Partial discharge characteristics of voids in extruded insulations-theoretical studies

Theoretical studies of partial discharge (PD) characteristics of voids in extruded high voltage insulation were made. Important physical quantities such as discharge inception stress (DIS), electric stress inside the insulation (E_d), which corresponds to the DIS, theoretical PD magnitude (Q), as well as the probability of free electron appearance were calculated. The calculations were made for spherical voids of different diameters. The results were compared with currently valid standards and test requirements for extruded high voltage cables. Suggestions concerning PD measurements and tests are made