ASTM A343-97
(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
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.
1.3 This test method provides a test for core loss and exciting current at moderate and high inductions up to 15 kG (1.5T) on nonoriented electrical steels and up to 18 kG (1.8T) 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 magnetizing forces 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 stated in either customary (cgs-emu and inch-pound) units or SI units are to be regarded separately as standard. Within the text, the 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 are not exact equivalents; therefore, each system shall be used independently of the other. Combining values from the systems may result in nonconformance with this test method.
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)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
Designation: A 343 – 97
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 designation A 343; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope system shall be used independently of the other. Combining
values from the systems may result in nonconformance with
1.1 Thistestmethodcoverstestsforthemagneticproperties
this test method.
ofbasicflat-rolledmagneticmaterialsatpowerfrequencies(25
1.8 This standard does not purport to address all of the
to 400 Hz) using a 25-cm Epstein test frame and the 25-cm
safety concerns, if any, associated with its use. It is the
double-lap-jointed core. It covers the determination of core
responsibility of the user of this standard to establish appro-
loss, rms exciting power, rms and peak exciting current, and
priate safety and health practices and determine the applica-
several types of ac permeability and related properties of
bility of regulatory limitations prior to use.
flat-rolled magnetic materials under ac magnetization.
1.2 This test method shall be used in conjunction with
2. Referenced Documents
Practice A34.
3 2.1 ASTM Standards:
1.3 This test method provides a test for core loss and
A34 Practice for Sampling and Procurement Testing of
exciting current at moderate and high inductions up to 15 kG
Magnetic Materials
[1.5T]onnonorientedelectricalsteelsandupto18kG[1.8T]
A340 Terminology of Symbols and Definitions Relating to
on grain-oriented electrical steels.
Magnetic Testing
1.4 Thefrequencyrangeofthistestmethodisnormallythat
A347 Test Method forAlternating-Current Magnetic Prop-
of the commercial power frequencies 50 to 60 Hz.With proper
erties of Materials Using the Dieterly Bridge Method with
instrumentation,itisalsoacceptableformeasurementsatother
25-cm Epstein Frame
frequencies from 25 to 400 Hz.
A677 Specification for Nonoriented Electrical Steel Fully
1.5 This test method also provides procedures for calculat-
Processed Types
ing ac impedance permeability from measured values of rms
A 677M Specification for Nonoriented Electrical Steel,
exciting current and for ac peak permeability from measured
Fully Processed Types (Metric)
peak values of total exciting currents at magnetizing forces up
A683 Specification for Nonoriented Electrical Steel, Semi-
to about 150 Oe [12 000 A/m].
processed Types
1.6 Explanation of symbols and abbreviated definitions
A 683M Specification for Nonoriented Electrical Steel,
appear in the text of this test method. The official symbols and
Semiprocessed Types (Metric)
definitions are listed in Terminology A340.
A 876 Specification for Flat-Rolled, Grain-Oriented,
1.7 The values stated in either customary (cgs-emu and
Silicon-Iron, Electrical Steel, Fully Processed Types
inch-pound) units or SI units are to be regarded separately as
A 876M Specification for Flat-Rolled, Grain-Oriented,
standard. Within the text, the SI units are shown in brackets
Silicon-Iron, Electrical Steel, Fully ProcessedTypes (Met-
except for the sections concerning calculations where there are
ric)
separate sections for the respective unit systems. The values
A889 Test Method forAlternating-Current Magnetic Prop-
stated in each system are not exact equivalents; therefore, each
ertiesofMaterialsatLowInductionsUsingtheWattmeter-
Varmeter-Ammeter-Voltmeter Method and 25-cm (250-
This test method is under the jurisdiction of ASTM Committee A06 on mm) Epstein Frame
Magnetic Properties and is the direct responsibility of SubcommitteeA6.01 on Test
E177 Practice for Use of the Terms Precision and Bias in
Methods.
ASTM Test Methods
Current edition approved April 10, 1997. Published December 1997. Originally
E691 Practice for Conducting an Interlaboratory Study to
published as A343–49. Last previous edition A343–93a.
