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Propriétés diélectriques des gels isolants : application aux composants d'électronique de puissance

Abstract : This work provides a better understanding of the dielectric properties of the gels insulation in the particular context of its use in power electronics. Different measuring techniques which, for the most part have been developed in the characterization of insulating liquids (visualization streamers, optical detection of discharges, charge measuring apparent) were used. An optical method permitting partial discharge measurements under non-sinusoidal voltage (steep-fronted waves) has been developed. Discharges into cavities and ones attributed to the corona have been identified. A regime of reversible discharges and a regime of degradation where the properties of self-healing material are reduced were highlighted. The frequency of discharges increases with temperature. They could contribute to the acceleration of aging assembling in the long term. The partial discharge appears to be easier on impulse voltage in comparison to alternative. The visualization of phenomena generated by high field (generation and propagation of "streamers") allows to better characterize the mechanisms responsible for discharges. The conventional measures of partial discharges in alternative according to IEC are not relevant in the case of the characterisation of the gel under constraints impulse. A study of the breakdown of the silicone gel in various configurations electrode (sizes, shapes) as a function of temperature and the shape of the voltage waveform shows that depends on the electrode surface. The gel comes close much of a non-polar liquid than a solid.
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Submitted on : Tuesday, April 21, 2009 - 4:52:06 PM
Last modification on : Thursday, November 19, 2020 - 1:00:26 PM
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  • HAL Id : tel-00377405, version 1

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Minh Tuan Do. Propriétés diélectriques des gels isolants : application aux composants d'électronique de puissance. Sciences de l'ingénieur [physics]. Université Joseph-Fourier - Grenoble I, 2008. Français. ⟨tel-00377405⟩

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