as mechanical shock, vibration or temperature change may cause intermittences. These measurement procedures include methods applicable to contacts operating under various conditions in testing or in service.
Practice B 615 defines methods for measuring electrical contact noise in sliding electrical contacts. In contrast Guide B 854 provides guidance to the various methods for measuring similar phenomena in static contacts.
SCOPE
1.1 The techniques described in this guide apply to electrical circuits that include one or more electrical contacts in devices such as slip rings, separable connectors, electromechanical relays or closed switch contacts. The user should determine applicability for other devices.
1.2 The range of techniques described apply to circuit discontinuities (intermittences) of durations ranging from approximately 10 nanoseconds to several seconds and of sufficient magnitude to cause alteration of the circuit function. Extension of the guide to shorter duration events may be possible with suitable instrumentation. Events of longer duration may be monitored by techniques for dc measurements such as those described in Test Methods B539 or by adaptation of methods described in this guide.
1.3 The techniques described in this guide apply to electrical circuits carrying currents typical of signal circuits. Such currents are generally less than 100 ma. Extension of these techniques to circuits carrying larger currents may be possible, but the user should evaluate applicability first.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation:B854–98(Reapproved2004)
Standard Guide for
Measuring Electrical Contact Intermittences
This standard is issued under the fixed designation B854; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope B615 Practice for Measuring Electrical Contact Noise in
Sliding Electrical Contacts
1.1 The techniques described in this guide apply to electri-
B878 Test Method for Nanosecond Event Detection for
cal circuits that include one or more electrical contacts in
Electrical Contacts and Connectors
devices such as slip rings, separable connectors, electrome-
2.2 Other Documents:
chanical relays or closed switch contacts. The user should
IEC Publication 512, Test 2e Contact Disturbance
determine applicability for other devices.
EIA-364-46 Continuity Test Procedure for Electrical
1.2 The range of techniques described apply to circuit
Connectors
discontinuities (intermittences) of durations ranging from ap-
proximately 10 nanoseconds to several seconds and of suffi-
3. Terminology
cient magnitude to cause alteration of the circuit function.
3.1 Terms relevant to this guide are defined in Terminology
Extension of the guide to shorter duration events may be
B542 except as noted in the following section.
possible with suitable instrumentation. Events of longer dura-
3.2 Definitions of Terms Specific to This Standard:
tion may be monitored by techniques for dc measurements
3.2.1 intermittence—a transient increase in the voltage
such as those described inTest Methods B539 or by adaptation
drop across a pair of electrical contacts.
of methods described in this guide.
1.3 The techniques described in this guide apply to electri-
4. Significance and Use
cal circuits carrying currents typical of signal circuits. Such
4.1 This guide suggests techniques to evaluate intermit-
currents are generally less than 100 ma. Extension of these
tences in a contact pair while it is subjected to simulated or
techniques to circuits carrying larger currents may be possible,
actual environmental stress. Such measurements are a valuable
but the user should evaluate applicability first.
tool in predicting circuit performance under these stress
1.4 This standard does not purport to address all of the
conditions and in diagnosing observed problems in circuit
safety concerns, if any, associated with its use. It is the
function under such conditions.
responsibility of the user of this standard to become familiar
4.2 This document is intended to provide some general
with all hazards including those identified in the appropriate
guidance on the best available practices for detecting, quanti-
Material Safety Data Sheet (MSDS) for this product/material
fying, characterizing and reporting short duration intermit-
as provided by the manufacturer, to establish appropriate
tences in circuits containing electrical contacts. Certain envi-
safety and health practices, and determine the applicability of
ronmental stresses such as mechanical shock, vibration or
regulatory limitations prior to use.
temperature change may cause intermittences. These measure-
2. Referenced Documents ment procedures include methods applicable to contacts oper-
2 ating under various conditions in testing or in service.
2.1 ASTM Standards:
4.3 Practice B615 defines methods for measuring electrical
B539 Test Methods for Measuring Resistance of Electrical
contact noise in sliding electrical contacts. In contrast Guide
Connections (Static Contacts)
B854 provides guidance to the various methods for measuring
B542 Terminology Relating to Electrical Contacts and
similar phenomena in static contacts.
