Eddy Current Array Inspection
Eddy Current Array Technology
Eddy current array (ECA) technology provides the ability to electronically drive and read several eddy current sensors positioned side by side in the same probe assembly. Data acquisition is made possible through the use of multiplexing, which avoids mutual inductance between individual coils.
The OmniScan® ECA test configuration supports 32 sensor coils (up to 64 with an external multiplexer) working in bridge or transmit-receive mode. The operating frequency ranges from 20 Hz to 6 MHz with the option of using multiple frequencies in the same acquisition.
Benefits of Eddy Current Arrays
Compared to single-channel eddy current technology, eddy current array technology provides the following benefits:
- Dramatically reduces inspection time.
- Covers a large area in a single pass.
- Reduces the complexity of mechanical and robotic scanning systems.
- Provides real-time cartography of the inspected region, facilitating data interpretation.
- Is well suited to complex part geometry.
- Improves reliability and probability of detection (POD).
Eddy Current Array Probes
Olympus manufactures ECA probes for a wide range of applications. Probes can be designed to detect a specific type of flaw or to follow the shape of the part being inspected. Standard designs are available to detect defects such as cracks and pitting, and subsurface defects such as cracks in multilayer structures, as well as corrosion.
Multiplexing principle between elements. Coils are shown for illustration purposes only.
Eddy current array probes can replace one axis of a two-axis scan and offer greater flexibility in the eddy current setup.
Probes can be made in different shapes and sizes to follow, with ease, the contour of the part under inspection.
Transmit-receive probe for corrosion detection down to 6 mm (0.25 in.) in aluminum
Transmit-receive probe for surface-crack detection shown with optional encoder
Absolute probe for surface crack detection
Eddy Current Array Software
Simple Acquisition and Analysis Displays
- Data acquisition in a C-scan view for quick and efficient defect detection
- Data selection in Analysis mode to review the signal in the impedance plane and strip charts
- Amplitude, phase, and position measurement
- Adjustable color palette
- Large impedance plane and strip chart views to accommodate conventional single-channel ECT probe inspection
Calibration Wizard
- Step-by-step process
- All the channels of a group are calibrated simultaneously, each channel having its own gain and rotation.
- Amplitude and phase can be set on different reference flaws.
Alarms
- Three alarm outputs can combine LED, buzzer, and TTL output.
- Various alarm zone shapes can be defined in the impedance plane (sectorial, rectangular, ring, etc.).
Automatic Probe Detection and Configuration
- C-scan parameters and multiplexing sequence are automatically set when the probe is connected.
- Frequency range protection to avoid probe damage
Subtraction Tools in Analysis Mode
This function can be used to remove the lift-off variation that is shown between adjacent channels.
Advanced Real-Time Data Processing
- Real-time data interpolation to improve the spatial representation of defects
- When working with two frequencies, a MIX signal can be generated to remove unwanted signals (for example, lift-off, fastener signals, etc.).
- Several filters can be applied to the data such as high-pass, low-pass, median, and averaging filters. The illustrations below represent an application where cracks are located at the edge of a lap-joint which has a sharp thickness variation. The filtered data may improve detection, especially for small cracks.
