Investigation on partial discharge of power cable termination defects using High Frequency Current Transformer

This paper presents partial discharge (PD) investigation of different cable termination defects. The medium voltage power cables as rated of 3.6/7 (7.2) kV are applied. The partial discharges pattern of each case is detected by using a commercial High Frequency Current Transformer (HFCT). The simple cases for internal, surface and corona discharge are firstly observed in order to investigate the performance of the HFCT. Then eight different cases studies of cable termination defects are further investigated, which includes non-terminator, voids between XLPE and stress control, 20 mm. overlaps between semiconductor and stress control, particles on XLPE, non-smooth XLPE, needle tip on insulation screen, impropriate cable bending, and proper termination. The results are then compared with the results from a conventional PD diagnosis tool according to IEC 60270 standard. The results of PD detection show that the commercial product can detect the PD waveform and measure the electric charge when it is highly enough. The test can also identify trends toward breakdown and there severity due to improper cable termination defects.