ASTM A698/A698M-20

Standard Test Method for Magnetic Shield Efficiency in Attenuating Alternating Magnetic Fields

SIGNIFICANCE AND USE
5.1 This test method provides an easy, accurate, and reproducible method for determination of shielding factors (attenuation ratios) in simple alternating magnetic fields.  
5.2 Since the sensing or pickup coil is of finite size, the measured shielding factor tends to be the average value for the space enclosed by the coil. Due care is required when interpreting results when the coil is located near an opening in the shield.  
5.3 This test method is suitable for design, specification acceptance, service evaluation, quality assurance, and research purposes on magnetic shields.  
5.4 Provided geometrically identical shields are compared, this test method is also suitable for evaluation and grading of magnetic shielding materials.
SCOPE
1.1 This test method covers the means for determining the performance quality of a magnetic shield when placed in a magnetic field of alternating polarity.  
1.2 This test method provides a means of evaluating and grading magnetic shielding materials to determine their suitability for use in the production of magnetic shields.  
1.3 This test method shall be used in conjunction with and shall conform to the requirements of Practice A34/A34M.  
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.  
1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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.

General Information

• Status: Published
• Publication Date: 31-May-2020
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• Technical Committee: A06 - Magnetic Properties
• Drafting Committee: A06.01 - Test Methods

Standards Content (Sample)

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: A698/A698M − 20
Standard Test Method for
Magnetic Shield Efficiency in Attenuating Alternating
1
Magnetic Fields
This standard is issued under the fixed designationA698/A698M; 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 A340 Terminology of Symbols and Definitions Relating to
Magnetic Testing
1.1 This test method covers the means for determining the
performance quality of a magnetic shield when placed in a
3. Terminology
magnetic field of alternating polarity.
3.1 The following symbols and abbreviated definitions ap-
1.2 This test method provides a means of evaluating and
plyonlytothistestmethod(theofficialsymbolsanddefinitions
grading magnetic shielding materials to determine their suit-
are listed in Terminology A340):
ability for use in the production of magnetic shields.
3.2 Definitions of Terms Specific to This Standard:
1.3 This test method shall be used in conjunction with and
3.2.1 attenuation ratio—the ratio of the measured voltage in
shall conform to the requirements of Practice A34/A34M.
thepickupcoilbeforeandaftertheinsertionoftheshieldunder
1.4 The values stated in either SI units or inch-pound units
test, E /E .
1 2
are to be regarded separately as standard. The values stated in
3.3 Abbreviations:
each system may not be exact equivalents; therefore, each
3.3.1 A—ac ammeter (usually root mean square (rms) but
system shall be used independently of the other. Combining
may be peak reading type).
values from the two systems may result in non-conformance
with the standard.
3.3.2 E —voltage in the pickup coil, after establishing the
1
field of test but before insertion of the shield into the test
1.5 This standard does not purport to address all of the
position.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3.3.3 E —highest voltage observed in the pickup coil, at the
2
priate safety, health, and environmental practices and deter-
field of test, while rotating the test shield in the test position.
mine the applicability of regulatory limitations prior to use.
3.3.4 H —magnetic field strength, Oe [A/m].
p
1.6 This international standard was developed in accor-
3.3.5 I —ac magnetizing current, peak amperes.
p
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
3.3.6 I—ac magnetizing current, rms amperes.
Development of International Standards, Guides and Recom-
3.3.7 l —length of demagnetizing air coil, cm [m].
c
mendations issued by the World Trade Organization Technical
3.3.8 N—number of turns per coil section (one half of total
Barriers to Trade (TBT) Committee.
Helmholtz coil turns).
2. Referenced Documents 3.3.9 N —number of turns in demagnetizing coil.
1
2
2.1 ASTM Standards: 3.3.10 R—mean radius of Helmholtz coil, cm [m].
A34/A34M Practice for Sampling and Procurement Testing
3.3.11 V—electronic voltmeter (average volts 3π/2 =2).
of Magnetic Materials
4. Summary of Test Method
1 4.1 Frequency—Tests under this test method are normally
This test method is under the jurisdiction of ASTM Committee A06 on
MagneticPropertiesandisthedirectresponsibilityofSubcommitteeA06.01onTest conducted at a test frequency of 60 Hz.
Methods.
NOTE 1—Other test frequencies are used by mutual agreement. In
CurrenteditionapprovedJune1,2020.PublishedJuly2020.Originallyapproved
in 1974. Last previous edition approved in 2015 as A698/A698M – 15. DOI: general, as test frequencies are increased, it will be necessary to make
10.1520/A0698_A0698M-20. corresponding changes in pickup or test coils and in the size of the power
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
supply.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
4.2 Magnetic Field Strength—Tests may be conducted at
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. any desired magnetic field strength. The standard test level for
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
A698/A698M − 20
ac magnetic fields is 0.5 or 2.0 peak Oe [39.8 or 159 peakA/m]
and in the presence of the earth’s magnetic field (see 9.2).
4.3 Instrumentation—The instruments described are for use
at 60 Hz. At higher frequencies, electronic voltmeter
...

