1、Designation: A804/A804M 04 (Reapproved 2015)Standard Test Methods forAlternating-Current Magnetic Properties of Materials atPower Frequencies Using Sheet-Type Test Specimens1This standard is issued under the fixed designation A804/A804M; the number immediately following the designation indicates the
2、 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 These test methods cover the determination of speci
3、ficcore loss and peak permeability of single layers of sheet-typespecimens tested with normal excitation at a frequency of 50 or60 Hz.NOTE 1These test methods have been applied only at the commercialpower frequencies, 50 and 60 Hz, but with proper instrumentation andapplication of the principles of
4、testing and calibration embodied in the testmethods, they are believed to be adaptable to testing at frequenciesranging from 25 to 400 Hz.1.2 These test methods use calibration procedures thatprovide correlation with the 25-cm 250-mm Epstein test.1.3 The range of test magnetic flux densities is gove
5、rned bythe properties of the test specimen and by the availableinstruments and other equipment components. Normally, non-oriented electrical steels can be tested over a range from 8 to 16kG 0.8 to 1.6 T for core loss. For oriented electrical steels, thenormal range extends to 18 kG 1.8 T. Maximum ma
6、gneticflux densities in peak permeability testing are limited princi-pally by heating of the magnetizing winding and tests arelimited normally to a maximum ac magnetic field strength ofabout 150 Oe 12 000 A/m.1.4 These test methods cover two alternative procedures asfollows:Test Method 1Sections 612
7、Test Method 2Sections 13191.4.1 Test Method 1 uses a test fixture having (1) twowindings that encircle the test specimen, and (2) a ferromag-netic yoke structure that serves as the flux return path and haslow core loss and low magnetic reluctance.1.4.2 Test Method 2 uses a test fixture having (1) tw
8、owindings that encircle the test specimen, (2) a third windinglocated inside the other two windings and immediately adja-cent to one surface of the test specimen, and (3) a ferromag-netic yoke structure which serves as the flux-return path andhas low magnetic reluctance.1.5 The values and equations
9、stated in customary (cgs-emuand inch-pound) units or SI units are to be regarded separatelyas standard. Within this standard, SI units are shown inbrackets except for the sections concerning calculations wherethere are separate sections for the respective unit systems. Thevalues stated in each syste
10、m may not be exact equivalents;therefore, each system shall be used independently of the other.Combining values from the two systems may result in noncon-formance with this standard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theres
11、ponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A34/A34M Practice for Sampling and Procurement Testingof Magnetic MaterialsA340 Terminolog
12、y of Symbols and Definitions Relating toMagnetic TestingA343/A343M Test Method for Alternating-Current Mag-netic Properties of Materials at Power Frequencies UsingWattmeter-Ammeter-Voltmeter Method and 25-cm Ep-stein Test FrameA677 Specification for Nonoriented Electrical Steel FullyProcessed TypesA
13、683 Specification for Nonoriented Electrical Steel, Semi-processed TypesA876 Specification for Flat-Rolled, Grain-Oriented, Silicon-Iron, Electrical Steel, Fully Processed Types3. Terminology3.1 Definitions:1These test methods are under the jurisdiction of ASTM Committee A06 onMagnetic Properties an
14、d are the direct responsibility of Subcommittee A06.01 onTest Methods.Current edition approved Oct. 1, 2015. Published October 2015. Originallyapproved in 1982. Last previous edition approved in 2009 as A804/A804M04(2009)1. DOI: 10.1520/A0804_A0804M-04R15.2For referenced ASTM standards, visit the AS
15、TM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Unite
16、d States13.1.1 GeneralThe definitions of terms, symbols, and con-version factors relating to magnetic testing found in Terminol-ogy A340 are used in these test methods.3.2 Definitions of Terms Specific to This Standard:3.2.1 sheet specimena rectangular specimen comprised ofa single piece of material
17、 or paralleled multiple strips ofmaterial arranged in a single layer.4. Significance and Use4.1 Materials EvaluationThese test methods were devel-oped to supplement the testing of Epstein specimens forapplications involving the use of flat, sheared laminationswhere the testing of Epstein specimens i
