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PhD position in study of the cut off in a “vacuum circuit breaker”

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Français - Anglais

Date Limite Candidature : jeudi 3 février 2022

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General information

Reference : UMR5213-STETRI-013
Workplace : TOULOUSE
Date of publication : Thursday, January 13, 2022
Scientific Responsible name : Pierre FRETON
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 April 2022
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

There are different types of disconnection technologies depending on the medium in which the arc develops. In the field of medium voltage (1 - 52 kV), we distinguish mainly between air, vacuum and SF6. From the point of view of environmental impact, vacuum technology is the best, especially compared to SF6, which is a greenhouse gas. In the "vacuum" technology, an arc is established in a plasma of metallic vapors coming from the electrodes (copper). The pressure is then of the order of a few 103 Pa. This arc can adopt two operating regimes: the diffuse regime and the concentrated regime (at high current intensities) where the arc is visually analogous to an electric arc created under atmospheric pressure. The application of an axial magnetic field (AMF) extends the current range in which the arc is in the diffuse mode. The mathematical representation of the behavior of such a medium is close to that of a two-temperature plasma and analogies exist. The objective of the thesis will be to set up, in a first step on a simplified geometry, a three-dimensional numerical model describing the plasma medium and to study the influence of the parameters (intensity, dimensions of the electrodes, value of the magnetic field, others parameters). Depending on the level of the intensity and thus of the current density, two regimes can exist: one subsonic (current density higher than 3000 kA/m2), the other supersonic. The current being alternating, both regimes will be studied and the model will have to be able to study the transition from one regime to the other. In a second step, once the model is developed and validated with the available experimental results, a real (more complex) geometry will be considered. Different shapes of electrodes will be studied as well as the movements of spacing and rotation of the electrodes. Although this cutting technology exists, very few works are present in the literature; however, the candidate will be able to rely on the expertise of the team and the industrial partner.

Work Context

This subject is part of a long-standing collaboration (more than 15 years) between the Siemens Company of Berlin and the LAPLACE laboratory. With the acquired experience [1-5] in the field of high voltage circuit breaker and the technological advances brought by the previous studies, the Siemens Energy Company and the LAPLACE laboratory now wish to progress in the field of vacuum switching.
[1] F. Reichert, J.J. Gonzalez and P. Freton, “Modelling and simulation of radiative energy transfer in high voltage circuit breaker”, J. Phys. D: Appl. Phys. 45 (2012) 375201 (11pp)
[2] J.J. Gonzalez, P. Freton, F. Reichert, D. Randrianarivao, “Turbulence and magnetic field calculations in high voltage circuit breakers, IEEE Transactions on Plasma Science, ID TPS5280.R1 (2012)
[3] J.J. Gonzalez, P. Freton, P. Reichert, A. Pechanka, “PTFE vapor contribution to pressure changes in high voltage circuit breakers” IEEE Transactions on Plasma Science, vol. 43, Issue: 8, (2015).
[4] A. Petchanka, F. Reichert, J.J. Gonzalez and P. Freton, “Modelling of deformation of PTFE nozzles in high voltage circuit breaker due to multiple interruptions”, J. Phys. D: Appl. Phys. 49 (2016) 135201
[5] F. Reichert, A. Petchanka, P. Freton and J.J. Gonzalez, “Studies on the Thermal Re-ignition in SF6 High-Voltage Circuit-Breakers by means of Coupled Simulation” Plasma Physics and Technology journal, vol 2, ISSN: 2336-2626 (2015)

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