Visar resultat 1 - 5 av 96 avhandlingar innehållade ordet corona.
Sammanfattning : Use of polymeric materials for high voltage outdoor insulation systems is increasing continuously. Insulating polymers gradually replace traditional materials like porcelain and glass and become dominant at ultra high voltages, e.g., in 1000 kV ac and 800 kV dc overhead power transmissions, which are presently being developed. LÄS MER
Sammanfattning : The heating of the solar corona has been investigated during four of decades and several mechanisms able to produce heating have been proposed. It has until now not been possible to produce quantitative estimates that would establish any of these heating mechanism as the most important in the solar corona. LÄS MER
3. Loss and recovery of hydrophobicity of polydimethylsiloxane after exposure to electrical discharges
Sammanfattning : Silicone rubber based on polydimethylsiloxane is used ashigh voltage outdoor insulation, due to its ability to preservethe hydrophobic surface properties during service and evenregain hydrophobicity after exposure to electrical discharges.The underlying processes for the hydrophobic recovery arediffusion of low molar mass siloxanes from the bulk to thesurface and reorientation by conformational changes ofmolecules in the surface region. LÄS MER
Sammanfattning : Microwave breakdown continues to be a risk in many applications involving the transmission and reception of microwave frequency signals. Satellite communication is especially interesting from the research point of view because of the extreme costs, and limited testing possibilities. LÄS MER
Sammanfattning : Electrical insulation can today be exposed to voltages having considerably higherfrequency components than the conventional power frequency AC 50 Hz or 60 Hz,for example due to the increased use of power electronics in power systems. Thishas in a number of cases caused unexpected behaviour, including failures. LÄS MER