Relationship between Development of Electrical Tree and Frequency Components of Electromagnetic Waves Associated with Partial Discharge

Defects such as voids in a solid insulator can cause partial discharges that lead to accidents or breakdown. Our group has been investigating a diagnosing method that detects electromagnetic waves associated with partial discharges occurring in a solid insulator. In our previous work, our method successfully identified the partial discharge of epoxy-insulated power equipment in the field. The proposed method can determine whether the point of partial discharge occurrence is inside or outside of the solid insulator by detecting electromagnetic waves. In addition, degradation of the solid insulator can be diagnosed from the frequency characteristics of the radiated electromagnetic waves. However, a clear theoretical understanding of the cause of these characteristics has remained elusive.…