AC BARKHAUSEN NOISE IN ELECTRICAL STEELS: INFLUENCE OF SENSING TECHNIQUE ON INTERPRETATION OF MEASUREMENTS

Anthony J. Moses – Harshad V. Patel – Paul I. Williams

   Barkhausen noise is an important magnetic phenomenon in applications as diverse as magnetic recording and non-destructive testing. Although discovered almost 90 years ago, the origin and characteristics of Barkhausen noise is still not fully understood. Its sensitivity to changes in the microstructure and stress state of a material can be difficult to measure and interpret. This paper briefly reviews the development of Barkhausen noise measurement techniques up to the present time. Two measurement techniques are presented as examples of measuring Barkhausen noise in electrical steel at typical power frequencies. The first method uses an enwrapping flux sensing double-coil to detect Barkhausen jumps and the second technique uses an inductive ferrite core surface probe. Statistical methods have been applied in analysing the Barkhausen noise signal under various experimental conditions. The effect of changing the separation distance between detection coils on the measurement of Barkhausen noise is used as an example to highlight how the detection method can influence the interpretation of the Barkhausen signal.

Keywords: Barkhausen Noise, Electrical Steel, Pick-up coil, Surface Probe, RMS Analysis

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