ASTM B542-13
(Terminology)Standard Terminology Relating to Electrical Contacts and Their Use
Standard Terminology Relating to Electrical Contacts and Their Use
SIGNIFICANCE AND USE
2.1 The terms in this standard are used in standards and literature related to electric contacts, materials for electric contacts and test methods for evaluating electric contacts. These terms may be difficult to locate in a general purpose dictionary or the definition in such a dictionary may not cover the meaning applied in the field of electric contacts.
SCOPE
1.1 The terms included in this list are those that are peculiar to electric contacts or general terms that have a specific meaning when related to electric contacts. The definitions were prepared assuming that the reader has a general knowledge in a physical science but is unfamiliar with the terminology of the literature of electric contacts.
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Designation: B542 − 13
Standard Terminology Relating to
1
Electrical Contacts and Their Use
This standard is issued under the fixed designation B542; 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 arc, cathode—the arc that occurs at greater than a critical
electrode spacing (see arc, anode), and results in cathode
1.1 The terms included in this list are those that are peculiar
material loss.
to electric contacts or general terms that have a specific
meaning when related to electric contacts.The definitions were
arc, shortest—a limiting state of an arc in which the total arc
prepared assuming that the reader has a general knowledge in
voltage approaches the sum of the cathode and anode falls.
a physical science but is unfamiliar with the terminology of the
blowout—the displacement and lengthening of an arc to
literature of electric contacts.
facilitate its extinction. The blowout effect can be achieved
2. Significance and Use
by a magnetic field, air blast, etc.
2.1 The terms in this standard are used in standards and
brush—a sliding contact member consisting of one or more
literature related to electric contacts, materials for electric
sliders (see sliders).
contacts and test methods for evaluating electric contacts.
These terms may be difficult to locate in a general purpose
cathode fall—the potential difference between the cathode and
dictionary or the definition in such a dictionary may not cover the electric discharge plasma.
the meaning applied in the field of electric contacts.
cathodic (cathode) material transfer—see material transfer.
3. Terminology
constriction resistance—the increase in resistance arising
from a change in current density distribution. In electric
a-spot—the areas of two mating contacts through which
contacts it is that portion of contact resistance resulting from
current flows from one contact to the other.
the convergence of current into the a-spots.
activation—aprocessinwhichcontaminationofthesurfaceof
contact, n—(a) a generic term that applies to a device or part
contacts causes arcing at lower than usual voltage or arcing
of a device and that has the capability of completing or
persists at lower than usual current, or both. For example,
interrupting the flow of an electrical signal in a circuit, (b)
palladium contacts operated in an organic vapor produce
may also be used with modifiers such as: electrical contact,
arcs at voltage and current less than the minimum arcing
arcing contact, noble metal contact, separable contact, etc.
voltage and current because of the presence of carbon on the
contact surfaces.
contact, adj—contact area, the part of an electrical device that
is actually touching and where the electrical signal is
anode fall—the potential difference between the anode and the
expected to pass. Contact member, one of the electrical path
electrical discharge plasma.
parts that can make or break an electrical path.
anodic (anode) material transfer—see material transfer.
contact, arcing—an electrical contact whose primary mode of
arc discharge—a self-sustaining, high current density, high
wearout occurs on the contacting surfaces as a result of an
temperature discharge, uniquely characterized by a cathode
arc formed between separating or closing contact pairs.
fall nearly equal to the ionization potential of the gas or
vapor in which it exists.
contact bounce—the unwanted operation of contacts immedi-
ately following intentional operation.
arc, anode—the arc that occurs at less than a critical electrode
spacing (see arc, cathode), and results in anode material
contact(s), butting—a type of contacts in which the direction
loss.
of the motion of the moving contact is perpendicular to the
contact faces. The contacts close and open with no appre-
1
This terminology is under the jurisdiction of ASTM Committee B02 on
ciable sliding or rolling action.
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee
B02.05 on Precious Metals and Electrical Contact Materials.
contact chatter—the unwanted operation of contacts resulting
Current edition approved Feb. 1, 2013. Published March 2013. Originally
from external forces operating on them. For example,
approved in 1932. Last previous edition approved in 2007 as B542 – 07. DOI:
10.1520/B0542-13. vibration may cause contacts to open and close or “chatter.”
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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B542 − 13
contact-closing force—the transient force between contacts conta
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This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B542 − 07 B542 − 13
Standard Terminology Relating to
1
Electrical Contacts and Their Use
This standard is issued under the fixed designation B542; 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
1.1 The terms included in this list are those that are peculiar to electric contacts or general terms that have a specific meaning
when related to electric contacts. The definitions were prepared assuming that the reader has a general knowledge in a physical
science but is unfamiliar with the terminology of the literature of electric contacts.
2. Significance and Use
2.1 The terms in this standard are used in standards and literature related to electric contacts, materials for electric contacts and
test methods for evaluating electric contacts. These terms may be difficult to locate in a general purpose dictionary or the definition
in such a dictionary may not cover the meaning applied in the field of electric contacts.
3. Terminology
a-spot—the areas of two mating contacts through which current flows from one contact to the other.
activation—a process in which contamination of the surface of contacts causes arcing at lower than usual voltage or arcing persists
at lower than usual current, or both. For example, palladium contacts operated in an organic vapor produce arcs at voltage and
current less than the minimum arcing voltage and current because of the presence of carbon on the contact surfaces.
anode fall—the potential difference between the anode and the electrical discharge plasma.
anodic (anode) material transfer—see material transfer.
arc discharge—a self-sustaining, high current density, high temperature discharge, uniquely characterized by a cathode fall nearly
equal to the ionization potential of the gas or vapor in which it exists.
arc, anode—the arc that occurs at less than a critical electrode spacing (see arc,cathode), and results in anode material loss.
arc, cathode—the arc that occurs at greater than a critical electrode spacing (see arc,anode), and results in cathode material loss.
arc, shortest—a limiting state of an arc in which the total arc voltage approaches the sum of the cathode and anode falls.
blowout—the displacement and lengthening of an arc to facilitate its extinction. The blowout effect can be achieved by a magnetic
field, air blast, etc.
brush—a sliding contact member consisting of one or more sliders (see sliders).
cathode fall—the potential difference between the cathode and the electric discharge plasma.
cathodic (cathode) material transfer—see material transfer.
constriction resistance—the increase in resistance arising from a change in current density distribution. In electric contacts it is
that portion of contact resistance resulting from the convergence of current into the a-spots.
contact, n—(a)(a) a generic term that applies to a device or part of a device and that has the capability of completing or interrupting
the flow of an electrical signal in a circuit, (b)(b) may also be used with modifiers such as: electrical contact, arcing contact,
noble metal contact, separable contact, etc.
1
This terminology is under the jurisdiction of ASTM Committee B02 on Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee B02.91 on
Editorial and Terminology.
Current edition approved May 1, 2007Feb. 1, 2013. Published May 2007March 2013. Originally approved in 1932. Last previous edition approved in 20042007 as
B542 – 04.B542 – 07. DOI: 10.1520/B0542-07.10.1520/B0542-13.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
B542 − 13
contact, adj—contact area, the part of an electrical device that is actually touching and where the electrical signal is expected to
pass. Contact member, one of the electrical path parts that can make or break an electrical path.
contact, arcing—an electrical contact whose primary mode of wearout occurs on the contacting surfaces as a result of an arc
formed between separating or closing contact pairs.
contact bounce—the unwanted operation of contacts immediately following intentional operation.
contact(s), butting—a type of contacts in which the direction of the motion of the moving contact is perpendicular to the cont
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