Dielectric breakdown phenomena of conventional and ‘new’ transformer liquids
| Dates: | 12 October 2023 |
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| Times: | 14:30 - 14:30 |
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| What is it: | Seminar |
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| Organiser: | Department of Electrical and Electronic Engineering |
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| Who is it for: | University staff, General public |
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| Speaker: | Professor Qiang Liu |
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Mineral oils, as a conventional insulating liquid option, have been widely used in power transformers for over a century. In the past decades, a variety of ‘new’ transformer liquids including natural and synthetic ester liquids, gas-to-liquid (GTL) oils, biodegradable hydrocarbon liquids have emerged in the market, and they all possess certain improved properties, e.g. biodegradability, fire safety, purity and so on. Knowledge of transformer insulation design has been accumulated mainly based on the experience of using mineral oils, which may not be readily appliable for these new liquids.
This seminar will first introduce the fundamental breakdown mechanisms of dielectric liquids. Dielectric breakdowns in transformer liquids can be broadly grouped into streamer initiation controlled breakdown and streamer propagation controlled breakdown. The former is dominating breakdowns under uniform field while the latter is dominating breakdowns under divergent field. Most of the previous breakdown studies have focused on either the uniform field or the divergent field. There is a lack of studies considering the moderately-uniform fields. Therefore, this seminar will then pay attention to the moderately-uniform fields and investigate the transition field factor boundary between the two breakdown mechanisms. Comparisons of impulse breakdown voltages between ester liquids and mineral oils are statistically analyzed and elaborated based on the breakdown mechanisms. A recent study on lightning impulse breakdown voltages of various transformer liquids using a large-scale winding coil electrode with and without paper wrapping are presented, which would provide reference to transformer insulation design using these new liquids.
Speaker
Professor Qiang Liu
Role: Professor of High Voltage Engineering
Organisation: The University of Manchester
Travel and Contact Information
Find event
Room 7011
Building 100
The University of Southampton