18、n either the as-shearedor stress-relief-annealed condition fails to provide the mostsatisfactory method of predicting magnetic performance in theapplication.As a principal example, the test methods have beenfound particularly applicable to the control and evaluation ofthe magnetic properties of ther
19、mally flattened, grain-orientedelectrical steel (Condition F5, Specification A876) used aslamination stock for cores of power transformers. Inasmuch asthe test methods can only be reliably used to determineunidirectional magnetic properties, the test methods havelimited applicability to the testing
20、of fully processed nonori-ented electrical steels as normally practiced (SpecificationA677).4.2 Specification AcceptanceThe reproducibility of testresults and the accuracy relative to the 25-cm 250-mmEpstein method of test are considered such as to render the testmethods suitable for materials speci
21、fication testing.4.3 Interpretation of Test ResultsBecause of specimensize, considerable variation in magnetic properties may bepresent within a single specimen or between specimens thatmay be combined for testing purposes. Also, variations mayexist in test values that are combined to represent a te
22、st lot ofmaterial. Test results reported will therefore, in general, repre-sent averages of magnetic quality and in certain applications,particularly those involving narrow widths of laminations,deviations in magnetic performance from those expected fromreported data may occur at times. Additionally
23、, application oftest data to the design or evaluation of a particular magneticdevice must recognize the influence of magnetic circuitry uponperformance and the possible deterioration in magnetic prop-erties arising from construction of the device.4.4 Recommended Standard TestsThese test methods have
24、been principally applied to the magnetic testing of thermallyflattened, grain-oriented electrical steels at 50 and 60 Hz.Specific core loss at 15 or 17 kG 1.5 or 1.7 T and peakpermeability (if required) at 10 Oe 796 A/m are the recom-mended parameters for evaluating this class of material.5. Samplin
25、g5.1 Lot Size and SamplingUnless otherwise established bymutual agreement between the manufacturer and the purchaser,determination of a lot size and the sampling of a lot to obtainsheets for specimen preparation shall follow the recommenda-tions of Practice A34/A34M, Sections 5 and 6.METHOD 1 TWO-WI
26、NDING YOKE-FIXTURE TESTMETHOD6. Basic Test Circuit6.1 Fig. 1 provides a schematic circuit diagram for the testmethod.Apower source of precisely controllable ac sinusoidalvoltage is used to energize the primary circuit. To minimizeflux-waveform distortion, current ratings of the power sourceand of th
27、e wiring and switches in the primary circuit shall besuch as to provide very low impedance relative to the imped-ance arising from the test fixture and test specimen. Ratings ofswitches and wiring in the secondary circuit also shall be suchas to cause negligible voltage drop between the terminals of
28、 thesecondary test winding and the terminals of the measuringinstruments.7. Apparatus7.1 The test circuit shall incorporate as many of the follow-ing components as are required to perform the desired mea-surements.7.2 Yoke Test FixtureFig. 2 and Fig. 3 show line drawingsof a single-yoke fixture and
29、a double-yoke fixture, respectively.FIG. 1 Basic Circuit Diagram for Method 1A804/A804M 04 (2015)2A double-yoke fixture is preferred in this method but asingle-yoke fixture is permitted. Directions concerning thedesign, construction, and calibration of the fixture are given in7.2.1, 7.2.2, Annex A1,
30、 and Annex A2.7.2.1 Yoke StructureVarious dimensions and fabricationprocedures in construction are permissible. Since the recom-mended calibration procedure provides correlation with the25-cm 250-mm Epstein test, the minimum inside dimensionbetween pole faces must be at least 22 cm 220 mm. Thethickn
31、ess of the pole faces should be not less than 2.5 cm 25mm. It is recognized that pole faces as narrow as 1.9 cm 19mm are being used with nickel-iron yoke systems with goodresults. To minimize the influences of coil-end and pole-faceeffects, the yokes should be longer than the recommendedminimum. For
32、 calibration purposes, it is suggested that thewidth of the fixture be such as to accommodate a specimen ofat least 36-cm 360-mm width which corresponds to thecombined width of twelve Epstein-type specimens. Should thefixture width be less than 36 cm 360 mm, it will be necessaryto test each calibrat
33、ion specimen in two parts and average theresults.7.2.2 Test WindingsThe test windings, which shall consistof a primary (exciting) winding and a secondary (potential)winding, shall be uniformly and closely wound on anonmagnetic, nonconducting coil form and each shall span thegreatest practicable dist
