1、Designation: A 343/A 343M 03 (Reapproved 2008)Standard Test Method forAlternating-Current Magnetic Properties of Materials atPower Frequencies Using Wattmeter-Ammeter-VoltmeterMethod and 25-cm Epstein Test Frame1This standard is issued under the fixed designationA 343/A 343M; the number immediately
2、following the designation indicates the yearof 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. Scope1.1 This test me
3、thod covers tests for the magnetic propertiesof basic flat-rolled magnetic materials at power frequencies (25to 400 Hz) using a 25-cm Epstein test frame and the 25-cmdouble-lap-jointed core. It covers the determination of coreloss, rms exciting power, rms and peak exciting current, andseveral types
4、of ac permeability and related properties offlat-rolled magnetic materials under ac magnetization.1.2 This test method shall be used in conjunction withPractice A 34/A 34M.1.3 This test method2provides a test for core loss andexciting current at moderate and high magnetic flux densitiesup to 15 kG 1
5、.5 T on nonoriented electrical steels and up to18 kG 1.8 T on grain-oriented electrical steels.1.4 The frequency range of this test method is normally thatof the commercial power frequencies 50 to 60 Hz. With properinstrumentation, it is also acceptable for measurements at otherfrequencies from 25 t
6、o 400 Hz.1.5 This test method also provides procedures for calculat-ing ac impedance permeability from measured values of rmsexciting current and for ac peak permeability from measuredpeak values of total exciting currents at magnetic fieldstrengths up to about 150 Oe 12 000 A/m.1.6 Explanation of s
7、ymbols and abbreviated definitionsappear in the text of this test method. The official symbols anddefinitions are listed in Terminology A 340.1.7 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equiva
8、lents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard. Within this standard, SI units are shown inbrackets except in the sections concerning calculations wherethere are separate sections for the resp
9、ective unit systems.1.8 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to
10、 use.2. Referenced Documents2.1 ASTM Standards:3A 34/A 34M Practice for Sampling and Procurement Test-ing of Magnetic MaterialsA 340 Terminology of Symbols and Definitions Relating toMagnetic TestingA 677 Specification for Nonoriented Electrical Steel FullyProcessed TypesA 683 Specification for Nono
11、riented Electrical Steel, Semi-processed TypesA 876 Specification for Flat-Rolled, Grain-Oriented,Silicon-Iron, Electrical Steel, Fully Processed TypesA 889/A 889M Test Method for Alternating-Current Mag-netic Properties of Materials at Low Magnetic Flux Den-sity Using the Voltmeter-Ammeter-Wattmete
12、r-VarmeterMethod and 25-cm Epstein FrameE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 1338 Guide for Identification of Metals and Alloys inComputerized Material Property Dat
13、abases3. Significance and Use3.1 This test method is a fundamental method for evaluatingthe magnetic performance of flat-rolled magnetic materials ineither as-sheared or stress-relief annealed condition.1This test method is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is th
14、e direct responsibility of SubcommitteeA06.01 on TestMethods.Current edition approved May 1, 2008. Published June 2008. Originallyapproved in 1949. Last previous edition approved in 2003 as A 343/A 343M-03.2Burgwin, S. L., “Measurement of Core Loss and A-C Permeability with the25-cm Epstein Frame,”
15、Proceedings, American Society for Testing and Materials,ASTEA, Vol 41, 1941, p. 779.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary p
16、age onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2 This test method is suitable for design, specificationacceptance, service evaluation, and research and development.4. Test Specimens4.1 The specimens for this
17、 test shall be selected andprepared for testing in accordance with provisions of PracticeA 34/A 34M and as directed in Appendix of this test method.5. Basic Circuit5.1 Fig. 1 shows the essential apparatus and basic circuitconnections for this test method. Terminals 1 and 2 areconnected to a source o
18、f adjustable ac voltage of sinusoidalwaveform and sufficient power rating to energize the primarycircuit without appreciable voltage drop in the source imped-ance. All primary circuit switches and all primary wiringshould be capable of carrying much higher currents than arenormally encountered to li
19、mit primary circuit resistance tovalues that will not cause appreciable distortion of the fluxwaveform in the specimen when relatively nonsinusoidalcurrents are drawn. The ac source may be an electronicamplifier which has a sine-wave oscillator connected to itsinput and may include the necessary cir
