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In principle, LET represents a modification of the traditional eddy current testing from which it differs in two aspects, namely (i) how eddy currents are induced and (ii) how their perturbation is detected. In LET eddy currents are generated by providing the relative motion between the conductor under test and a permanent magnet(see figure).
In electromagnetism, an eddy current (also called Foucault's current) is a loop of electric current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction or by the relative motion of a conductor in a magnetic field. Eddy currents flow in closed loops within conductors, in planes ...
There was a hard, universally used pass-fail criterion for the Eddy Test, and a second chance was normally never allowed. Eddy described the test as having questions with multiple-choice answers, with each of the answers giving some indication of the test-taker's mathematics/physics knowledge, creativity, reasoning ability, and general aptitude.
If the test is set up properly, a defect inside the test object creates a measurable response. The term "electromagnetic testing" is often intended to mean simply eddy-current testing (ECT). However, with an expanding number of electromagnetic and magnetic test methods, "electromagnetic testing" is more often used to mean the whole class of ...
Although RFT works in nonferromagnetic materials such as copper and brass, its sister technology eddy-current testing is preferred. The basic RFT probe consists of an exciter coil (also known as a transmit or send coil) which sends a signal to the detector (or receive coil). The exciter coil is pumped with an AC current and emits a magnetic field.
These are called eddy currents. On the lefthand side nearest to the other wire (1) the eddy current is in the opposite direction to the main current (big pink arrow) in the wire, so it subtracts from the main current, reducing it. On the righthand side (2) the eddy current is in the same direction as the main current so it adds to it ...
Second, there is the question of whether eddy currents occur in a superconductor. Our article starts out by saying "Eddy currents (also called Foucault currents) are electric currents induced within conductors by a changing magnetic field in the conductor." An obvious corollary is this: no magnetic field = no induction = no eddy current.
Eddy current sensors are displacement sensors that use 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. [ 1 ]