34、ance between the pole faces of the yokefixture. It is recommended that the number of turns in theprimary and secondary windings be equal. The number of turnsmay be chosen to suit the instrumentation, mass of specimenand test frequency. The secondary winding shall be theinnermost winding and, with in
35、strumentation of suitably highinput resistance, normally may consist of a single layer. Toreduce self-impedance and thereby minimize flux-waveformdistortion, it is recommended that the primary winding consistof multiple layers of equal turns connected in parallel. Thenumber of such layers should be
36、optimized based on consid-eration of a reduction in winding resistance versus an increasein inductive reactance at the third harmonic of the principal testfrequency used. The primary and secondary turns shall bewound in the same direction from a common starting point atone end of the coil form.Also,
37、 to minimize self-impedances ofthe windings, the opening in the coil form should be no greaterthan required to allow easy insertion of the test specimen.Construction and mounting of the test coil assembly must besuch that the test specimen will be maintained without me-chanical distortion in the pla
38、ne established by the pole faces ofthe yoke(s) of the test fixture.7.3 Air-Flux CompensatorTo provide a means of deter-mining intrinsic induction in the test specimen, an air-coremutual inductor shall constitute part of the test-coil system.The respective primary and secondary windings of the air-co
39、reinductor and the test-specimen coil shall be connected in seriesand the voltage polarities of the secondary windings shall be inopposition. By proper adjustment of the mutual inductance ofthe air-core inductor, the average of the voltage developedacross the combined secondary windings is proportio
40、nal to theintrinsic induction in the test specimen. Directions for con-struction and adjustment of the air-core mutual inductor forair-flux compensation are found in Annex A3.7.4 Flux Voltmeter, VfAfull-wave, true-average voltmeter,with scale reading in average voltage times 1.111 so that itsindicat
41、ions will be identical with those of a true rms voltmeteron a pure sinusoidal voltage, shall be provided for evaluatingthe peak value of the test magnetic flux density. To produce theestimated precision of test under this method, the full-scalemeter errors shall not exceed 0.25 % (Note 2). Meters of
42、 0.5 %or more error may be used at reduced accuracy. Either digitalor analog flux voltmeters are permitted. The normally highinput impedance of digital voltmeters is desirable to minimizeloading effects and to reduce the magnitude of instrument losscompensations. The input resistance of an analog fl
43、ux voltme-ter shall not be less than 1000 /V of full-scale indication. Aresistive voltage divider, a standard-ratio transformer, or othervariable scaling device may be used to cause the flux voltmeterto indicate directly in units of magnetic flux density if thecombination of basic instrument and sca
44、ling device conformsto the specifications stated above.NOTE 2Inaccuracies in setting the test voltage produce percentageerrors approximately two times as large in the specific core loss. Careshould also be taken to avoid errors caused by temperature and frequencyeffects in the instrument.7.4.1 If us
45、ed 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 the mutual inductor.FIG. 2 Single-Y
46、oke Fixture (Exploded View)FIG. 3 Double-Yoke Fixture (Exploded View)A804/A804M 04 (2015)3Additionally, if so used, an analog flux voltmeter should havean input resistance of 5000 to 10 000 /V of full-scaleindication.7.5 RMS Voltmeter, VrmsA true rms-indicating voltmetershall be provided for evaluat
47、ing 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 high input
48、impedance of digital voltmeters isdesirable to minimize loading effects and to reduce the mag-nitude of instrument loss compensations. The input resistanceof an analog rms voltmeter shall not be less than 500 /V offull-scale indication.7.6 Wattmeter, WThe full-scale accuracy of the wattmetermust be
49、better than 60.25 % 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 wattmeter mustmaintain adequate accuracy (better than 61 % of reading) evenat the most severe (lowest) power factor that is presented to it.Variable scaling devices may be used to cause the wattmeter toindicate directly in units of specific core loss if the co
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