In this paper, the authors discuss the mechanism of ultrasound generated by partial discharge. When the discharge occurs, charged particles and neutral particles will collide. In the process of collision, interactions between charged and neutral particles in the ionized gas lead to a perturbation of the surrounding air, and thus generate ultrasound. In the case of void in cable insulation, repeated partial discharge is one of the main sources of insulation degradation, which may lead to complete insulation breakdown. Therefore, it is important to monitor the condition of cable insulation through partial discharge measurement. In order to study the propagation law and attenuation characteristics of ultrasound generated by partial discharges, a cable simulation model is established. This cable model is armored with optical fiber to monitor partial discharge. The results show that the attenuation of ultrasound from XLPE insulation layer to the fiber core is 58dB-64dB.

Discharge mechanism; Propagation characteristics; Ultrasound