ASTM A343/A343M-14(2019)
(Test Method)Standard Test Method for Alternating-Current Magnetic Properties of Materials at Power Frequencies Using Wattmeter-Ammeter-Voltmeter Method and 25-cm Epstein Test Frame
Standard Test Method for Alternating-Current Magnetic Properties of Materials at Power Frequencies Using Wattmeter-Ammeter-Voltmeter Method and 25-cm Epstein Test Frame
SIGNIFICANCE AND USE
3.1 This test method is a fundamental method for evaluating the magnetic performance of flat-rolled magnetic materials in either as-sheared or stress-relief annealed condition.
3.2 This test method is suitable for design, specification acceptance, service evaluation, and research and development.
SCOPE
1.1 This test method covers tests for the magnetic properties of basic flat-rolled magnetic materials at power frequencies (25 to 400 Hz) using a 25-cm Epstein test frame and the 25-cm double-lap-jointed core. It covers the determination of core loss, rms exciting power, rms and peak exciting current, and several types of ac permeability and related properties of flat-rolled magnetic materials under ac magnetization.
1.2 This test method shall be used in conjunction with Practice A34/A34M.
1.3 This test method2 provides a test for core loss and exciting current at moderate and high magnetic flux densities up to 15 kG [1.5 T] on nonoriented electrical steels and up to 18 kG [1.8 T] on grain-oriented electrical steels.
1.4 The frequency range of this test method is normally that of the commercial power frequencies 50 to 60 Hz. With proper instrumentation, it is also acceptable for measurements at other frequencies from 25 to 400 Hz.
1.5 This test method also provides procedures for calculating ac impedance permeability from measured values of rms exciting current and for ac peak permeability from measured peak values of total exciting currents at magnetic field strengths up to about 150 Oe [12 000 A/m].
1.6 Explanation of symbols and abbreviated definitions appear in the text of this test method. The official symbols and definitions are listed in Terminology A340.
1.7 The values and equations stated in customary (cgs-emu and inch-pound) or SI units are to be regarded separately as standard. Within this standard, SI units are shown in brackets except for the sections concerning calculations where there are separate sections for the respective unit systems. 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 this standard.
1.8 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.
1.9 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
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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: A343/A343M − 14 (Reapproved 2019)
Standard Test Method for
Alternating-Current Magnetic Properties of Materials at
Power Frequencies Using Wattmeter-Ammeter-Voltmeter
Method and 25-cm Epstein Test Frame
This standard is issued under the fixed designationA343/A343M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope separate sections for the respective unit systems. The values
stated in each system may not be exact equivalents; therefore,
1.1 Thistestmethodcoverstestsforthemagneticproperties
each system shall be used independently of the other. Combin-
ofbasicflat-rolledmagneticmaterialsatpowerfrequencies(25
ing values from the two systems may result in non-
to 400 Hz) using a 25-cm Epstein test frame and the 25-cm
conformance with this standard.
double-lap-jointed core. It covers the determination of core
1.8 This standard does not purport to address all of the
loss, rms exciting power, rms and peak exciting current, and
safety concerns, if any, associated with its use. It is the
several types of ac permeability and related properties of
responsibility of the user of this standard to establish appro-
flat-rolled magnetic materials under ac magnetization.
priate safety, health, and environmental practices and deter-
1.2 This test method shall be used in conjunction with
mine the applicability of regulatory limitations prior to use.
Practice A34/A34M.
1.9 This international standard was developed in accor-
1.3 This test method provides a test for core loss and
dance with internationally recognized principles on standard-
exciting current at moderate and high magnetic flux densities
ization established in the Decision on Principles for the
up to 15 kG [1.5T] on nonoriented electrical steels and up to
Development of International Standards, Guides and Recom-
18 kG [1.8T] on grain-oriented electrical steels.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.4 Thefrequencyrangeofthistestmethodisnormallythat
ofthecommercialpowerfrequencies50to60Hz.Withproper
2. Referenced Documents
instrumentation,itisalsoacceptableformeasurementsatother
frequencies from 25 to 400 Hz.
2.1 ASTM Standards:
A34/A34MPractice for Sampling and Procurement Testing
1.5 This test method also provides procedures for calculat-
of Magnetic Materials
ing ac impedance permeability from measured values of rms
A340Terminology of Symbols and Definitions Relating to
exciting current and for ac peak permeability from measured
Magnetic Testing
peak values of total exciting currents at magnetic field
A677Specification for Nonoriented Electrical Steel Fully
strengths up to about 150 Oe [12 000 A/m].
Processed Types
1.6 Explanation of symbols and abbreviated definitions
A683Specification for Nonoriented Electrical Steel, Semi-
appear in the text of this test method. The official symbols and
processed Types
definitions are listed in Terminology A340.
