Non-destructive testing on wind turbines

As the wind power industry grows, periodic NDT inspection of turbines is increasingly important.

Introduce

Environmental concerns have increased interest in a safer, renewable source of wind energy. As the wind turbine industry grows, it becomes increasingly important to monitor the reliability of turbines. Periodic inspection to find defects in turbine structural components before a major accident also ensures that the turbine is operating at maximum efficiency. Wind turbine blades should be given the most scrutiny by inspectors, because vane failure will result in costly repairs and total wind tower decommissioning. Various nondestructive testing methods can be performed on wind turbine blades. These methods include ultrasonic testing and eddy current testing.

Ultrasonic test on wind turbine

Ultrasonic testing is a common method for inspecting wind turbine blades. Ultrasonic testing equipment such as EPOCH 6LT is light in weight and requires no hazardous radioactive sources and is specifically designed for climbing rope approach. Specialized ultrasonic testing methods, such as phased array ultrasound (PAUT), has more test parameters and gives more detailed results than conventional ultrasound testing. In addition, PAUT allows the technician to steer the beam in multiple directions, whereas conventional ultrasonic testing produces only a fixed emitter position.

Flexible test methods are especially important for wind turbines because the geometry of the blades and other turbine parts has irregular surfaces and shapes. In particular, the propellers often use composite materials with a thick layer of material that can make inspection difficult. Possible materials inside a turbine blade include:

  • Glass fiber
  • Plastic
  • Steel
  • Aluminum

Eddy current test on wind turbine

Eddy current (ET) testing is another popular non-destructive testing method for wind turbines. ET can be used to detect surface and near-surface defects. Eddy current testing, like ultrasonic testing, does not require the use of hazardous materials or an uninterruptible power source. ET devices like NORTEC 600 Extremely light and maneuverable, well suited for wind tower testing applications.

For turbines, the specialized method of phase array eddy current (ECA) testing has several advantages over conventional eddy current technology. For example, ECA can scan welds with complex geometries and materials. Eddy current array testing also offers advantages such as:

  • Touch screen interface
  • Intelligent software, support visual images
  • Multi-coil head, for wider coverage

Conclusion

The lightweight, portable characteristics of ultrasonic testing and eddy current testing make them reliable NDT methods for testing wind turbines. Both methods can detect minor flaws more easily than other NDT methods and tools. Specialized inspection methods such as phased array ultrasound and phased array eddy currents can scan for unusual shapes and composite material structures. These testing methods can also be performed relatively quickly. All these advantages mean that wind turbine inspection NDT technicians can deliver quality test results in less time and ensure that the wind turbines are always in safe operation.

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