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: A698/A698M − 15 A698/A698M − 20
Standard Test Method for
Magnetic Shield Efficiency in Attenuating Alternating
1
Magnetic Fields
This standard is issued under the fixed designation A698/A698M; 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 This test method covers the means for determining the performance quality of a magnetic shield when placed in a magnetic
field of alternating polarity.
1.2 This test method provides a means of evaluating and grading magnetic shielding materials to determine their suitability for
use in the production of magnetic shields.
1.3 This test method shall be used in conjunction with and shall conform to the requirements of Practice A34/A34M.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
1.5 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.6 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.
2. Referenced Documents
2
2.1 ASTM Standards:
A34/A34M Practice for Sampling and Procurement Testing of Magnetic Materials
A340 Terminology of Symbols and Definitions Relating to Magnetic Testing
3. Terminology
3.1 The following symbols and abbreviated definitions apply only to this test method (the official symbols and definitions are
listed in Terminology A340):
3.2 Definitions of Terms Specific to This Standard:
3.2.1 attenuation ratio—the ratio of the measured voltage in the pickup coil before and after the insertion of the shield under
test, E /E .
1 2
3.3 Abbreviations:
3.3.1 A—ac ammeter (usually root mean square (rms) but may be peak reading type).
3.3.2 E —voltage in the pickup coil, after establishing the field of test but before insertion of the shield into the test position.
1
3.3.3 E —highest voltage observed in the pickup coil, at the field of test, while rotating the test shield in the test position.
2
3.3.4 H —magnetic field strength, Oe [A/m].
p
3.3.5 I —ac magnetizing current, peak amperes.
p
3.3.6 I—ac magnetizing current, rms amperes.
1
This test method is under the jurisdiction of ASTM Committee A06 on Magnetic Properties and is the direct responsibility of Subcommittee A06.01 on Test Methods.
Current edition approved April 1, 2015June 1, 2020. Published May 2015July 2020. Originally approved in 1974. Last previous edition approved in 20072015 as
A698/A698MA698/A698M – 15.–07. DOI: 10.1520/A0698_A0698M-15.10.1520/A0698_A0698M-20.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
A698/A698M − 20
3.3.7 l —length of demagnetizing air coil, cm [m].
c
3.3.8 N—number of turns per coil section (one half of total Helmholtz coil turns).
3.3.9 N —number of turns in demagnetizing coil.
1
3.3.10 R—mean radius of Helmholtz coil, cm [m].
3.3.11 V—electronic voltmeter (average volts 3π/2 =2).
4. Summary of Test Method
4.1 Frequency—Tests under this test method are normally conducted at a test frequency of 60 Hz.
NOTE 1—Other test frequencies are used by mutual agreement. In general, as test frequencies are increased, it will be necessary to make corresponding
changes in pickup or test coils and in the size of the power supply.
4.2 Magnetic Field Strength—Tests may be conducted at any desired magnetic field strength. The standard test
...