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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-current testing (ECT) is used to detect near-surface cracks and corrosion in metallic objects such as tubes and aircraft fuselage and structures. ECT is more commonly applied to nonferromagnetic materials, since in ferromagnetic materials the depth of penetration is relatively small.
To determine if metal loss is occurring on the internal or external surface of a pipe, a separate eddy current sensor is utilized to indicate wall surface location of the anomaly. The unit of measure when sensing an MFL signal is the gauss or the tesla and generally speaking, the larger the change in the detected magnetic field, the larger the ...
less sensitive to probe wobble than conventional eddy current testing (its sister technology for nonferromagnetic materials) because the field travels on the outside of the pipe, RFT shows reduced accuracy and sensitivity at conductive and magnetic objects on or near the outside of the pipe, such as attachments or tube support plates.
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.