No abstract

Partial discharges (PD) analysis is the common technique for detection and identification of dielectric defects. Certain PD characteristics can be an early sign of degradation. For further understanding, combined voltages can enhance the analysis of PD characteristics in some specific cases. This paper presents an experimental study on the PD appearance under repetitive negative half-sine voltage excitation, as such a combination of AC and DC voltage. Adopting the time-resolved PD pattern technique, PD signals originated from dielectric barrier corona discharge (DBCD) source are recorded in time domain by a DL750 Scope Corder. Preliminary filtered results indicated the strong relationship between surface charge accumulation and back discharge, a time delay movement of back discharge can be clearly observed on the pattern during ‘relaxation time period’ with various insulation materials.