ASTM A804/A804M-04 (R2021) pdf free download.Standard Test Methods for Alternating-Current Magnetic Properties of Materials at Power Frequencies Using Sheet-Type Test Specimens.
1 .1 These test methods cover the determination of specific core loss and peak permeability of single layers of sheet-type specimens tested with normal excitation at a frequency of 50 or 60Hz.
1 .2 These test methods use calibration procedures that provide correlation with the 25-cm L250-rnrnj Epstein test.
1.3 The range of test magnetic flux densities is governed by the properties of the test specimen and by the available instruments and other equipment components. Normally, non- oriented electrical steels can be tested over a range from 8 to 16 kG for core loss. For oriented electrical steels, the normal range extends to 18 kG [1.8 Tj. Maximum magnetic flux densities in peak permeability testing are limited principally by heating of the magnetizing winding and tests are limited normally to a maximum ac magnetic field strength of about 150 Oe (12 000 A/mI.
1.4 These test methods cover two alternative procedures as
follows:
Test Method 1—Sections 6 — 12
Test Method 2—Sections 13 — 19
1.4.1 Test Method 1 uses a test fixture having (1) two windings that encircle the test specimen. and (2) a ferromagnetic yoke structure that serves as the flux return path and has low core loss and low magnetic reluctance.
1.4.2 Test Method 2 uses a test fixture having (1) two windings that encircle the test specimen, (2) a third winding located inside the other two windings and immediately adjacent to one surface of the test specimen.
4. Significance and Use
4. 1 Materials Evaluation—These test methods were developed to supplement the testing of Epstein specimens for applications involving the use of flat, sheared laminations where the testing of Epstein specimens in either the as-sheared or stress-relief-annealed condition fails to provide the most satisfactory method of predicting magnetic performance in the application. As a principal example, the test methods have been found particularly applicable to the control and evaluation of the magnetic properties of thermally flattened, grain-oriented electrical steel (Condition F5, Specification A876) used as lamination stock for cores of power transformers. Inasmuch as the test methods can only be reliably used to determine unidirectional magnetic properties, the test methods have limited applicability to the testing of fully processed nonoriented electrical steels as normally practiced (Specification
A677).
4.2 Specification Acceptance—The reproducibility of test results and the accuracy relative to the 25-cm [250-mm] Epstein method of test are considered such as to render the test methods suitable for materials specification testing.
4.3 lizterpretaiion of Test Results—Because of specimen size, considerable variation in magnetic properties may be
present within a single specimen or between specimens that may be combined for testing purposes.ASTM A804/A804M pdf download.