Breakdown Characteristics of a Transformer Oil in Moderately-Uniform Fields under Lightning Impulse

Haichuan Yu, Qiang Liu, Zhongdong Wang, Mark Wilkinson, Christoph Krause, Attila Gyore, Andree Hilker

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


This paper presents an experimental study on the breakdown characteristics of a mineral transformer oil in moderately-uniform fields under standard lightning impulse. To achieve the moderately-uniform fields with the field factors from 5.5 to 31.3, the rod to plane electrode geometry was applied with the rod tip radius of 0.5 mm and gap distances from 3 mm to 25 mm. The negative breakdown voltages raise up steeply against the gap distance when the gap distance is lower than 10 mm and for higher gap distance the increasing rate of the breakdown voltage is reduced. Based on the simulated maximum electric field under the breakdown voltage, the negative transition field factor boundary between streamer initiation dominated breakdown and streamer propagation dominated breakdown is deduced at 9.6 which experimentally verifies the previous extrapolation based estimation. The positive breakdown voltages were also measured under the same conditions, which indicated that all the breakdowns are dominated by the streamer initiation in such moderately-uniform fields. This also evidences that the transition field factor boundary is polarity dependent and negative lightning impulse shows a lower transition field factor boundary value compared to the positive one.
Original languageEnglish
Title of host publication2022 IEEE 21st International Conference on Dielectric Liquids, ICDL 2022
Subtitle of host publicationSevilla, Spain May 29 – June 2, 2022
Place of PublicationNew York
PublisherIEEE Computer Society
Number of pages4
ISBN (Electronic)9781665484916
ISBN (Print)9781665484916
Publication statusPublished - 2022

Publication series

NameProceedings - IEEE International Conference on Dielectric Liquids
ISSN (Print)2153-3725
ISSN (Electronic)2153-3733


  • breakdown
  • lightning impulse
  • mineral oil
  • moderately-uniform field
  • transformer


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