Sökning: "electrical tree"
Visar resultat 1 - 5 av 82 avhandlingar innehållade orden electrical tree.
1. New Test Arrangement for Measuring Electrical Treeing in Polymers
Sammanfattning : Electrical treeing in high voltage cable insulation has been studied for a number of years and today the mostly used laboratory test set-up is the needle-plane electrode configuration. In this thesis a different type of electrode configuration is described. LÄS MER
2. Characterization of Electrical Insulation Exposed to Arbitrary Voltage Waveforms
Sammanfattning : The extensive use of power electronics in power systems today gives rise to other voltage waveforms than the conventional 50/60 Hz sinusoidal and consequently other types of electric stress act on high voltage insulating materials. Previous studies has shown that Pulse Width Modulated (PWM) voltages and similar waveforms increase stress in Adjustable Speed Drives (ASD) as compared with sinusoidal waveforms and it has also been shown that partial discharge (PD) activity is intensified during PWM voltages and that rise time of square like pulses affect PD inception voltage. LÄS MER
3. Voltage Stabilizers: From Design to Synthesis, Processing and Electrical Characterization
Sammanfattning : Voltage stabilizers are additives capable of inhibiting electrical treeing; a degradation mechanism for insulation materials subjected to strong divergent electric fields. The intended use is in cross-linked polyethylene (XLPE) high voltage power cable insulation where minute defects in the manufacturing process can give rise to the conditions needed for the initiation of treeing, which in the worst case scenario leads to failure of the insulation system with blackouts and expensive repairs as a consequence. LÄS MER
4. Characterising Resistance to Electrical Treeing in New XLPE-Based Materials for High-Voltage Cables
Sammanfattning : This work looks into electrical treeing in cross-linked polyethylene-based materials (XLPE), where the ability to resist tree development is considered as an indicator of improved applicability for insulation in high voltage power cables. The thesis presents results of a twin PhD project involving joint work of two students. LÄS MER
5. Polyethylene/metal oxide nanocomposites for electrical insulation in future HVDC-cables : probing properties from nano to macro
Sammanfattning : Nanocomposites of polyethylene and metal oxide nanoparticles have shown to be a feasible approachto the next generation of insulation in high voltage direct current cables. In order to reach an operationvoltage of 1 MV new insulation materials with reduced conductivity and increased breakdown strengthas compared to modern low-density polyethylene (LDPE) is needed. LÄS MER