Distribution Network Cable Detection Based on Terahertz Pulse and Imaging

Moisture of high voltage distribution network cables will cause major safety hazard, but there is no effective means to detect and analyze the internal humidity state of the cables. Therefore, it is urgent to develop a new nondestructive detection method to evaluate the waterproof performance of distribution network cables and their connectors. The internal structure of the cable is a multilayer structure composed of wires, cross-linked polyethylene insulation layer, and silicone rubber insulation sheath. We used the reflective terahertz pulse signal to detect the internal states of the cable, and judge whether it contains water stains according to the echo characteristics. In addition, three-dimensional data was obtained through cylindrical coordinate scanning and terahertz images were reconstructed based on feature information, which were consistent with the distribution of water stains between the cable insulation sheath and cross-linked polyethylene insulation layer. The results show that the terahertz technology can realize the high sensitivity detection of cable moisture state, which is of great significance in the power and transmission industry.