Electrical breakdown strength of 5 kV imperfect XLPE cable after combined AC-DC excitation

Electrical breakdown strength of 5 kV imperfect XLPE cable under different combined AC-DC excitation is studied. Two types of imperfect cable samples were used in this research: cable samples with artificial holes inside the insulation and cable samples with embedded metal needles. A comparison of the breakdown voltage under pulsating excitation for imperfect and sound cable shows that the pulsating excitation can be used to detect the imperfections inside XLPE cable. The effect of the pulsating voltage excitation on the degradation and remaining breakdown voltage of the tested cable is studied. The remaining breakdown voltage of the tested cable is evaluated with AC excitation