Pulsed Dielectric Breakdown of Solid Composite Epoxy Insulators

Solid dielectrics are desirable for improving the maintenance requirements, shelf life, power density, energy density, and manufacturing challenges associated with insulating high-voltage pulsed power systems. The ability to alter the dielectric properties of solid insulators by using nanoparticle additives is among their most attractive properties. By layering the type and/or fill percentage of nanoparticles, it is possible to spatially grade the dielectric permittivity between two locations. Achieving optimal dielectric properties through functional grading can significantly reduce electric field enhancements, enabling systems to be designed more compactly. Since solid dielectrics are not self-healing like liquid dielectrics, it is critical that they be well understood before being implemented. Epoxy dielectrics are of high interest because of their naturally high dielectric strength and their ability to fill complex geometries. In the work presented here, raw and composite epoxy dielectric samples are being studied under both low-voltage and pulsed high-voltage experimental conditions to characterize their dielectric properties. Specifically, the relative permittivity and breakdown strength of EPON 815C epoxy are evaluated with various loadings of alumina nanoparticles. The results demonstrate the ability to reliably alter the dielectric permittivity of the base epoxy material and that the dielectric strength is not significantly altered with loadings of alumina up to 5%. This implies that altered dielectrics using alumina nanoparticle additives may be used to optimize electric field profiles without negatively impacting dielectric strength.