An eddy current is a well known reaction in electromagnetism. They exist in the ferromagnetic core of various static and moving electromagnetic induction based machines, for example, transformers and motors.
Is it possible to directly measure eddy currents?
Thanks Dr. Huseyin for recommending the mentioned method. It is the most simple indirect method of quantifying the resultant effects of eddy currents based on indirect measurements. The problem is that some of the secondary components of the consequent magnetic fields within the material may cancel each other partially or totally. Therefore, their resultant field becames weaker than thier real heating system internal effects. The presented method measures the results consequence, but these consequences may not reflect the real effects of the eddy currents. Another method widely used in measuring the equivalent parameters of power transformers; the open circuit test transform the measured voltage and current to an equivalent circuit that includes the power loss and phase shift effects. On the other hand, the equivalent temperature rise of the I2R losses seems to be less than the real change in the temperature. Therefore, I am searching for a more accurate method for estimating the heating effects of eddy currents. This problem is outside my research scope, but it challenges me when overheating symptoms shown in a home appliance.
Direct measuring of eddy currents is simply impractical. Yes, you can attach electrodes to the media, where you excite currents, and measure the current directly. This will be called a transformer.
Measuring eddy currents is a special area of NDT. NDT, nondestructive, in most cases means non-interfering with the media, or often just non-contact, or indirect.
So, probably your question is reduced to high-resolution methods of measuring eddy currents, where you avoid cancelling of mid-range magnetic field, by observing current flow microstructure.
A lot of patents were written, and secrets are hidden by companies. So no one can help you. I can just give a hint: if you examine flat surfaces in direct proximity, you can use magneto-optics (faraday, kerr-effect) to image excitation. But the application of the method is difficult because of really very close proximity.
P.S. AFAIK, most magneto-optic crystals are temperature-sensitive. So your heating effect will interfere.
Thanks Dr. Preston for your valuable feedback. I agree with you that the costs of measuring such complex phenomenon should be compensated by their return and outcome. It is really a complex task to precisely measure these currents, but I am sure that large industries found a feasible way for considering that relatively important issue.
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