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In the current study we focus on dielectric properties (as a function of frequency and temperature) of a polymeric composite system composed of polyvinyl alcohol and barium titanate nano powder. In the investigations, the temperature range is between 50-295 K, and the frequency range is between 20 Hz--1 MHz. Polarization and conduction processes are investigated in the linear regime. Dielectric breakdown strengths of samples are also reported. The materials presented have potential to be implemented in cryogenic capacitor or field grading applications. Index Terms--Dielectric relaxation, composites, dielectric breakdown, nanodielectric.

High voltage testing of a three-phase 5-meter prototype high temperature superconducting (HTS) cable is discussed. Findings reveal an inception voltage in excess of the required 15.6 kVrms.

The electrical properties of semiconducting tapes used for field grading applications in high voltage technology are examined. Findings reveal that the tapes have U-shaped temperature dependence of resistivity corresponding to metallic and insulator type character for temperatures over and below 170 K.

Non-metallic structural materials that act as an electrical insulation are needed for cryogenic power applications. One of the extensively utilized materials is glass fiber reinforced resins (GFRR) and may also be known as GFRP and FRP. They are created from glass fiber cloth that are impregnated with an epoxy resin under pressure and heat. Although the materials based on GFRR have been employed extensively, reports about their dielectric properties at cryogenic temperatures and larger thicknesses are generally lacking in the literature. Therefore to guide electrical apparatus designers for cryogenic applications, GFRR samples with different thicknesses are tested in a liquid nitrogen bath. Scaling relation between the dielectric breakdown strength and the GFFR thickness is established. Their loss tangents are also reported at various frequencies. [ABSTRACT FROM AUTHOR]

In this paper we report the recent advances in nanodielectrics that were developed and tested for cryogenic dielectric applications. The systems studied are composed of nanometer size particles. Particles were produced using either an ex-situ or in-situ technique. It is observed that there are clear differences in the structural properties of materials produced using these two approaches. Either no significant degradation or improvement in the electrical insulation properties were observed for ex-situ nano-partide samples processed with an ultrasonic processor and in-situ nano-particle samples. Nanodielectrics have the potential to be tailored with better thermal and mechanical properties without losing their electrical insulation characteristics. [ABSTRACT FROM AUTHOR]