Annual Book of ASTM Standards, Vol 03.04.
SeeBurgwin,S.L.,“MeasurementofCoreLossandA-CPermeabilitywiththe
25-cm Epstein Frame,” Proceedings, American Society for Testing and Materials,
ASTEA Vol 41, 1941, p. 779. Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
A 343–97
Determine the Precision of a Test Method sinusoidal flux waveform by using negative feedback of the
E1338 Guide for the Identification of Metals andAlloys In induced secondary voltage. In this case, higher primary resis-
Computerized Material Property Databases tance can be tolerated since this system will maintain sinusoi-
dal flux at much higher primary resistance. Although the
3. Significance and Use
current drain in the secondary is quite small, especially when
3.1 Thistestmethodisafundamentalmethodforevaluating using modern high-input impedance instrumentation, the
the magnetic performance of flat-rolled magnetic materials in switches and wiring should be selected to minimize the lead
either as-sheared or stress-relief annealed condition. resistance so that the voltage available at the terminals of the
3.2 This test method is suitable for design, specification instruments is imperceptibly lower than the voltage at the
acceptance, service evaluation, and research and development. secondary terminals of the Epstein test frame.
6. Apparatus
4. Test Specimens
6.1 The apparatus shall consist of as many of the following
4.1 The specimens for this test shall be selected and
component parts as are required to perform the desired
prepared for testing in accordance with provisions of Practice
measurement functions:
A34 and as directed in Appendix of this test method.
6.2 Epstein Test Frame:
5. Basic Circuit
6.2.1 The test frame shall consist of four solenoids (each
having two windings) surrounding the four sides of the square
5.1 Fig. 1 shows the essential apparatus and basic circuit
magnetic circuit, and a mutual inductor to compensate for air
connections for this test method. Terminals 1 and 2 are
flux within the solenoids. The solenoids shall be wound on
connected to a source of adjustable ac voltage of sinusoidal
nonmagnetic, nonconducting forms of rectangular cross sec-
wave form and sufficient power rating to energize the primary
tionappropriatetothespecimenmasstobeused.Thesolenoids
circuit without appreciable voltage drop in the source imped-
shall be mounted so as to be accurately in the same horizontal
ance. All primary circuit switches and all primary wiring
plane,andwiththecenterlineofsolenoidsonoppositesidesof
should be capable of carrying much higher currents than are
the square, 250 6 0.3 mm apart. The compensating mutual
normally encountered to limit primary circuit resistance to
inductor may be located in the center of the space enclosed by
values that will not cause appreciable distortion of the flux
the four solenoids if the axis of the inductor is made to be
waveform in the specimen when relatively nonsinusoidal
perpendicular to the plane of the solenoid windings.
currents are drawn. The ac source may be an electronic
6.2.2 The inner or potential winding on each solenoid shall
amplifier which has a sine-wave oscillator connected to its
consist of one fourth of the total number of secondary turns
input and may include the necessary circuitry to maintain a
evenlywoundinonelayeroverawindinglengthof191mmor
longer of each solenoid. The potential windings of the four
solenoids shall be connected in series so their voltages will
Annual Book of ASTM Standards, Vol 14.01.
FIG. 1 Basic Circuit for Wattmeter-Ammeter-Voltmeter Method
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
A 343–97
add.Theouterormagnetizingwindinglikewiseshallconsistof used, an analog flux voltmeter should have a minimum input
one fourth of the total number of primary turns evenly wound resistance of 5000 V/V of full-scale indication.
over the winding length of each solenoid. These individual
6.4 RMS Voltmeter, V —A true rms-indicating voltmeter
rms
solenoid windings, too, shall be connected in series so their
shall be provided for evaluating the form factor of the voltage
magnetizing forces will add. The primary winding may com-
induced in the secondary winding of the test fixture and for
prise up to three layers using two or more wires in parallel.