A876Specification for Flat-Rolled, Grain-Oriented, Silicon-
1.7 The values and equations stated in customary (cgs-emu Iron, Electrical Steel, Fully Processed Types
and inch-pound) or SI units are to be regarded separately as A889/A889MTest Method for Alternating-Current Mag-
standard. Within this standard, SI units are shown in brackets netic Properties of Materials at Low Magnetic Flux
except for the sections concerning calculations where there are Density Using the Voltmeter-Ammeter-Wattmeter-
Varmeter Method and 25-cm Epstein Frame
E177Practice for Use of the Terms Precision and Bias in
This test method is under the jurisdiction of ASTM Committee A06 on
ASTM Test Methods
MagneticPropertiesandisthedirectresponsibilityofSubcommitteeA06.01onTest
E691Practice for Conducting an Interlaboratory Study to
Methods.
Current edition approved April 1, 2019. Published April 2019. Originally
approved in 1949. Last previous edition approved in 2014 as A343/A343M–14.
DOI: 10.1520/A0343_A0343M-14R19. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Burgwin, S. L., “Measurement of Core Loss and A-C Permeability with the contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
25-cm Epstein Frame,” Proceedings, American Society for Testing and Materials, Standards volume information, refer to the standard’s Document Summary page on
ASTEA, Vol 41, 1941, p. 779. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A343/A343M − 14 (2019)
Determine the Precision of a Test Method tance can be tolerated since this system will maintain sinusoi-
E1338Guide for Identification of Metals and Alloys in dal flux at much higher primary resistance. Although the
Computerized Material Property Databases current drain in the secondary is quite small, especially when
using modern high-input impedance instrumentation, the
3. Significance and Use
switches and wiring should be selected to minimize the lead
resistance so that the voltage available at the terminals of the
3.1 Thistestmethodisafundamentalmethodforevaluating
instruments is imperceptibly lower than the voltage at the
the magnetic performance of flat-rolled magnetic materials in
either as-sheared or stress-relief annealed condition. secondary terminals of the Epstein test frame.
3.2 This test method is suitable for design, specification
6. Apparatus
acceptance, service evaluation, and research and development.
6.1 The apparatus shall consist of as many of the following
4. Test Specimens
component parts as are required to perform the desired
measurement functions:
4.1 The specimens for this test shall be selected and
prepared for testing in accordance with provisions of Practice
6.2 Epstein Test Frame:
A34/A34M and as directed in Annex A3 of this test method. 6.2.1 The test frame shall consist of four solenoids (each
having two windings) surrounding the four sides of the square
5. Basic Circuit
magnetic circuit, and a mutual inductor to compensate for air
5.1 Fig. 1 shows the essential apparatus and basic circuit flux within the solenoids. The solenoids shall be wound on
connections for this test method. Terminals 1 and 2 are nonmagnetic, nonconducting forms of rectangular cross sec-
connected to a source of adjustable ac voltage of sinusoidal tionappropriatetothespecimenmasstobeused.Thesolenoids
waveform and sufficient power rating to energize the primary shall be mounted so as to be accurately in the same horizontal
circuit without appreciable voltage drop in the source imped- plane,andwiththecenterlineofsolenoidsonoppositesidesof
ance. All primary circuit switches and all primary wiring the square, 250 6 0.3 mm apart. The compensating mutual
should be capable of carrying much higher currents than are inductor may be located in the center of the space enclosed by
normally encountered to limit primary circuit resistance to the four solenoids if the axis of the inductor is made to be
values that will not cause appreciable distortion of the flux perpendicular to the plane of the solenoid windings.
waveform in the specimen when relatively nonsinusoidal 6.2.2 The inner or potential winding on each solenoid shall
currents are drawn. The ac source may be an electronic consist of one fourth of the total number of secondary turns
amplifier which has a sine-wave oscillator connected to its evenlywoundinonelayeroverawindinglengthof191mmor
input and may include the necessary circuitry to maintain a longer of each solenoid. The potential windings of the four
sinusoidal flux waveform by using negative feedback of the solenoids shall be connected in series so their voltages will
induced secondary voltage. In this case, higher primary resis- add.Theouterormagnetizingwindinglikewiseshallconsistof
FIG. 1 Basic Circuit for Wattmeter-Ammeter-Voltmeter Method
A343/A343M − 14 (2019)
one fourth of the total number of primary turns evenly wound 6.4 RMS Voltmeter, V —A true rms-indicating voltmeter
rms
over the winding length of each solenoid. These individual shall be provided for evaluating the form factor of the voltage
solenoid windings, too, shall be connected in series so their
induced in the secondary winding of the test fixture and for
magnetic field strengths will add. The primary winding may evaluating the instrument losses. The accuracy of the rms
compriseuptothreelayersusingtwoormorewiresinparallel.
voltmeter shall be the same as that specified for the flux
6.2.3 Primary and secondary turns shall be wound in the
voltmeter. Either digital or analog rms voltmeters are permit-
same direction, with the starting end of each winding being at
ted.The normally high-input impedance of digital rms voltme-
the same corner junction of one of the four solenoids. This
ters is desirable to minimize loading effects and to reduce the
enables the potential between adjacent primary and secondary
magnitude of instrument loss compensations. The input resis-
turns to be a minimum throughout the length of the winding,
tance of an analog rms voltmeter shall not be less than 5000
thereby reducing errors as a result of electrostatic phenomena.
