Composite shadowgraphy and luminosity images of self breakdown discharge channels in transformer oil

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

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


The physics of cathode initiated discharge formation 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. Previous research conducted on self breakdown channel formation using high speed shadowgraphy and photography of the emitted light has shown tree-like structures for both cathode and anode initiated discharges, with characteristic differences. Cathode initiated discharges expand faster to a more "bushy" appearance, whereas anode initiated discharges show branching localized channels. So far, the spatial resolution to detect small luminous areas in pre-breakdown discharges and to determine their correlation to low density regions visible in the shadowgraphs was not sufficient in the experiments described in this paper, thus a systematic variation of exposure times, and time delays between luminosity pictures and shadowgraphy pictures has been performed. These experiments confirm that the luminosity emitted during prebreakdown events is generated from the low density regions seen in the shadowgraphy images, indicating charge amplification mechanisms in the gas phase for cathode initiated events. This statement is further supported by the dependence of both the channel dynamics and the light emission at lowered hydrostatic pressure.

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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