The Propagation of Partial Discharge Pulses in a High Voltage Cable

Partial discharge within the dielectric of HV solid dielectric power cable greatly shortens the cable life. It is desirable to detect and locate the PD in the cable before breakdown occurs. Understanding the phenomena of propagation of the PD pulse in a power cable is fundamental to the detection and location of PDs. In this paper a power cable model represented by a coaxial transmission lossless line was analyzed theoretically. Based on this model PD pulse propagation in a power cable was simulated by using EMTP ( Electro-Magnetic Transients Program ). A capacitive sensor has also been developed with a high frequency response to detect PD propagation. Pulse transmission properties of PDs were measured on a short length of 22 kV XLPE cable in the laboratory . The experimental results show a good agreement with the theoretical analysis. The paper describes the test results and the theoretical modelling performed. It also discusses the pulse attenuation in time and frequency domain and discusses this with reference to practical PD detection in the field.