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Electric Arc Initiated Between Cables in Aeronautical Conditions : Characterization of the Impact on its Environment

par Laurence Laffont - publié le

Thomas VASQUEZ’ thesis defense intitled Caractérisation de l’Impact sur son Environnement d’un Arc Électrique Amorcé entre des Câbles en Conditions Aéronautiques (Electric Arc Initiated Between Cables in Aeronautical Conditions : Characterization of the Impact on its Environment ) Took place on Friday, June 25th 2021 at 10.00 am.

This work has been supervized by Philippe TEULET and Flavien VALENSI.

Jury :

P. TESTE, Laboratoire de Génie Électrique de Paris (GEEPS)

J.-M. BAUCHIRE, Laboratoire Groupe de Recherches sur l’Énergétique des Milieux Ionisés GREMI d’Orléans

David MALEC, LAboratoire PLAsma et Conversion d’Énergie de Toulouse

V. DEGARDIN, Institut d’Électronique, de Microélectronique et de Nanotechnologie

M. LISNYAK, Schneider Grenoble

R. CAUSSÉ, Airbus

A. RISACHER, IRT Saint Exupéry/ Safran

Philippe TEULET, LAboratoire PLAsma et Conversion d’Énergie de Toulouse (thesis supervisor)

FLAVIEN VALENSI, Laboratoire PLAsma et Conversion d’Énergie de Toulouse (thesis co-supervisor)

Abstract :

Arc faults occurring in electrical wiring systems or arc tracking phenomenon, are an issue known for decades in the aeronautic industry. The important quantity of energy released by the arcs may break the cables, as well as causing damages to the aircraft’s structure. Nowadays, environmental concerns lead to develop more efficient aircrafts. This is why the concept of a More Electric Aircraft (MEA) is being developed, and it is mainly aimed to define new electrical systems, in order to support the replacement of pneumatic and hydraulic systems by their electrical counterparts. This new concept is associated with an increasing electrical power, higher voltages, the use of direct current, and lighter material. These changes may affect the risk of arc tracking and its consequences ; this is why we need to study the impact of an arc occurring between electrical cables.

To do so, we realize a power balance of the arc in which we assess the mean power of the arc, the power transferred to the cables and causing their degradation, and the power in the arc column that is dissipated through conduction, convection and radiation. One of the main goals is to assess this power balance in several configurations of aircraft’s electrical wiring system : AC and DC, copper cables and aluminum cables, atmospheric pressure and altitude pressure (95 mbar). Arc tests are performed in a test chamber associated with a vacuum pump, allowing depressurization. With thermodynamic calculations and thanks to the power balance, we are able to obtain the mass of vaporized metal.

We use Optical Emission Spectroscopy (OES) to characterize the arc. We identify the emissive species of the plasma and we observe their temporal evolution. We associate these measurements with fast imaging coupled with spectral filters in order to obtain spatially and time-resolved data. OES measurements are also performed to obtain the overall temperature of the arc using Boltzmann plot method. We observe that the arc temperature is higher with aluminum cables than with copper cables, and the temperature is lower for both cables with the decreased pressure.

We realize an optical setup coupled with the fast camera in order to obtain the spatially-resolved arc temperature. This method is based on the intensity ratio of two emission lines of copper. Results are consistent with OES temperature measurements, and show spatial variation of the temperature, which emphasize the importance of erosion and cathode jet phenomenon.