Industry uses liquid dielectrics for a number of applications. For example, Mineral oil is used extensively inside electrical transformers as a fluid dielectric and to assist in cooling. Dielectric fluids with higher dielectric constants, such as electrical grade castor oil, are often used in high voltage capacitors to help prevent corona discharge and increase capacitance.
An invention at LLNL uses a mixture of solid and liquid dielectric media. This combination has properties that are an improvement over either separately. The solid phase, in the form of small pellets, inhibits fluid motion, which reduces leakage currents, while the liquid phase (dielectric oil) provides self-repair capabilities. Also, since the media is removable, the high voltage equipment can be serviced.
Provides higher performance while maintaining the functionality of a pure liquid dielectric.
This has the potential to replace any liquid dielectric media. It would be particularly attractive for high-power applications in the electric industry because it would increase energy efficiency and decrease waste heat.
Researchers have demonstrated and validated the technology using silicone oil and polyethylene beads, but other combinations solids and fluids are possible. U.S. Patent 8,749,951.