Standard Test Methods for Alternating-Current Magnetic Properties of Materials at Power Frequencies Using Sheet-Type Test Specimens

Importancia y uso:

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 Interpretation 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. Also, variations may exist in test values that are combined to represent a test lot of material. Test results reported will therefore, in general, represent averages of magnetic quality and in certain applications, particularly those involving narrow widths of laminations, deviations in magnetic performance from those expected from reported data may occur at times. Additionally, application of test data to the design or evaluation of a particular magnetic device must recognize the influence of magnetic circuitry upon performance and the possible deterioration in magnetic properties arising from construction of the device.

4.4 Recommended Standard Tests—These test methods have been principally applied to the magnetic testing of thermally flattened, grain-oriented electrical steels at 50 and 60 Hz. Specific core loss at 15 or 17 kG [1.5 or 1.7 T] and peak permeability (if required) at 10 Oe [796 A/m] are the recommended parameters for evaluating this class of material.

Subcomité:

A06.01

Referida por:

A0876-17E01, A1036-04R20, A0345-19

Volúmen:

03.07

Número ICS:

77.140.40 (Steels with special magnetic properties)

Palabras clave:

alternating current; ammeter; core loss; magnetic; magnetic flux density; magnetic material; magnetic test; permeability; power frequency; sheet; voltmeter; wattmeter;