Attenuation Characteristics of Partial Discharge Ultrasonic Signals in Cable Joints

Cable joints are critical components of power-cable systems. Preventing insulation defects and guaranteeing the safe, reliable operation of joints are therefore essential for maintaining overall system stability. Partial discharge (PD) is an early indicator of insulation deterioration; ultrasonic detection is among the most effective techniques for identifying PD activity. Consequently, a quantitative investigation into the propagation and attenuation of PD-induced ultrasonic waves inside cable joints is necessary to enhance detection sensitivity. Based on the diffusion attenuation of acoustic waves in homogeneous media and the reflection/refraction laws at material interfaces, this study employs a 10 kV cold-shrink cable joint as a representative model. When the PD source is embedded in the cross-linked polyethylene (XLPE) insulation, the ultrasonic signal experiences an attenuation of 55.41 dB before reaching the outer surface of the joint; when the defect is located within the copper conductor, the attenuation increases to 85.78 dB. These results establish a theoretical foundation for improving the sensitivity and reliability of ultrasonic PD detection in cable joints.