Defects detection and localization of short cables with DAC method

Localization XLPE cable defects with damped AC (DAC) voltage technique is suitable for medium-length cable (1000m~3000m), however, the precision decreases when the cable is shorter than 500m. For it is hard to distinguish the incident and reflected pulses in time using time domain reflectometry (TDR) with high oscillating frequency. To solve the problem, a compensation capacitor in parallel and optimization of detect unit and amplifier are proposed. This paper presents a laboratory experiment on 10kV XLPE short cables (<;500m) with four artificial typical defects. The results of defects detection and PD mapping are satisfactory, which prove the feasibility and effectiveness of damped AC voltage method to detect and locate the insulation defects of short cables.