Polymeric Insulator Defect Detection and Analysis Method Based on Microwave Signal

Polymeric insulator is key to safe operation of the whole power transmission system. With the purpose of realizing accurate detection of defects in polymeric insulation core rod, a multiangular microwave diagnostic system for defects detection is proposed. The microwave detection system is based on the wave impedance theory and utilizes the difference of S (scattering) parameters to distinguish defects. First, simulation investigation is presented regarding the millimeter-scale defects of different sizes. The Frobenius norm difference between the defective mandrel and the intact mandrel can be observed visibly in the high frequency range. Then, an experimental setup is designed and manufactured to verify the simulations. The measurement results display significant Frobenius norm difference between the defective mandrel and the intact mandrel over 2.5–6 GHz. Finally, the proposed method is employed to distinguish several types of defects with different physical properties in terms of permeability and dielectric constant. The nondestructive microwave diagnostic method is based on multiangular transmission signal and can reliably identify the defects of millimeter scale by the introduction of Frobenius norm analysis. It is promising for the detection of defects in polymeric insulators as well as other nonconstructive materials.