ASTM A 912 : 1993 : R1998

1.1 This test method covers tests for various magnetic properties of amorphous materials at power frequencies (25 to 400 Hz) using a toroidal test transformer. The term toroidal test transformer is used to describe the test device reserving the term specimen to refer to the material used in the test. The test specimen consists of toroidally wound flat strip.

1.2 This test method covers the determination of coreloss, exciting power, rms and peak exciting current, several types of ac permeability, and related properties under ac magnetization at moderate and high inductions at power frequencies (25-70 Hz).

1.3 With proper instrumentation and specimen preparation, this test method is acceptable for measurements at frequencies from 5 Hz to 100 kHz. Proper instrumentation implies that all test instruments have the required frequency band-width. Also see Annex A2.

1.4 This test method also provides procedures for calculating impedance permeability from measured values of rms exciting current and for calculating ac peak permeability from measured peak values of total exciting current at magnetizing forces up to about 10 Oe (796 A/m).

1.5 Explanation of symbols and brief definitions appear in the text of this test method. The official symbols and definitions are listed in Terminology A340.

1.6 This test method shall be used in conjunction with Practice A34.

1.7 This standard does not purport to address all of the safety problems, 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.