| This work concerns the techniques of non destructive testing used for the identification and the diagnosis of insulation systems in electrical engineering. These control methods are applied to polymeric composite materials. Indeed, these materials are insulating matrices of pure epoxy reinforced by particles, silicon carbide (SiC) and alumina (Al2O3).; The temporal spectroscopy is a method of diagnosis accessible industrially and making possible to identify the characteristics related to the total degradation of the insulations systems in electrical engineering (Hydro-generators, transformers, transport and distribution cables, polymers...) in a minimum time and constitutes one of the best technological choice among those available.; To apply this method, we developed a prototype which makes possible to read currents of polarization and depolarization based on the technique of superposition following the application of step voltage on samples of polymeric composite materials prepared in the laboratory. The results obtained are compared with frequency domain measurements which, although requiring a little more interpretation, can also provide information in real time.; All the experimental tests of this work confirm the dependence of the reinforcement size of grain on the dielectric constant. These tests were compared with some models existing in the literature which did not give a good agreement for the complex permittivity. The increase in conductivity above the threshold of percolation is mainly related to the increase of the number of grain-to-grain contact of reinforced particles.; Keywords: insulation system, particle reinforced composites, electrical conductivity, complex permittivity. |
