Prediction of Elongation at Break of XLPE Cable Insulation by Near-infrared Spectroscopy

Considering the swift progress of urbanization, numerous power cables have been integrated into the urban distribution network, which required to pay more attention to the inspection of power cables’ quality. However, the current testing methods for power cable insulation present long testing period, which are unable to ensure full coverage sampling. In order to address the problem, in this paper, the application of near-infrared (NIR) spectroscopy as a non-destructive testing technique for predicting the elongation at break of insulation in cross-linked polyethylene (XLPE) cables has been investigated. 28 kinds of power cables with different service time were studied and the NIR spectra were obtained with the preprocess of smoothing, standard normal variable transformation (SNV), and second-order derivation. In addition, random frog (RF) algorithm was employed to select the wavelengths that are closely related to the structures which are responsible to the properties. 10 wavelengths were further selected for the subsequent modeling by partial least squares regression (PLSR) to predict the elongation at break. The great precision is presented in the results which showed only 1.1% error in prediction. The research offers a convenient technique for assessing the elongation capacity of XLPE insulation at the point of fracture without any potential damage.