Researchers and engineers are constantly developing novel techniques to accurately measure the electromagnetic properties of electrical insulators. These properties provide useful information about the insulators' performance and aging degree, which may help users to take necessary actions to prevent potential risks to the safety and stability of electric power systems. In this study, terahertz (THz) time-domain spectroscopy (THz-TDS) is used to analyze the spectral absorption and dielectric dispersion of five electrical insulation materials viz. epoxy resin (PER), E-glass fiber-reinforced polymer-matrix composite (GFRP), cross-linked polyethylene (XLPE), electrical porcelain (E-PRL), and high temperature vulcanized silicone rubber (HTVSR), in the THz frequency range (0.1 THz-1.8 THz). The refractive index, absorption coefficient, and complex relative permittivity of each sample are experimentally measured using the THz-TDS system and theoretically calculated using the original Debye model (i.e., based on the relaxation process of the individual samples’ dipoles). Experimental and theoretical results of the refractive indices and dielectric constants of the individual samples are highly correlated with 0.22% and 0.17% aggregate maximum errors, respectively. The values of dielectric constants and imaginary permittivities are found to be the highest and the lowest for E-PRL and XLPE, respectively. In terms of dielectric performance, XLPE exhibits the highest and most stable dielectric performance, followed by the E-PRL, whereas PER, HTVSR, and GFRP exhibit fluctuating and slightly less stable dielectric performance. This study shows the great potential of THz nondestructive testing (NDT) and structural health monitoring (SHM) for the defect detection and service life prediction of electrical insulators.

研究人员和工程师不断开发新技术来准确测量电绝缘体的电磁特性。这些特性提供了有关绝缘子性能和老化程度的有用信息，可以帮助用户采取必要的措施，防止对电力系统安全和稳定性的潜在风险。在本研究中，太赫兹 (THz) 时域光谱 (THz-TDS) 用于分析五种电绝缘材料的光谱吸收和介电色散，即. 环氧树脂（PER）、无碱玻璃纤维增​​强聚合物基复合材料（GFRP）、交联聚乙烯（XLPE）、电瓷（E-PRL）和高温硫化硅橡胶（HTVSR），太赫兹频率范围（0.1 THz-1.8 THz）。每个样品的折射率、吸收系数和复相对介电常数均使用 THz-TDS 系统进行实验测量，并使用原始德拜模型进行理论计算（即.，基于单个样品偶极子的弛豫过程）。单个样品的折射率和介电常数的实验和理论结果分别与 0.22% 和 0.17% 的聚合最大误差高度相关。发现 E-PRL 和 XLPE 的介电常数和虚介电常数值分别最高和最低。在介电性能方面，XLPE 的介电性能最高且最稳定，其次是 E-PRL，而 PER、HTVSR 和 GFRP 的介电性能波动且稳定性稍差。本研究显示了太赫兹无损检测 (NDT) 和结构健康监测 (SHM) 在电绝缘体缺陷检测和使用寿命预测方面的巨大潜力。