Temporal and spatial development of partial discharges in spherical voids in epoxy related to the detected electrical signal.

Investigations were made on the temporal and spatial development of partial discharges (PD) in spherical voids (/spl oslash/: 1 -5 mm) in clear epoxy plastic. Two very different types of discharges were found with respect to charge image, luminosity and propagation time. The electrical signal simultaneously displayed on a 1 GHz real-time oscilloscope, showing pulses with rise times in the ns and sub-ns range of varying magnitude and shape. Pulse phase/height analyses were performed showing a uniques pattern for all voids. A relationship was established between the shape of the detected pulses, pulse phase/height analyses and optical characteristics of the discharge phenomena.