Electrical breakdown strength of 5 kV cross-linked polyethylene cables under AC, DC, and pulsating voltage

Electrical breakdown strength of the 5 kV Cross-linked Polyethylene (XLPE) cables was studied under ac, dc and pulsating voltages. Two types of imperfections were studied: Cable samples with artificial holes and cable samples with embedded needles. Study results showed that the pulsating voltage may be an effective way to detect the imperfections inside the XLPE cable. A theoretical curve was obtained to predict the pulsating breakdown voltage for XLPE insulation. It fit well with the measured data for the cable with artificial holes, while it fit less for the cable with embedded needles. The effect of the pulsating test aging on the remaining ac breakdown voltage of the XLPE cable was studied. Results showed that the aging due to the pulsating voltage during the test will not affect much the ac breakdown voltage of the XLPE cable.