evaluating the instrument losses. The accuracy of the rms
6.2.3 Primary and secondary turns shall be wound in the voltmeter shall be the same as that specified for the flux
same direction, with the starting end of each winding being at voltmeter. Either digital or analog rms voltmeters are permit-
the same corner junction of one of the four solenoids. This ted.The normally high-input impedance of digital rms voltme-
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
V/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
unityand,atinductionsfarabovethekneeofthemagnetization
6.2.5 The mutual inductance of the air-flux compensating
curve,approacheszero.Thewattmetermustmaintainadequate
inductor shall be adjusted to be the same as that between the
accuracy (1.0% of reading) even at the most severe (lowest)
test-frame windings to within one turn of the compensator
power factor that is presented to it. Variable scaling devices
secondary. Its windings shall be connected in series with the
maybeusedtocausethewattmetertoindicatedirectlyinunits
corresponding test-frame windings so that the voltage induced
of specific core loss if the combination of basic instrument and
inthesecondarywindingoftheinductorbytheprimarycurrent
scaling devices conforms to the specifications stated here.
will completely oppose or cancel the total voltage induced in
the secondary winding of the test frame when no sample is in
6.5.1 Electronic Digital Wattmeter—Electronicdigitalwatt-
place in the solenoids. Specifications for the approximate turns
meters have been developed that have proven satisfactory for
and construction details of the compensating mutual inductor
use under the provisions of this test method. Usage of a
for the standard test frame are given in Table A1.1 of Annex
suitable electronic digital wattmeter is permitted as an alterna-
A1.
tive to an electrodynamometer wattmeter in this test method.
6.3 Flux Voltmeter, V—A full-wave true-average, voltme- An electronic digital wattmeter oftentimes is preferred in this
f
test method because of its digital readout and its capability for
ter, with scale reading in average volts times 2 p/4 so that
=
its indications will be identical with those of a true rms direct interfacing with electronic data acquisition systems.
voltmeter on a pure sinusoidal voltage, shall be provided for
6.5.1.1 The voltage input circuitry of the electronic digital
evaluating the peak value of the test induction. To produce the
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%. Also the voltage input
or analog flux voltmeters are permitted. The normally high-
circuitry must be capable of accepting the maximum peak
input impedance of digital flux voltmeters is desirable to
voltagethatisinducedinthesecondarywindingduringtesting.
minimize loading effects and to reduce the magnitude of
6.5.1.2 The current input circuitry of the electronic digital
instrument loss compensations. The input resistance of an
wattmeter must have an input impedance of no more than 1 V.
analog flux voltmeter shall not be less than 1000 V/V of
Preferably the input impedance should be no more than 0.1 V
full-scale indication. A resistive voltage divider, a standard-
ifthefluxwaveformdistortionotherwisetendstobeexcessive.
ratio transformer, or other variable scaling device may be used
Also the current input circuitry must be capable of accepting
to cause the flux voltmeter to indicate directly in units of
the maximum rms current and the maximum peak current
induction if the combination of basic instrument and scaling
drawnbytheprimarywindingofthetestfixturewhencoreloss
device conforms to the specifications stated above.
tests are being performed. In particular, since the primary
current will be very nonsinusoidal (peaked) if core-loss tests
NOTE 1—Inaccuracies in setting the test voltage produce errors ap-
are performed on a specimen at inductions above the knee of
proximately two times as large in the specific core loss. Voltage scales
should be such that the instrument is not used at less than half scale. Care the magnetization curve, the crest factor capability of the
should also be taken to avoid errors caused by temperature and frequency
current input circuitry should be three or more.
effects in the instrument.
6.5.2 Electrodynamometer Wattmeter—A reflecting-type
6.3.1 If used with a mutual inductor as a peak ammeter at dynamometer is recommended among this class of instru-
inductions well above the knee of the magnetization curve, the ments, but, if the specimen mass is sufficiently large, a
flux voltmeter must be capable of accurately measuring the direct-indicating electrodynamometer wattmeter of the highest
extremelynonsinusoidal(peaked)voltagethatisinducedinthe availablesensitivityandlowestpower-factorcapabilitymaybe
secondary
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