ASTM A927/A927M-04

This test method is a derivative of Test Method A 697/A 697M specifically designed for testing of toroidal cores which are not covered in Test Method A 697/A 697M and for testing at magnetic flux densities above the knee of the magnetization curve.

Specimen size typically ranges from 1 to 1.25 in. [25.4 to 31.8 mm] in inside diameter to 1.5 in. [38.1 mm] in outside diameter with weights ranging from 30 to 60 g. Provided the test equipment is suitably chosen, there is no obvious limit to the overall size of core that can be tested. If basic material properties are desired, then the requirements of 5.1 must be observed.

The reproducibility and repeatability of this test method are such that this test method is suitable for design, specification acceptance, service evaluation, and research and development.

When testing under sinusoidal flux conditions at magnetic flux densities approaching saturation, highly peaked magnetizing waveforms will be present, and the test instruments used must have crest factor capabilities of at least 3; otherwise erroneous results will be obtained.

1.1 This test method covers the determination of several ac magnetic properties of either laminated ring or toroidal tape wound cores made from flat rolled product.

1.2 This test method covers test equipment and procedures for determination of specific core loss, specific exciting power, and peak permeability for power and audio frequencies (50 to 20 000 Hz) under sinusoidal flux conditions.

1.3 This test method, because of the use of a feedback-controlled power amplifier, is well suited for determination of ac magnetic properties at magnetic flux densities above the knee of the magnetization curve and is particularly useful for testing of high-saturation iron-cobalt alloys (for example, alloys listed in Specification A 801), although use of this test method is not restricted to a particular type of material.

1.4 This test method shall be used in conjunction with Practice A 34/A 34M and Terminology A 340.

1.5 The values and equations stated in customary (cgs-emu and inch-pound) or SI units are to be regarded separately as standard. Within this standard, SI units are shown in brackets except for the sections concerning calculations where there are separate sections for the respective unit systems. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with this standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.