Eddy Current Array (ECA) is a form of nondestructive eddy current testing that involves electronically driving eddy current coils placed next to each other in a probe assembly. Each coil in the probe produces a signal, the strength of which depends on the phase and amplitude of the object the probe is placed over. This signal can be measured and the data recorded. This data can then be referenced to an encoded position and time and represented visually as a C-scan image.
In general, eddy current inspections are a method of non-destructive testing that use the principle of electromagnetic induction. When alternating current is applied to a conductor, in the case of an eddy current probe, a magnetic field develops around it which changes in intensity as the current alternates. If another conductor, in this case the material being tested, is brought close to the first field, a current will be induced in it as well. If there are any flaws in this material then the eddy current emanating from it will be distorted.
ECA is capable of reproducing the flaw detection techniques of most other eddy current methods. This method though had several distinct advantages such as:
Being able to scan a larger area at one time while maintaining a high resolution,
A lesser need for complex robotics to actually move the probe,
Improved flaw detection due to the C-scan imaging, and
Complex shapes can be inspected using this method because the probes can be customized to the profile of the part being inspected.
This method is widely used for a number of industry applications. It can be used both measuring the thickness of steels and detecting corrosion. ECA can be used on materials as diverse as vessels, columns, storage tanks & spheres, piping systems, and even structural applications.
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