Ω/V of full-scale indication.
6.2.4 The solenoid windings on the test frame may be any
6.5 Wattmeter, W—The full-scale accuracy of the wattmeter
number of turns suited to the instrumentation, mass of
must not be poorer than 0.25% at the frequency of test and at
specimen, and test frequency. Windings with a total of 700
unity power factor. The power factor encountered by a watt-
turns are recommended for tests in the frequency range of 25
meter during a core loss test on a specimen is always less than
through 400 Hz.
unity and, at magnetic flux densities far above the knee of the
6.2.5 The mutual inductance of the air-flux compensating
magnetization curve, approaches zero. The wattmeter must
inductor shall be adjusted to be the same as that between the
maintainadequateaccuracy(1.0%ofreading)evenatthemost
test-frame windings to within one turn of the compensator
severe (lowest) power factor that is presented to it. Variable
secondary. Its windings shall be connected in series with the
scaling devices may be used to cause the wattmeter to indicate
corresponding test-frame windings so that the voltage induced
directlyinunitsofspecificcorelossifthecombinationofbasic
inthesecondarywindingoftheinductorbytheprimarycurrent
instrument and scaling devices conforms to the specifications
will completely oppose or cancel the total voltage induced in
stated here.
the secondary winding of the test frame when no sample is in
place in the solenoids. Specifications for the approximate turns 6.5.1 Electronic Digital Wattmeter—Electronic digital watt-
and construction details of the compensating mutual inductor
meters have been developed that have proven satisfactory for
for the standard test frame are given in Table A1.1 of Annex use under the provisions of this test method. Usage of a
A1.
suitable electronic digital wattmeter is permitted as an alterna-
tive to an electrodynamometer wattmeter in this test method.
6.3 Flux Voltmeter, V —Afull-wavetrue-average,voltmeter,
f
An electronic digital wattmeter oftentimes is preferred in this
with scale reading in average volts times =2 π/4 so that its
test method because of its digital readout and its capability for
indications will be identical with those of a true rms voltmeter
direct interfacing with electronic data acquisition systems.
on a pure sinusoidal voltage, shall be provided for evaluating
6.5.1.1 The voltage input circuitry of the electronic digital
thepeakvalueofthetestmagneticfluxdensity.Toproducethe
wattmeter must have an input impedance sufficiently high that
estimatedprecisionoftestunderthistestmethod,thefull-scale
connection of the circuitry, during testing, to the secondary
metererrorsshallnotexceed0.25%(Note1).Metersof0.5%
windingofthetestfixturedoesnotchangetheterminalvoltage
of more error may be used at reduced accuracy. Either digital
of the secondary by more than 0.05%. In addition, the voltage
or analog flux voltmeters are permitted. The normally high-
inputcircuitrymustbecapableofacceptingthemaximumpeak
input impedance of digital flux voltmeters is desirable to
voltagethatisinducedinthesecondarywindingduringtesting.
minimize loading effects and to reduce the magnitude of
instrument loss compensations. The input resistance of an
6.5.1.2 The current input circuitry of the electronic digital
analog flux voltmeter shall not be less than 1000 Ω/V of
wattmeter must have an input impedance of no more than 1Ω.
full-scale indication. A resistive voltage divider, a standard-
Preferably the input impedance should be no more than 0.1 Ω
ratio transformer, or other variable scaling device may be used
ifthefluxwaveformdistortionotherwisetendstobeexcessive.
to cause the flux voltmeter to indicate directly in units of
In addition, the current input circuitry must be capable of
magnetic flux density if the combination of basic instrument
accepting the maximum rms current and the maximum peak
and scaling device conforms to the specifications stated above.
current drawn by the primary winding of the test fixture when
NOTE1—Inaccuraciesinsettingthetestvoltageproduceerrorsapproxi-
core loss tests are being performed. In particular, since the
mately two times as large in the specific core loss. Voltage scales should
primary current will be very nonsinusoidal (peaked) if core-
be such that the instrument is not used at less than half scale. Care should
loss tests are performed on a specimen at magnetic flux
also be taken to avoid errors caused by temperature and frequency effects
densities above the knee of the magnetization curve, the crest
in the instrument.
factor capability of the current input circuitry should be three
6.3.1 If used with a mutual inductor as a peak ammeter at
or more.
magnetic flux densities well above the knee of the magnetiza-
6.5.2 Electrodynamometer Wattmeter—A reflecting-type
tion curve, the flux voltmeter must be capable of accurately
measuringtheextremelynonsinusoidal(peaked)voltagethatis dynamometer is recommended among this class of
instruments, but, if the specimen mass is sufficiently large, a
induced in the secondary winding of the mutual inductor.
Additionally, if so used, an analog flux voltmeter should have direct-indicating electrodynamometer wattmeter of the highest
availablesensitivityandl
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