ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- All Subjects: Hydrophobicity
Description
All-dielectric self-supporting (ADSS) fiber optic cables are used for data transfer by the utilities. They are installed along high voltage transmission lines. Dry band arcing, a phenomenon which is observed in outdoor insulators, is also observed in ADSS cables. The heat developed during dry band arcing damages the ADSS cables' outer sheath. A method is presented here to rate the cable sheath using the power developed during dry band arcing. Because of the small diameter of ADSS cables, mechanical vibration is induced in ADSS cable. In order to avoid damage, vibration dampers known as spiral vibration dampers (SVD) are used over these ADSS cables. These dampers are installed near the armor rods, where the presence of leakage current and dry band activity is more. The effect of dampers on dry band activity is investigated by conducting experiments on ADSS cable and dampers. Observations made from the experiments suggest that the hydrophobicity of the cable and damper play a key role in stabilizing dry band arcs. Hydrophobic-ity of the samples have been compared. The importance of hydrophobicity of the samples is further illustrated with the help of simulation results. The results indi-cate that the electric field increases at the edges of water strip. The dry band arc-ing phenomenon could thus be correlated to the hydrophobicity of the outer sur-face of cable and damper.
ContributorsPrabakar, Kumaraguru (Author) / Karady, George G. (Thesis advisor) / Vittal, Vijay (Committee member) / Ayyanar, Raja (Committee member) / Arizona State University (Publisher)
Created2011
Description
Transmission voltages worldwide are increasing to accommodate higher power transfer from power generators to load centers. Insulator dimensions cannot increase linearly with the voltage, as supporting structures become too tall and heavy. Therefore, it is necessary to optimize the insulator design considering all operating conditions including dry, wet and contaminated. In order to design insulators suitably, a better understanding of the insulator flashover is required, as it is a serious issue regarding the safe operation of power systems. However, it is not always feasible to conduct field and laboratory studies due to limited time and money.
The desire to accurately predict the performance of insulator flashovers requires mathematical models. Dynamic models are more appropriate than static models in terms of the instantaneous variation of arc parameters. In this dissertation, a dynamic model including conditions for arc dynamics, arc re-ignition and arc motion with AC supply is first developed.
For an AC power source, it is important to consider the equivalent shunt capacitance in addition to the short circuit current when evaluating pollution test results. By including the power source in dynamic models, the effects of source parameters on the leakage current waveform, the voltage drop and the flashover voltage were systematically investigated. It has been observed that for the same insulator under the same pollution level, there is a large difference among these flashover performances in high voltage laboratories and real power systems. Source strength is believed to be responsible for this discrepancy. Investigations of test source strength were conducted in this work in order to study its impact on different types of insulators with a variety of geometries.
Traditional deterministic models which have been developed so far can only predict whether an insulator would flashover or withstand. In practice, insulator flashover is a statistical process, given that both pollution severity and flashover voltage are probabilistic variables. A probability approach to predict the insulator flashover likelihood is presented based on the newly developed dynamic model.
The desire to accurately predict the performance of insulator flashovers requires mathematical models. Dynamic models are more appropriate than static models in terms of the instantaneous variation of arc parameters. In this dissertation, a dynamic model including conditions for arc dynamics, arc re-ignition and arc motion with AC supply is first developed.
For an AC power source, it is important to consider the equivalent shunt capacitance in addition to the short circuit current when evaluating pollution test results. By including the power source in dynamic models, the effects of source parameters on the leakage current waveform, the voltage drop and the flashover voltage were systematically investigated. It has been observed that for the same insulator under the same pollution level, there is a large difference among these flashover performances in high voltage laboratories and real power systems. Source strength is believed to be responsible for this discrepancy. Investigations of test source strength were conducted in this work in order to study its impact on different types of insulators with a variety of geometries.
Traditional deterministic models which have been developed so far can only predict whether an insulator would flashover or withstand. In practice, insulator flashover is a statistical process, given that both pollution severity and flashover voltage are probabilistic variables. A probability approach to predict the insulator flashover likelihood is presented based on the newly developed dynamic model.
ContributorsHe, Li (Author) / Gorur, Ravi S (Thesis advisor) / Karady, George K (Committee member) / Ayyanar, Raja (Committee member) / Holbert, Keith E. (Committee member) / Arizona State University (Publisher)
Created2016