ASTM A343/A343M-03(2008)
(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
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.
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 A 34/A 34M.
1.3 This test method 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 A 340.
1.7 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. Within this standard, SI units are shown in brackets except in the sections concerning calculations where there are separate sections for the respective unit systems.
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 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: A343/A343M − 03(Reapproved 2008)
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 values from the two systems may result in non-conformance
with the standard. Within this standard, SI units are shown in
1.1 Thistestmethodcoverstestsforthemagneticproperties
brackets except in the sections concerning calculations where
ofbasicflat-rolledmagneticmaterialsatpowerfrequencies(25
there are separate sections for the respective unit systems.
to 400 Hz) using a 25-cm Epstein test frame and the 25-cm
1.8 This standard does not purport to address all of the
double-lap-jointed core. It covers the determination of core
safety concerns, if any, associated with its use. It is the
loss, rms exciting power, rms and peak exciting current, and
responsibility of the user of this standard to establish appro-
several types of ac permeability and related properties of
priate safety and health practices and determine the applica-
flat-rolled magnetic materials under ac magnetization.
bility of regulatory limitations prior to use.
1.2 This test method shall be used in conjunction with
Practice A34/A34M.
2. Referenced Documents
1.3 This test method provides a test for core loss and
2.1 ASTM Standards:
exciting current at moderate and high magnetic flux densities
A34/A34MPractice for Sampling and Procurement Testing
up to 15 kG [1.5T] on nonoriented electrical steels and up to
of Magnetic Materials
18 kG [1.8T] on grain-oriented electrical steels.
A340Terminology of Symbols and Definitions Relating to
Magnetic Testing
1.4 Thefrequencyrangeofthistestmethodisnormallythat
A677Specification for Nonoriented Electrical Steel Fully
of the commercial power frequencies 50 to 60 Hz.With proper
Processed Types
instrumentation,itisalsoacceptableformeasurementsatother
A683Specification for Nonoriented Electrical Steel, Semi-
frequencies from 25 to 400 Hz.
processed Types
1.5 This test method also provides procedures for calculat-
A876Specification for Flat-Rolled, Grain-Oriented, Silicon-
ing ac impedance permeability from measured values of rms
Iron, Electrical Steel, Fully Processed Types
exciting current and for ac peak permeability from measured
A889/A889MTest Method for Alternating-Current Mag-
peak values of total exciting currents at magnetic field
netic Properties of Materials at Low Magnetic Flux
strengths up to about 150 Oe [12 000 A/m].
Density Using the Voltmeter-Ammeter-Wattmeter-
1.6 Explanation of symbols and abbreviated definitions
Varmeter Method and 25-cm Epstein Frame
appear in the text of this test method. The official symbols and
E177Practice for Use of the Terms Precision and Bias in
definitions are listed in Terminology A340.
ASTM Test Methods
E691Practice for Conducting an Interlaboratory Study to
1.7 The values stated in either SI units or inch-pound units
Determine the Precision of a Test Method
are to be regarded separately as standard. The values stated in
E1338Guide for Identification of Metals and Alloys in
each system may not be exact equivalents; therefore, each
Computerized Material Property Databases
system shall be used independently of the other. Combining
3. Significance and Use
1 3.1 Thistestmethodisafundamentalmethodforevaluating
This test method is under the jurisdiction of ASTM Committee A06 on
MagneticPropertiesandisthedirectresponsibilityofSubcommitteeA06.01onTest
the magnetic performance of flat-rolled magnetic materials in
Methods.
either as-sheared or stress-relief annealed condition.
Current edition approved May 1, 2008. Published June 2008. Originally
approved in 1949. Last previous edition approved in 2003 as A343/A343M-03.
DOI: 10.1520/A0343_A0343M-03R08. 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 − 03 (2008)
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
component parts as are required to perform the desired
4. Test Specimens
measurement functions:
4.1 The specimens for this test shall be selected and
6.2 Epstein Test Frame:
prepared for testing in accordance with provisions of Practice
6.2.1 The test frame shall consist of four solenoids (each
A34/A34M and as directed in Appendix of this test method.
having two windings) surrounding the four sides of the square
5. Basic Circuit magnetic circuit, and a mutual inductor to compensate for air
flux within the solenoids. The solenoids shall be wound on
5.1 Fig. 1 shows the essential apparatus and basic circuit
nonmagnetic, nonconducting forms of rectangular cross sec-
connections for this test method. Terminals 1 and 2 are
tionappropriatetothespecimenmasstobeused.Thesolenoids
connected to a source of adjustable ac voltage of sinusoidal
shall be mounted so as to be accurately in the same horizontal
waveform and sufficient power rating to energize the primary
plane,andwiththecenterlineofsolenoidsonoppositesidesof
circuit without appreciable voltage drop in the source imped-
the square, 250 6 0.3 mm apart. The compensating mutual
ance. All primary circuit switches and all primary wiring
inductor may be located in the center of the space enclosed by
should be capable of carrying much higher currents than are
the four solenoids if the axis of the inductor is made to be
normally encountered to limit primary circuit resistance to
perpendicular to the plane of the solenoid windings.
