Yu. Ya. Reutov

MAGNETIC NOISES OF MICROCHIP-TYPE HALL TRANSDUCERS

There is a need to use Hall microchip transducers in non-destructive eddy current testing instead of induction coils, traditionally used to convert the parameters of an alternating magnetic field into an electric signal. The advantage of microchip sensors, along with their manufacturability and low cost, is the low dependence of their efficiency on the frequency of the perceived alternating field (especially in the low-frequency region). At low operating frequencies, the signal voltage induced in the receiving coils of an eddy current flaw detector becomes comparable with the intrinsic noise of its receiving path, and to isolate this signal reliably, it is necessary to increase the number of turns of the receiving coil, which is not always acceptable due to strict requirements for its dimensions. This advantage of Hall transducers (sensors) opens up prospects for a significant expansion of the scope of application of non-destructive eddy current testing. An obstacle to this could be the relatively high intrinsic noise of such sensors, observed at zero operating frequencies and amounting to several (and sometimes dozens of) microteslas (in units of magnetic induction).

This paper presents the results of measuring the noise characteristics of promising 1SA-1M microchip-type Hall magnetic field sensors manufactured by Sentron. It has been found that, at frequencies from 20 Hz to 10 kHz, the intrinsic noises of the examined sensors are tens of times less than those observed at zero frequency. Their amplitude does not exceed tenths of a microtesla (in units of the induction of the measured alternating magnetic field), and this opens up possibilities for using these sensors in eddy current flaw detectors with low (tens of hertz) operating frequencies instead of induction coils. This can expand the application of non-destructive eddy current testing. The obtained information can also be useful in developing means for measuring alternating magnetic fields, regardless of eddy current flaw detection.

Acknowledgment: The study was performed under the state assignment from the Russian Ministry of Science and Higher Education, theme Diagnostics, No. 122021000030-1.

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