Sökning: "partial discharge"
Visar resultat 1 - 5 av 57 avhandlingar innehållade orden partial discharge.
1. Electrical Characterization of Partial Discharge Resistant Enamel Insulation
Sammanfattning : Adjustable speed drives for rotating machines have become increasingly popular as they provide possibilities of smooth and accurate process control as well as for energy savings. In such systems, due to the fact that the voltage applied at terminals of motor windings is no longer purely sinusoidal but characterized by a high content of harmonics, the appearing electrical and thermal stresses yield premature failures of the winding insulation, mainly because of an increased partial discharge (PD) activity. LÄS MER
2. Partial discharges studied by dielectric response method
Sammanfattning : The increasing demand of integrating various renewable energy recourses in power system requires extensive use of power electronic solutions, which allows energy conversion between different frequencies and stabilizes the system. Consequently, other than the traditional 50/60 Hz sinusoidal voltage stresses act on the high voltage insulation systems. LÄS MER
3. Partial Discharge Signatures of Defects in Insulation Systems Consisting of Oil and Oil-impregnated Paper
Sammanfattning : Partial discharge measurement is a common method for monitoring and diagnostics of power transformers, and can detect insulation malfunctions before they lead to failure. Different parameters extracted from the measured PD activity can be correlated to the PD source, and as a result it is possible to identify the PD source by analyzing the PD activity. LÄS MER
4. Dielectric Response and Partial Discharge Diagnostics of Insulation Systems by Utilizing High Voltage Impulses
Sammanfattning : In this thesis, power system transients are considered as an opportunity for development of on-line diagnostics of power components and specifically the insulation systems of power transformers and bushings.A new technique for on-line dielectric response measurement of power transformer bushings is proposed which utilizes natural transients in the power system, such as lightning and switching surges, as stimuli. LÄS MER
5. Partial Discharges at Repetitive Rapidly Changing Voltages
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