ASTM A343 A343M-2003 Standard Test Method for Alternating-Current Magnetic Properties of Materials at Power Frequencies Using Wattmeter-Ammeter-Voltmeter Method and 25-cm Epstein T.pdf

1、Designation: A 343/A 343M 03Standard 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 designation A 343/A 343M; the number immediately following the des

2、ignation 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers test

3、s 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 of ac permeabili

4、ty 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 T on nonorien

5、ted 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 to 400 Hz.1.5 Thi

6、s 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 symbols and abbre

7、viated definitionsappear in the text of this test method. The official symbols anddefinitions are listed in Terminology A 340.1.7 The values and equations stated in either customary(cgs-emu and inch-pound) or SI units are to be regardedseparately as standard. Within this standard, SI units are shown

8、in brackets except in the sections concerning calculationswhere there are separate sections for the respective unitsystems. The values stated in each system may not be exactequivalents; therefore, each system shall be used independentlyof the other. Combining values from the two systems mayresult in

9、 nonconformance with this standard.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 limit

10、ations prior to use.2. Referenced Documents2.1 ASTM Standards:A 34/A 34M Practice for Sampling and Procurement Test-ing of Magnetic Materials3A 340 Terminology of Symbols and Definitions Relating toMagnetic Testing3A 677/A 677M Specification for Nonoriented ElectricalSteel Fully Processed Types3A 68

11、3/A 683M Specification for Nonoriented ElectricalSteel, Semiprocessed Types3A 876/A 876M Specification for Flat-Rolled, Grain-Oriented, Silicon-Iron, Electrical Steel, Fully ProcessedTypes3A 889/A 889M Test Method for Alternating-Current Mag-netic Properties of Materials at Low Inductions Using theW

12、attmeter-Varmeter-Ammeter-Voltmeter Method and25-cm (250-mm) Epstein Frame3E 177 Practice for Use of the Terms Precision and Bias inASTM Test Methods4E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method4E 1338 Guide for the Identification of Metals and Al

13、loys InComputerized Material Property Databases53. 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.3.2 This test method is suitable for design, specificat

14、ionacceptance, service evaluation, and research and development.1This test method is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the direct responsibility of Subcommittee A6.01 on TestMethods.Current edition approved June 10, 2003. Published July 2003. Originallyapprove

15、d in 1949. Last previous edition approved in 1997 as A 343 97.2See Burgwin, S. L., “Measurement of Core Loss and A-C Permeability with the25-cm Epstein Frame,” Proceedings, American Society for Testing and Materials,ASTEA Vol 41, 1941, p. 779.3Annual Book of ASTM Standards, Vol 03.04.4Annual Book of

16、 ASTM Standards, Vol 14.02.5Annual Book of ASTM Standards, Vol 02.051Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Test Specimens4.1 The specimens for this test shall be selected andprepared for testing in accordance with provisi

17、ons 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 of adjustable ac voltage of sinusoidalwaveform and sufficient power rating

18、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 limit primary circuit resistance tovalues that will not cause appreciable di

19、stortion 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 circuitry to maintain asinusoidal flux waveform by using negative feedback of

20、 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 small, especially whenusing modern high-input impedance instrumentation, th

21、eswitches 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 frame.6. Apparatus6.1 The apparatus shall consist of as many of the followingc

22、omponent 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 circuit, and a mutual inductor to compensate for airflux within the soleno

23、ids. 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, and with the center line of solenoids on opposite sides ofthe square, 250

24、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 inner or potential winding on each solenoid shallconsist of one fourth of the

25、 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 or magnetizing winding likewise shall consist ofone fourth of the total n

26、umber 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 three layers using two or more wires in parallel.FIG. 1 Basic Circuit for

27、 Wattmeter-Ammeter-Voltmeter MethodA 343/A 343M 0326.2.3 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 secondaryturns to be a

28、 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 speci-men, and test frequency. Windings with a total of 700 turns arerecommended

29、 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 compensatorsecondary. Its windings shall be connected in series with thecorrespondi

30、ng 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 no sample is inplace in the solenoids. Specifications for the approximate turnsan

31、d 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 times=2 p/4 so thatits indications will be identical with those of a true rmsvoltme

32、ter 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 exceed 0.25 % (Note 1).Meters of 0.5 % of more error may be used at reducedaccura

33、cy. 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. The input resis-tance of an analog flux voltmeter shall not be less than 1000V/

34、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 combination of basicinstrument and scaling device conforms to the specificationss

35、tated 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. Careshould also be taken to avoid errors caused by temperature and frequencyeff

36、ects 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 extremely nonsinusoidal (peaked) voltage that isinduced in the secondary winding of t

37、he 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 for evaluating the form factor of the voltageinduced in the secondary winding of t

38、he 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 high-input impedance of digital rms voltme-ters is desirable to minimize loading e

39、ffects 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 wattmetermust not be poorer than 0.25 % at the frequency of test and atunity pow

40、er 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 wattmeter mustmaintain adequate accuracy (1.0 % of reading) even at the mostsevere

41、 (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 conforms to the specificationsstated here.6.5.1 Electronic Digital WattmeterElectron

42、ic 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 electrodynamometer wattmeter in this test method.An electronic digital wattmeter oftentimes

43、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 have an input impedance sufficiently high thatconnection of the circuitry, duri

44、ng 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 peakvoltage that is induced in the secondary winding during testing.6.5.1.2 The current i

45、nput 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 excessive.In addition, the current input circuitry must be capable ofaccepting the maxim

46、um 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-loss tests are performed on a specimen at magnetic fluxdensities above the knee of

47、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, but, if the specimen mass is sufficiently large, adirect-indicating electrodynamom

48、eter 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 ofthe wattmeter, during testing, to the secondary winding of thetest fixture does no

49、t change the terminal voltage of theA 343/A 343M 033secondary 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 secondarycircuit 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 resistance in the wattmeter-potential circuit, thepotential circuit must be compensated f