Magnet Mounted accelerometer near Eddy current probes.

Dear Experts,

A question just clicked my mind that can there be a disturbance in eddy current probe output, if a magnet mount sensor is placed near it during portable data collection(Casing Vibrations)?


Original Post

There would be minimal effect on a proximity probe from a sensor magnet in close proximity.  For one thing it would be a static non-varying magnetic field.

If we further look at the case of a varying magnetic field, thus a field able to create a voltage given the presence of a conductor in that field, then the chart below shows the effect of a 300 Gauss 60 Hz field on a proximity probe mounted on a generator.  It shows that for 5-meter proximitor, probe and cable at a 50 mil gap, the total effect (mil pp/Gauss) to be 0.0159 mil/Gauss (0.0131 + 0.0014 + 0.0014).  At 300 Gauss that would be 4.8 mils.  That may seem like a lot but it isn't because generators rarely have fields above a few Gauss outside the generator frame.  Think many years ago, and even today, if fields were high you would remove any mechanical watch (yep, still made; think Rolex, Omega, etc.) while working on these machines. 

If you are interested in seeing various devices and what they might exhibit in magnetic fields, go to 





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