Their Use
5. Apparatus
This guide is under the jurisdiction of ASTM Committee B02 on Nonferrous 5.1 General Comments—The apparatus required varies de-
Metals and Alloys and is the direct responsibility of Subcommittee B02.11 on
pending upon the technique selected and the parameters (such
Electrical Contact Test Methods.
as duration and magnitude) of the intermittence that the user
Current edition approved May 1, 2004. Published May 2004. Originally
approved in 1998. Last previous edition approved in 1998 as B854 – 98. DOI:
10.1520/B0854-98R04.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
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Standards volume information, refer to the standard’s Document Summary page on Available from Electronic IndustriesAssociation, 2001 PennsylvaniaAve NW,
the ASTM website. Washington D.C. 20006.
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B854–98 (2004)
TABLE 1 Comparison of Methods of Monitoring Electrical Contact Intermittences
Typical Number
Method Typical Event Characterization Possible Advantages
of Channels
Oscilloscope 1, 2 or 4 DV vs time detailed characterization of each event
Custom Circuitry 1 per circuit Presence or absence of one or more events during a Ability to closely model actual circuit conditions,
preselected monitoring interval, such events defined allows use of various technologies in the transmitting
as above a preselected threshold of DR and duration, and receiving devices
the number of events during the interval may or may
not be recorded.
Event Detector 1 to 64 Presence or absence of one or more events during a Multichannel capability, selection of thresholds for
preselected monitoring interval, such events defined events to be counted
as above a preselected threshold of DR and duration,
but the number of events during the interval is not
recorded.
Bit Error Rate 1 ratio of errors to number of bits transmitted The format of the results is readily applicable to
ranking of interconnection devices with respect to
transmission quality for a specific signal format
series? If contacts cannot be connected in series, how many
contacts must be measured simultaneously?
6.2 Test results should be reported in a format appropriate
for the application and consistent with the format supplied by
the test instrument.
6.3 Oscilloscope—In this method, an oscilloscope is wired
to monitor the potential across the contact(s) of interest while
a signal is passed through the contacts. Standards such as IEC
Publication 512, Test 2e or EIA-364-46 are often implemented
using this method. Practice B615 provides a specific circuit
that uses this method. Examples of the use of this method are
FIG. 1 Schematic Representation of Oscilloscope Method
shown in the reference by Currence and Rhoades.
6.3.1 Fig. 1 shows a schematic representation of an
wants to detect. In general, the cabling must be capable of
example of how this method may be implemented. In selecting
carrying signals of the speed to be detected in the study, and
an oscilloscope, choose a model with response time fast
must be isolated from sources of noise that may cause false
enough to observe events of the duration of interest in the
indications.
study. The user may find it convenient to use an oscilloscope
5.2 Special Precautions for Measurements Involving Events
capable of storing and printing results.
Less than 1 Microsecond in Duration—Detection of events of
6.4 Custom Circuitry—In this method, the user assembles
duration less than 1 microsecond will require special attention
circuitry to measure the effects of the intermittences under the
to the wiring of the detection circuits and instrumentation.
conditions of interest. For example, the circuitry may simulate
Such attention may include using coaxial cable, shielding the
the type of source and detector circuitry that the user plans to
apparatus from interferences and minimizing cable lengths.
design into a system. Alternatively, the user may design
5.3 Specific Apparatus—The apparatus required will vary
circuitry based on specialized components to achieve capabili-
depending upon the measurement method selected and the
ties different from those found in commercial instruments. An
environmental stresses imposed during the test.
example of custom circuitry was described by Abbott and
Schreiber.
6. Procedure
6.4.1 Fig.2showsaschematicrepresentationofanexample
6.1 General Comments—The following sections describe,
of how this method may be implemented. The source and
in general terms, several methods that have been used to detect
detector incorporate the specific devices, technology, driver
or measure contact intermittences. The user should select an
circuits, amplifiers, etc., that are of interest in the intended
appropriate method and adapt it as required. Table 1 presents a
application of the connection or switch under test. The control
comparison of the attributes of the various methods. The
and
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