20、cuitry to maintain asinusoidal flux waveform by using negative feedback of theinduced secondary voltage. In this case, higher primary resis-tance can be tolerated since this system will maintain sinusoi-dal flux at much higher primary resistance. Although thecurrent drain in the secondary is quite s
21、mall, especially whenusing modern high-input impedance instrumentation, theswitches and wiring should be selected to minimize the leadresistance so that the voltage available at the terminals of theinstruments is imperceptibly lower than the voltage at thesecondary terminals of the Epstein test fram
22、e.6. Apparatus6.1 The apparatus shall consist of as many of the followingcomponent parts as are required to perform the desiredmeasurement functions:6.2 Epstein Test Frame:6.2.1 The test frame shall consist of four solenoids (eachhaving two windings) surrounding the four sides of the squaremagnetic
23、circuit, and a mutual inductor to compensate for airflux within the solenoids. The solenoids shall be wound onnonmagnetic, nonconducting forms of rectangular cross sec-tion appropriate to the specimen mass to be used.The solenoidsshall be mounted so as to be accurately in the same horizontalplane, a
24、nd with the center line of solenoids on opposite sides ofthe square, 250 6 0.3 mm apart. The compensating mutualinductor may be located in the center of the space enclosed bythe four solenoids if the axis of the inductor is made to beperpendicular to the plane of the solenoid windings.6.2.2 The inne
25、r or potential winding on each solenoid shallconsist of one fourth of the total number of secondary turnsevenly wound in one layer over a winding length of 191 mm orlonger of each solenoid. The potential windings of the foursolenoids shall be connected in series so their voltages willadd. The outer
26、or magnetizing winding likewise shall consist ofone fourth of the total number of primary turns evenly woundover the winding length of each solenoid. These individualsolenoid windings, too, shall be connected in series so theirmagnetic field strengths will add. The primary winding maycomprise up to
27、three layers using two or more wires in parallel.6.2.3 Primary and secondary turns shall be wound in thesame direction, with the starting end of each winding being atthe same corner junction of one of the four solenoids. Thisenables the potential between adjacent primary and secondaryFIG. 1 Basic Ci
28、rcuit for Wattmeter-Ammeter-Voltmeter MethodA 343/A 343M 03 (2008)2turns to be a minimum throughout the length of the winding,thereby reducing errors as a result of electrostatic phenomena.6.2.4 The solenoid windings on the test frame may be anynumber of turns suited to the instrumentation, mass of
29、speci-men, and test frequency. Windings with a total of 700 turns arerecommended for tests in the frequency range of 25 through400 Hz.6.2.5 The mutual inductance of the air-flux compensatinginductor shall be adjusted to be the same as that between thetest-frame windings to within one turn of the com
30、pensatorsecondary. Its windings shall be connected in series with thecorresponding test-frame windings so that the voltage inducedin the secondary winding of the inductor by the primary currentwill completely oppose or cancel the total voltage induced inthe secondary winding of the test frame when n
31、o sample is inplace in the solenoids. Specifications for the approximate turnsand construction details of the compensating mutual inductorfor the standard test frame are given in Table A1.1 of AnnexA1.6.3 Flux Voltmeter, VfA full-wave true-average, voltme-ter, with scale reading in average volts tim
32、es=2 p/4 so thatits indications will be identical with those of a true rmsvoltmeter on a pure sinusoidal voltage, shall be provided forevaluating the peak value of the test magnetic flux density. Toproduce the estimated precision of test under this test method,the full-scale meter errors shall not e
33、xceed 0.25 % (Note 1).Meters of 0.5 % of more error may be used at reducedaccuracy. Either digital or analog flux voltmeters are permitted.The normally high-input impedance of digital flux voltmetersis desirable to minimize loading effects and to reduce themagnitude of instrument loss compensations.
34、 The input resis-tance of an analog flux voltmeter shall not be less than 1000V/V of full-scale indication. A resistive voltage divider, astandard-ratio transformer, or other variable scaling devicemay be used to cause the flux voltmeter to indicate directly inunits of magnetic flux density if the c
35、ombination of basicinstrument and scaling device conforms to the specificationsstated above.NOTE 1Inaccuracies in setting the test voltage produce errors ap-proximately two times as large in the specific core loss. Voltage scalesshould be such that the instrument is not used at less than half scale.
