Sökning: "electric breakdown"

Visar resultat 11 - 15 av 60 avhandlingar innehållade orden electric breakdown.

1. 11. Electrical Insulating Properties of Poly(Ethylene-co-Butyl Acrylate) Filled with Alumina Nanoparticles

   Författare :Nadejda Jäverberg; Hans Edin; John Fothergill; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; nanocomposites; poly ethylene-co-butyl acrylate ; EBA; alumina; dielectric permittivity; absorbed water; humidity; temperature; dielectric spectroscopy; breakdown strength; pre-breakdown current;

   Sammanfattning : In this work the electrical insulating properties of the nanocomposite materials based on poly(ethylene-co-butyl acrylate) filled with alumina nanoparticles are studied. The dielectric properties chosen for the evaluation are the dielectric permittivity and loss as well as the breakdown strength and the pre-breakdown currents. LÄS MER

3. 12. Charge Accumulation in Hybrid High Voltage Insulation

   Författare :Mats Sjöberg; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; dielectric barrier; charge accumulation; high voltage; dielectric barrier discharge; dielectric coating; hybrid insulation; electric field distribution; discharge modelling; breakdown strength; charge conditioning;

   Sammanfattning : This thesis deals with the novel idea of controlling the electric stress or field distribution in a hybrid air - solid-dielectric high voltage insulation by promoting accumulation of surface charges on the internal interfacial layers in the combined (hybrid) dielectric structure. Primarily, applications are expected to be found in high voltage dc systems and as a method to improve the resistance against insulation failure by overvoltages, e. LÄS MER

4. 13. Features of the Electric Fields Generated by Lightning with Special Attention to Positive Ground Flashes

   Författare :Dalina Johari; Vernon Cooray; Mahbubur Rahman; Fridolin Heidler; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; positive ground flashes; preliminary breakdown pulses; multiple-trains PBPs; positive leader; bidirectional leader; negative leader branch; subsequent return strokes; distant lightning; Engineering Science with specialization in Atmospheric Discharges; Teknisk fysik med inriktning mot atmosfäriska urladdningar;

   Sammanfattning : This thesis focuses on the main processes in positive ground flashes and the distant lightning environment for both positive and negative ground flashes. It presents the characteristics of the preliminary breakdown pulses (PBPs), the characteristics of the electric field pulses observed during leader propagation, and the characteristics of the electric fields produced by the first and the subsequent return strokes. LÄS MER

5. 14. Pre-breakdown Phenomena in Mineral Oil Based Nanofluids

   Författare :Mauricio Aljure; Marley Becerra Garcia; Øystein Leif Gurandsrud Hestad; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : Mineral oil is a dielectric liquid commonly used in high voltage equipment such as power transformers. Interestingly, it has been experimentally observed that the dielectric strength of the mineral oil is improved when nanoparticles are added. LÄS MER

7. 15. Fabrication and Characterization of Silicon Carbide Power Bipolar Junction Transistors

   Författare :Hyung-Seok Lee; Carl-Mikael Zetterling; Tat-Sing Chow; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; silicon carbide; power device; BJT; current gain; specific on resistance RSP_ON ; breakdown voltage; forward voltage drop; surface recombination; ohmic contact.; Electrical engineering; electronics and photonics; Elektroteknik; elektronik och fotonik;

   Sammanfattning : Silicon carbide bipolar junction transistors (BJTs) are attractive power switching devices because of the unique material properties of SiC with high breakdown electric field, high thermal conductivity and high saturated drift velocity of electrons. The SiC BJT has potential for very low specific on-resistances and this together with high temperature operation makes it very suitable for applications with high power densities. LÄS MER