ASTM A598/A598M-02(2007)

The method of excitation simulates, to a practical degree, the operation of a magnetic core in a self-saturating magnetic amplifier. The properties measured are related to the quality of performance of the cores in magnetic amplifiers and are useful for the specification of materials for such cores.

1.1 This test method covers the determination of the magnetic performance of fully processed cores for magnetic amplifier-type applications.

1.2 Tests may be conducted at excitation frequencies of 60, 400, 1600 Hz, or higher frequencies.

1.3 Permissible core sizes for this test method are limited only by the available power supplies and the range and sensitivity of the instrumentation.

1.4 At specified values of full-wave sinusoidal-current excitation, H_max, this test method provides procedures of determining the corresponding value of maximum induction, B_max.

1.5 At specified values of half-wave sinusoidal-current excitation, this test method provides procedures for determining the residual induction, B_r.

1.6 At increased specified values of half-wave sinusoidal-current excitation, this test method provides procedures for determining the dc reverse biasing magnetic field strength, H₁, required to reset the induction in the core material past B_r to a value where the total induction change, ΔB₁, becomes approximately one third of the induction change, 2 B_p. It also provides procedures for determining the additional dc reset magnetic field strength, ΔH, which, combined with H₁, is the value required to reset the induction in the core material past B_r to a value where the total induction change, ΔB₂, becomes approximately two thirds of the induction change 2 B_p.

1.7 This test method specifies procedures for determining core gain from the corresponding biasing and induction changes, ΔH and ΔB.

1.8 This test method covers test procedures and requirements for evaluation of finished cores which are to be used in magnetic-amplifier-type applications. It is not a test for basic-material magnetic properties.

1.9 This test method shall be used in conjunction with Practice A 34/A 34.

1.10 Explanations of symbols and abbreviated definitions appear in the text of this test method. The official symbols and definitions are listed in Terminology A 340.

1.11 The values and equations stated in customary (cgs-emu and inch-pound) or SI units are to be regarded separately as standard. Within this test method, SI units are shown in brackets. 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 test method.

1.12 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.