Eddy Current Testing in Wind Turbines
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Source: Wind Powered Engineering
Eddy current technology has long been used in nondestructive testing (NDT) for wind turbine tower welds, drivetrains and a wide range of spot inspections in O&M programs. Itís a fast, accurate, chemical-free method for detecting surface and sub-surface indications that are too small to see with the naked eye, including cracks, pits, corrosion and damage due to impact or fatigue.

Eddy current testing has the added benefit of producing an electronic inspection record for advanced analysis and reporting, a big advantage over dye penetrant testing (PT) and magnetic particle testing (MT).

Unlike PT or MT, eddy current results are digital and can be analyzed, saved, shared, stored and compared at any time. Eddy current can also "see" through non-conductive coatings like paint without technicians having to pretreat the surface ó a time-consuming and messy process.

Eddy current testing involves using a portable instrument and a probe with a coil that fires electronic currents into the material. Eddy current array (ECA) probes have multiple coils that fire at coordinated times and can capture more information in a single pass, transforming the eddy current inspection from a process that might last several minutes per joint to one that takes seconds.

One practical limitation of eddy current technology is that the coils in the probe need to be close to the material for accurate flaw detection and signal quality. Itís a challenge because of the various component geometries, weld shapes, rough surfaces and hard-to-reach areas on a wind turbine.

Read the full article at WindTurbineEngineering.com.