Question

Define eddy current?

Answer 1

Eddy currents (also called Foucault currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor due to Faraday's law of induction. Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field. They can be induced within nearby stationary conductors by a time-varying magnetic field created by an AC electromagnet or transformer, for example, or by relative motion between a magnet and a nearby conductor. The magnitude of the current in a given loop is proportional to the strength of the magnetic field, the area of the loop, and the rate of change of flux, and inversely proportional to the resistivity of the material.
Eddy Current Principle. The eddy current method is based on the principle of generating circular electrical currents (eddy currents) in a conductive material. This is achieved by the use of a coil connected to an alternating current generator driving an alternating magnetic field (primary field).

uses of eddy current :

Eddy-current testing. Eddy-current testing (also commonly seen as eddy current testing and ECT) is one of many electromagnetic testing methods used in nondestructive testing (NDT) making use of electromagnetic induction to detect and characterize surface and sub-surface flaws in conductive materials.

Disadvantages of Eddy Currents: There is a major heat loss cycling eddy currents cause loss of energy due to friction in the magnetic circuit, especially where the core is saturated. Thus there is the loss of useful electrical energy in the form of heat. There is magnetic flux leakage.