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Eddy Current Array

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. The coils are excited in a specific sequence to eliminate interference from mutual inductance (channel multiplexing). Arrays can be made flexible or shaped to any geometry, and software provides graphical displays (2D and 3D C-scans).

The signals generated can then 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.



ECA has several benefits over other methods of NDE, including shorter inspection times and a higher rate of flaw detection. The results returned from an eddy current inspection also tend to be more intuitive to interpret. Additionally, with eddy current array, the inspection is fully recorded and the records can be kept and reviewed at a later date; there is no need for hand drawn sketches of indications.

ECA is able to accurately detect and size the length and depth of longitudinal surface-breaking cracks in carbon steel welds. It can also be used to detect transverse surface-breaking cracks. With ECA testing, spring loaded "fingers" adapt to the weld crown so that the probe can scan the HAZ, toe, and cap of welds in a single pass. It is much faster than magnetic particle testing and liquid penetrant testing, and is up to 10 times faster than other advanced electromagnetic testing techniques. It can measure up to up to 100' of welds per hour. Finally, this method is able to leverage the power of advanced 2D and 3D C-scan imaging capabilities.



ECA testing allows for defect depth sizing up to 3/8" with the use of integrated calibration curves. Because the probe has a built-in encoder, defects can be accurately located and sized.


  • Minimal surface preparation is required

  • Fewer technicians required per inspection

  • ECA testing allows for inspection through coatings



Sharck probes are a special type of eddy current array probe that were developed to detect cracks in carbon steel, which are normally difficult to examine using eddy current. Sharck probes are based on tangential eddy current array technology, where the coils are placed on their sides, parallel to the surface they are being used to examine. Sharck probes have many of the same advantages of traditional eddy current technologies, including their speed and coverage.



Sentinel Integrity Solutions utilizes advanced ECA equipment and technology for our surface examinations.  Currently, we use Eddyfi’s Reddy Surface ECA.  This instrument has the capabilities to perform the simplest examination from the common pencil probe inspections to complex ECA & TECA probe configurations.  The data is displayed in the common XY display for depth sizing, a C-scan display for identifying defects.  Pairing this instrument with off-line data analysis capabilities, Sentinel Integrity Solutions has the capabilities to reduce man power (1-man operation), reduce inspection times, increase inspection efficiency, and reduce downtime.  

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