Precision and Accuracy Study on Measurement of Soft Magnetic Properties Using DC Hysteresigraphs

摘要

DC hysteresigraphs are the predominant method of measurement of the technologically important dc magnetic properties of soft magnetic materials. The relative ease of use, compatibility with computerization and apparent ease of obtaining a large quantity of data has resulted in this technique largely replacing traditional ballistic measurements. The use of dc hysteresigraphs is covered by ASTM Test Method A 773 [1]. To the authors' knowledge, the precision and accuracy of dc hysteresigraphs has not been published in the technical literature, nor has it ever been formally established by interlaboratory study. Consequently, an interlaboratory study was initiated under the auspices of ASTM Committee A06 on Magnetic Properties. Test specimens were circulated among the participants, who used a variety of commercially produced or custom-built test units to perform the required measurements. Upon completion of the interlaboratory testing, the test specimens were measured at the National Physical Laboratory in England to establish the reference values for a statement of accuracy (NIST does not offer a similar capability in the United States). This paper presents the results of this study and indicates some areas of concern about the commercial equipment used for these measurements.