Dresden 2026 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 31: Transport in Materials: Diffusion, Charge, or Heat Conduction II

MM 31.7: Talk

Thursday, March 12, 2026, 12:00–12:15, SCH/A216

Current-voltage curves of transformer oils: Analytical and numerical results — •Markus Bier — Technische Hochschule Würzburg-Schweinfurt, Schweinfurt, Germany

High-voltage transformers contain oil, which should allow for convective heat transport while sustaining electrical insulation. These oils are complex fluids composed of various molecular and colloidal species which, over time, give rise to the formation of charged entities due to numerous, by now not entirely known and fully understood mechanisms. A widely used technique to diagnose transformer oils are current-voltage curves, which can exhibit remarkable and non-trivial transient features upon polarisation of a relaxed oil or repolarisation of an electrically stressed oil. Theoretical modelling provides a bottom-up approach to link current-voltage curves to the underlying charge transport processes. The present contribution reports on analytical and numerical results obtained within theoretical investigations of reaction-drift-diffusion models based on Poisson-Nernst-Planck (PNP) theory. After presenting an analytical solution of the PNP equations for a semi-infinite system in the non-equilibrium steady state as well as analytical cross-over boundaries between different repolarisation regimes, the main features of numerical transient current-voltage curves for polarisation and repolarisation are discussed.

Reference: M. Bier, "Non-equilibrium steady states of electrolyte interfaces", New J. Phys. 26, 013008 (2024).

Keywords: Transformer oils; Complex fluids; Poisson-Nernst-Planck theory; Non-equilibrium steady states; Transient current-voltage curves