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In the traditional version of eddy current testing an alternating (AC) magnetic field is used to induce eddy currents inside the material to be investigated. If the material contains a crack or flaw which make the spatial distribution of the electrical conductivity nonuniform, the path of the eddy currents is perturbed and the impedance of the ...
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 ...
Eddy currents flow in closed loops in planes perpendicular to the magnetic field. They have useful applications in eddy current brakes and induction heating systems. However eddy currents induced in the metal magnetic cores of transformers and AC motors and generators are undesirable since they dissipate energy (called core losses) as heat in ...
Cause of skin effect. A main current I flowing through a conductor induces a magnetic field H.If the current increases, as in this figure, the resulting increase in H induces separate, circulating eddy currents I W which partially cancel the current flow in the center and reinforce it near the skin.
An eddy current separator (ECS) is a machine that uses a powerful magnetic field to separate non-ferrous metals from an input waste or ore stream. The device makes use of eddy currents to effect the separation. Non-ferrous metals typically separated by an ECS include aluminum, copper and die-cast metals. [1]
The current in the sample is detected by a current coil wound around a section of the toroid (a current transformer). This method is good for measuring the setting properties of concrete, its hydration and strength. Wet concrete has a resistivity of around 1 Ω-m which progressively increases as the cement sets. [3]
Jumping rings lift when an AC current energises a coil and the electrodynamic forces pushes the rings upwards against gravity. Electrodynamic suspension (EDS) is a form of magnetic levitation in which there are conductors which are exposed to time-varying magnetic fields.
Diagram of a coil inducing an eddy current in a conductive plate. The relative motion causes a circulating flow of electrons, or currents, within the conductor. These circulating eddies of current create electromagnets with magnet fields that oppose the effect of applied magnetic field. The stronger the applied magnetic field, or greater the ...