Discharges in combined transformer oil/paper insulation

Discharge signatures and breakdown levels have been recorded for combined transformer oil/impregnated paper insulation subjected to AC high voltage. Different electrode geometries have been studied, varying from the point-plane gap to a semi-homogeneous sphere-plane configuration. At high moisture levels discharge activity was monitored at an average electric field below 1 kV/mm, with breakdown occurring 6 kV/mm. Characteristic discharge patterns were identified for corona, wedge, void and creeping discharges, but depend strongly on applied voltage, time and moisture content of the insulation.

[1]  O. Lesaint,et al.  Streamer generation and propagation in transformer oil under divergent field conditions , 1987, 1987 Ninth International Conference on Conduction and Breakdown in Dielectric Liquids.

[2]  L. Lundgaard,et al.  Evaluation of dielectric liquids by measurement of their partial discharge characteristics , 1994, Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP'94).

[3]  L. Lundgaard,et al.  Discharges in liquids in point-plane gap under ac and impulse stress , 1995, Proceedings of 1995 Conference on Electrical Insulation and Dielectric Phenomena.

[4]  L. Lundgaard,et al.  Streamers from a metallic particle between parallel plane electrodes in transformer oil , 1999, Proceedings of 1999 IEEE 13th International Conference on Dielectric Liquids (ICDL'99) (Cat. No.99CH36213).