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This paper provides a robust experimentalsimulation approach in predicting the partial discharge inception voltage (PDIV) for aeronautical applications. First, two polymers used as insulators in aeronautic components have been selected in this work, a polyimide and a polyetheretherketone. To study the electrical behavior of these materials, extensive dielectric spectroscopy measurements are carried out for different electric fields, temperatures and frequencies (E, T, and f). Then, a needleplane configuration is adopted for PDIV modeling using finiteelement method (FEM). As the model is strongly dependent upon the accurate estimation of the electric field, dielectric characterizations results are integrated in simulations to improve the precision of calculations. Thereafter, the PDIV can be estimated with the aid of Townsend's theory. Finally, a comparison between measured and computed PDIV values is presented and discussed.

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An experimental evidence of filamentary electrical conduction existence in polyimide (PI) films under DC voltage just prior to thermal breakdown is reported. This was achieved by real-time surface temperature mapping of PI-metallized samples initially at 300 °C using fast infrared thermography coupled to current-voltage measurements until the breakdown. The transition from a full-electrode conduction to a filamentary conduction is clearly identified through the detection of a localized hot spot within the PI samples in the last 100–150 ms before breakdown. A conduction path, with values inferior to 500 μm in the few ms before the breakdown, was estimated leading to temperature rising up to 100 K above the initial temperature. This work confirms the existence of a filamentary conduction in thermoset polymers prior thermal breakdown.