Bubble dynamics and channel formation for cathode initiated discharges in transformer oil

M. Cevallos, M. Butcher, J. Dickens, A. Neuber, H. Krompholz

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

6 Scopus citations


The development of cathode initiated low density channel formation and propagation leading to self breakdown in transformer oil is investigated using high speed electrical and optical diagnostics in a coaxial system with a point/plane axial discharge at various hydrostatic pressures. A cathode initiated channel formation and propagation model based upon single bubble dynamics has been presented by Kattan [1]. Experiments based on high-speed shadowgraphy were conducted to decide if the principles that govern single bubble dynamics could be applied to cathode initiated channel formation. These experiments show bubble motion away from the cathode, with separation velocities on the order of 10's m/s. This separation is similar for single bubbles generated at the cathode and for bubble chains developing into low-density channels. Lifetimes of these channels are recorded and show good correlation with the Rayleigh model [2] used to predict lifetimes of single bubbles. Experiments at reduced hydrostatic pressure reveal a critical pressure below which low density channel expansion occurs, further corroborating the presence of a gas phase. Finally, the pressure dependence of the breakdown voltage due to the expansion of the low density channels is examined and a model for this dependence is presented. The experiments conducted confirm the presence of a gas phase channel, its correlation with single bubble dynamics, and its importance to final breakdown.

Original languageEnglish
Title of host publication2005 IEEE Pulsed Power Conference, PPC
Number of pages4
StatePublished - 2007
Event2005 IEEE Pulsed Power Conference, PPC - Monterey, CA, United States
Duration: Jun 13 2005Jun 17 2005

Publication series

NameDigest of Technical Papers-IEEE International Pulsed Power Conference


Conference2005 IEEE Pulsed Power Conference, PPC
Country/TerritoryUnited States
CityMonterey, CA


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