The destruction or the reduction of performances of the insulating layers is very often at the origin of the observed failures in the components and systems. Insulation materials thus play a significant role in the reliability of electrical and electronic applications, where financial or personal safety issues are crucial, but also in large-scale distributed applications.

 

The GEM team is interested in understanding, in the short and long term, the dielectric phenomena that develop in materials under the effect of thermal, electrical and environmental stresses. Their study and analysis make it possible to increase the reliability through a choice of material and a suitable design of the component, the modelling of its aging and / or the development of new materials. The targeted applications are energy transport, embedded systems (aeronautics, automotive, space), high-performance equipment, sensors and any application incorporating insulating layers subjected to high electrical and thermal stresses.

 

The study and understanding of phenomena aimed at developing materials with high dielectric performance are the main objectives.

 

Solutions developed at GEM by S. Agnel, J. Castellon, J-C. Laurentie and P. Notingher ely on narrowly experimental and modelling approaches, using original methods that can be directly adapted to components and are implantable on site. It concerns in particular techniques called "with thermal stimulus", which the team develops and for which it enjoys strong international recognition. The current dynamic is related to the future high voltage power networks, necessary to transport high power over long distances ("super-grids") and whose main limiting factors are the materials for cables and equipment. Research is also focused on bio sourced and nanostructured materials for electrical engineering applications, as well as insulators used in electronic components.

 

Thanks to its strong links with materials engineering specialists, the team covers a wide range of aspects related to the development and aging of insulators. It has important means of dielectric studies, for some unparalleled at the French and world level.

 

PARTNERS : These works are carried out in collaboration with public partners (Universities of Toulouse, Poitiers, Poitiers, Paris, Bucharest, Bologna, Chengdu) and through close links with industrialists in the field (Nexans, General Electric, EDF, RTE, Hydro-Québec, SuperGrid Institute, ArianeGroup), in the context of bilateral or institutional projects.

 

cable. entree DIG

Insulation issue for power transmission cables and high-voltage circuit breakers

 

cable. entree DIG

Electrothermal aging tests on insulating materials

Space charge characterization bench using the thermal step method (TSM)

Space charge characterization bench using the thermal step method (TSM)

 

Test platform for the measurement of the internal electric field in HVDC 200-320 kV cables on the sites of Nexans (Calais) and General Electric (Stafford, UK) - Technology transfer

Example of space charge density evolution in the insulation of a power cable
subjected to 230 kV (63 kV/mm average applied electric field)

Example of space charge density evolution in the insulation of a power cable
subjected to 230 kV (63 kV/mm average applied electric field)