Eddy current sensors uses the principle of
eddy current formation to sense displacement. These sensors measure shaft displacement in rotating machinery and have been around for many years as they offer manufacturers high-linearity, high-speed measurements, and high resolution.
Eddy currents are formed when a moving or changing
magnetic field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
intersects a conductor or vice versa. The relative motion causes a circulating flow of electrons, or currents, within the conductor. These circulating eddies of current create
electromagnets
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in t ...
with magnet fields that oppose the effect of applied magnetic field. The stronger the applied magnetic field, or greater the electrical conductivity of the conductor, or greater the relative velocity of motion, the greater the currents developed and greater the opposing field. Eddy current probes senses this formation of secondary fields to find out the distance between the probe and target material.
References
Position sensors
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