values that will not cause appreciable distortion of the flux
6.2.2 The inner or potential winding on each solenoid shall
waveform in the specimen when relatively nonsinusoidal
consist of one fourth of the total number of secondary turns
currents are drawn. The ac source may be an electronic
evenlywoundinonelayeroverawindinglengthof191mmor
amplifier which has a sine-wave oscillator connected to its
longer of each solenoid. The potential windings of the four
input and may include the necessary circuitry to maintain a
solenoids shall be connected in series so their voltages will
sinusoidal flux waveform by using negative feedback of the
add.Theouterormagnetizingwindinglikewiseshallconsistof
induced secondary voltage. In this case, higher primary resis-
one fourth of the total number of primary turns evenly wound
tance can be tolerated since this system will maintain sinusoi-
over the winding length of each solenoid. These individual
dal flux at much higher primary resistance. Although the
solenoid windings, too, shall be connected in series so their
current drain in the secondary is quite small, especially when
magnetic field strengths will add. The primary winding may
using modern high-input impedance instrumentation, the
compriseuptothreelayersusingtwoormorewiresinparallel.
switches and wiring should be selected to minimize the lead
resistance so that the voltage available at the terminals of the 6.2.3 Primary and secondary turns shall be wound in the
instruments is imperceptibly lower than the voltage at the same direction, with the starting end of each winding being at
secondary terminals of the Epstein test frame. the same corner junction of one of the four solenoids. This
FIG. 1 Basic Circuit for Wattmeter-Ammeter-Voltmeter Method
A343/A343M − 03 (2008)
enables the potential between adjacent primary and secondary ters is desirable to minimize loading effects and to reduce the
turns to be a minimum throughout the length of the winding, magnitude of instrument loss compensations. The input resis-
thereby reducing errors as a result of electrostatic phenomena. tance of an analog rms voltmeter shall not be less than 5000
Ω/V of full-scale indication.
6.2.4 The solenoid windings on the test frame may be any
number of turns suited to the instrumentation, mass of speci-
6.5 Wattmeter, W—The full-scale accuracy of the wattmeter
men, and test frequency.Windings with a total of 700 turns are
must not be poorer than 0.25% at the frequency of test and at
recommended for tests in the frequency range of 25 through
unity power factor. The power factor encountered by a watt-
400 Hz.
meter during a core loss test on a specimen is always less than
6.2.5 The mutual inductance of the air-flux compensating
unity and, at magnetic flux densities far above the knee of the
inductor shall be adjusted to be the same as that between the
magnetization curve, approaches zero. The wattmeter must
test-frame windings to within one turn of the compensator
maintainadequateaccuracy(1.0%ofreading)evenatthemost
secondary. Its windings shall be connected in series with the
severe (lowest) power factor that is presented to it. Variable
corresponding test-frame windings so that the voltage induced
scaling devices may be used to cause the wattmeter to indicate
inthesecondarywindingoftheinductorbytheprimarycurrent
directlyinunitsofspecificcorelossifthecombinationofbasic
will completely oppose or cancel the total voltage induced in
instrument and scaling devices conforms to the specifications
the secondary winding of the test frame when no sample is in
stated here.
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
dynamometer is recommended among this class of instru-
measuringtheextremelynonsinusoidal(peaked)voltagethatis
ments, but, if the specimen mass is sufficiently large, a
induced in the secondary winding of the mutual inductor.
direct-indicating electrodynamometer wattmeter of the highest
Additionally, if so used, an analog flux voltmeter should have
availablesensitivityandlowestpower-factorcapabilitymaybe
a minimum input resistance of 5000 Ω/V of full-scale indica-
used.
tion.
6.5.2.1 The sensitivity of the electrodynamometer wattme-
6.4 RMS Voltmeter, V —A true rms-indicating voltmeter ter must be such that the connection of the potential circuit of
rms
shall be provided for evaluating the form factor of the voltage the wattmeter, during testing, to the secondary winding of the
induced in the secondary winding of the test fixture and for test fixture does not change the terminal voltage of the
evaluating the instrument losses. The accuracy of the rms secondary by more than 0.05%. Also, the resistance of the
voltmeter shall be the same as that specified for the flux potential circuit of the wattmeter must be sufficiently high that
voltmeter. Either digital or analog rms voltmeters are permit- the inductive reactance of the potential coil of the wattmeter in
ted.The normally high-input impedance of digita
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