ASTM B576-94(2021)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B576 − 94 (Reapproved 2021)
Standard Guide for
Arc Erosion Testing of Electrical Contact Materials
This standard is issued under the fixed designation B576; 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 the manner in which the arc moves about on the surface of the
contact. A contact with a hemispherical crown presents no
1.1 This guide covers the major variables which affect the
sharp edges that would result in different amounts of erosion
rate of arc erosion of electrical contact materials and serves as
products for a given amount of arcing and aids in the control of
a guide in developing more detailed specifications for arc-
the arc when operating in air and other gases.
erosion tests.
3.1.2 The contacts may be given a type of normal shape and
1.2 Arc erosion testing involves some vaporization of ma-
surface roughness by a number of arcing operations prior to
terial. It is the responsibility of the user to become familiar
recording the contact loss. There may be a difference in the
with all hazards including those identified in the appropriate
effect of shape and diameter for different environments.
Material Safety Data Sheet for the material being tested.
3.1.3 Contact mounting, attachment, and bond integrity can
1.3 This standard does not purport to address all of the
affect the arc erosion of materials and should be specified.
safety concerns, if any, associated with its use. It is the
3.2 Contact Velocity and Maximum Arc Length—The veloc-
responsibility of the user of this standard to become familiar
ity of separation and the maximum arc length affect the erosion
with all hazards including those identified in the appropriate
rate and, therefore, should be specified in formulating a test.
Safety Data Sheet (SDS) for this product/material as provided
3.3 Contact Orientation:
by the manufacturer, to establish appropriate safety, health,
3.3.1 The orientation of the contacts with respect to the
and environmental practices, and determine the applicability
earth’s gravitational field may affect the erosion rate and,
of regulatory limitations prior to use.
therefore, should be specified. For example, the mating planes
1.4 This international standard was developed in accor-
of the contacts might be vertical or horizontal.
dance with internationally recognized principles on standard-
3.3.2 If the contact’s mating planes are horizontal and a
ization established in the Decision on Principles for the
direct test current is used, the specifications should state
Development of International Standards, Guides and Recom-
whether the anode or cathode is in the upper position.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
3.4 Environment:
3.4.1 The type, pressure, temperature, and humidity of the
2. Significance and Use
gas atmosphere or the type, pressure, and temperature of the
2.1 The significance of the variables set forth in this guide
surrounding oil, affect the erosion rate and should be specified.
was proved by various laboratories using several test systems
3.4.2 The erosion rate in air may be quite different than that
at test currents ranging from 100 to 35 000A. These variables
under oil.
will be significant for any case where voltage and current are
3.5 Arcing Current:
sufficient to produce arcing.
3.5.1 An increase in arc current will cause an increase in the
arc-erosion rate per coulomb of arcing, and thus it must be
3. Major Variables
specified.
3.1 Shape, Area, and Thickness:
3.5.2 It follows then that the wave form of the arc current is
3.1.1 The area, shape, and thickness of the contact affect the
important and source voltage and load current should be
erosion rates. As an example of shape effects, the radius of t
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