Parameter Analysis of Pulsed Eddy Current Sensor Using Principal Component Analysis

Abstract

Pulsed eddy curent (PEC) technique provides a means to inspect structures without surface contact. It is particularly useful when the structure's surface is rough or inaccessible, such as insulated pipes in pipeline. Probe parameters of a PEC system, especially the sensing and excitation coil diameters, can significantly affect the PEC system's performance. Thus, detailed analysis of these parameters is paramount in developing a PEC system. Currently, this is accomplished by establishing the trend of features with respect to the analyzed variables, e.g. sample thicknesses. However, prior to extracting these features, a number of configuration parameters have to be determined. For this reason, analyzing PEC performance over a range of coil diameter values is rather time-consuming as both the sensing and excitation coil diameters significantly affect the received signals. Principal component analysis (PCA) is proposed as an alternative to the feature extraction. The work here analyzes the trends contributed by the PCA scores for different values of sensing and excitation coil parameters. Results from both numerical simulations and experiments suggest that the sensitivity of the PEC probe is highly correlated with the excitation coil diameter, while the excitation-sensing coil distance is not significant in determining the sensitivity of the PEC probe. These findings are consistent with those reported in the literature, suggesting the potential of adopting PCA for an automated PEC performance analysis process.

Space–Time Pulsed Eddy Current Array for NDT of Wellbore Casings Based on MIMO Technique

“…Ĩ m,l denotes the transmitting current of the mth transmitter in the lth period mentioned in (17). Ũ n,l represents the induced EMF of the nth receiver in the lth period mentioned in (19), which can be obtained by measurement at different sampling gates. Notably, the power of each array element is limited by parameters such as the wire diameter in the transmitting system.…”

“…[13] and tool shell against downhole pressure [14] significantly affect the borehole PEC testing accuracy of metal pipes [15,16]. To improve the performance of borehole PEC technologies for metal casing or pipe evaluation, a number of studies have been conducted to understand the effect of the probe parameters of a PEC system [17][18][19][20][21][22][23]. The size and shape of the transmitting and receiving coils have been demonstrated to significantly affect the performance of the PEC system [17], and varying the coil height and width can offer improved sensitivity [18].…”

“…The size and shape of the transmitting and receiving coils have been demonstrated to significantly affect the performance of the PEC system [17], and varying the coil height and width can offer improved sensitivity [18]. In addition, the number of turns of the coil is important in determining the strength of the magnetic field generated by the coil [19]. In [20], the influence of the emission current parameters, including the pulse waveform and width, on the response signal was analyzed to improve the resolution of the defect depth of the PEC system.…”

Decoupling the Influence of Wall Thinning and Cladding Thickness Variations in Pulsed Eddy Current Using Principal Component Analysis

“…Data pre-processing is essential prior to PCA, as the diffusion and decay phases of the raw received signals are not derivable in Cartesian domain [16], as seen in Figure 4(a). The raw PEC signals were bi-symmetrically transformed, using…”

“…An attempt at comparing PCA with Fast Fourier Transform (FFT) as a method for signal decomposition has also been carried out, which has revealed the benefits of both methods in different aspects for the inspection of heat-treated bearing rings [14]. PCA has also been used for probe parameter analysis for pipeline inspection [16]. Another example that is close to the work carried out here is the application of PCA to separate the signal effects of tubes degradation with those of ferromagnetic support, as reported by Buck et al [17], owing to the large difference in the "relaxation times" for eddy current diffusion in the tube compared to those of the ferromagnetic support.…”