36、 Careshould also be taken to avoid errors caused by temperature and frequencyeffects in the instrument.6.3.1 If used with a mutual inductor as a peak ammeter atmagnetic flux densities well above the knee of the magnetiza-tion curve, the flux voltmeter must be capable of accuratelymeasuring the extre
37、mely nonsinusoidal (peaked) voltage that isinduced in the secondary winding of the mutual inductor.Additionally, if so used, an analog flux voltmeter should havea minimum input resistance of 5000 V/V of full-scale indica-tion.6.4 RMS Voltmeter, VrmsA true rms-indicating voltmetershall be provided fo
38、r evaluating the form factor of the voltageinduced in the secondary winding of the test fixture and forevaluating the instrument losses. The accuracy of the rmsvoltmeter shall be the same as that specified for the fluxvoltmeter. Either digital or analog rms voltmeters are permit-ted. The normally hi
39、gh-input impedance of digital rms voltme-ters is desirable to minimize loading effects and to reduce themagnitude of instrument loss compensations. The input resis-tance of an analog rms voltmeter shall not be less than 5000V/V of full-scale indication.6.5 Wattmeter, WThe full-scale accuracy of the
40、wattmetermust not be poorer than 0.25 % at the frequency of test and atunity power factor. The power factor encountered by a watt-meter during a core loss test on a specimen is always less thanunity and, at magnetic flux densities far above the knee of themagnetization curve, approaches zero. The wa
41、ttmeter mustmaintain adequate accuracy (1.0 % of reading) even at the mostsevere (lowest) power factor that is presented to it. Variablescaling devices may be used to cause the wattmeter to indicatedirectly in units of specific core loss if the combination of basicinstrument and scaling devices conf
42、orms to the specificationsstated here.6.5.1 Electronic Digital WattmeterElectronic digital watt-meters have been developed that have proven satisfactory foruse under the provisions of this test method. Usage of asuitable electronic digital wattmeter is permitted as an alterna-tive to an electrodynam
43、ometer wattmeter in this test method.An electronic digital wattmeter oftentimes is preferred in thistest method because of its digital readout and its capability fordirect interfacing with electronic data acquisition systems.6.5.1.1 The voltage input circuitry of the electronic digitalwattmeter must
44、 have an input impedance sufficiently high thatconnection of the circuitry, during testing, to the secondarywinding of the test fixture does not change the terminal voltageof the secondary by more than 0.05 %. In addition, the voltageinput circuitry must be capable of accepting the maximum peakvolta
45、ge that is induced in the secondary winding during testing.6.5.1.2 The current input circuitry of the electronic digitalwattmeter must have an input impedance of no more than 1 V.Preferably the input impedance should be no more than 0.1 Vif the flux waveform distortion otherwise tends to be excessiv
46、e.In addition, the current input circuitry must be capable ofaccepting the maximum rms current and the maximum peakcurrent drawn by the primary winding of the test fixture whencore loss tests are being performed. In particular, since theprimary current will be very nonsinusoidal (peaked) if core-los
47、s tests are performed on a specimen at magnetic fluxdensities above the knee of the magnetization curve, the crestfactor capability of the current input circuitry should be threeor more.6.5.2 Electrodynamometer WattmeterA reflecting-typedynamometer is recommended among this class of instru-ments, bu
48、t, if the specimen mass is sufficiently large, adirect-indicating electrodynamometer wattmeter of the highestavailable sensitivity and lowest power-factor capability may beused.6.5.2.1 The sensitivity of the electrodynamometer wattme-ter must be such that the connection of the potential circuit ofth
49、e wattmeter, during testing, to the secondary winding of thetest fixture does not change the terminal voltage of thesecondary by more than 0.05 %. Also, the resistance of thepotential circuit of the wattmeter must be sufficiently high thatthe inductive reactance of the potential coil of the wattmeter incombination with the leakage reactance of the secondaryA 343/A 343M 03 (2008)3circuit of the test fixture does not result in appreciable defectangle errors in the measurements. Should the impedance of thiscombined reactance at the test frequency exceed 1.0 V per1000 V of r
