Li Luming and Zhang Jiajun NDT Lab. Mechanical Department, Tsinghua University Beijing P. R. China
Keywords: Hall probe, pulse current, magnetic flux leakage testing (MFL), sensitivity, signal processing
ABSTRACT
Hall probe is the most common used sensor in magnetic flux leakage testing. Generally, the exciting current of Hall probe is direct or alternating current. In this paper, periodical pulse current is used as the exciting source in order to increase the Hall probe's sensitivity by raising the amplitude of the pulse current. For the same magnetic field strength, the output of Hall probe will increase more than 15 dB comparing with the direct current. The principle of this method and the signal processing are all introduced. The experimental data show that the relationship when the exciting current is direct. The theoretical explanation is given. The change of Hall probe output linearity is concerned too. At last, the testing result of 0.1 mm depth surface crack with direct current and pulse current are compared.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.Vol. 3, pages 1597 - 1600 Publisher:Ashgate Publishing Company
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