ETD Collection

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Has files: YesSubject: search.filters.subject.Corona (Electricity)

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    Relationship between corona power loss and audible noise
    (1997) Engelbrecht, Michael Sean
    Results are reported on an initial investigation into corona power loss and its relationship to corona initiated audible noise. The work has the goal of being able to accurately predict the corona power loss, from a transmission line, from knowledge of the audible noise on the line. Corona power loss and its relationship to corona current, applied voltage and electric field is also exarr-ined. Experiments were performed using two single phase, different diameter, corona cages. Although the corona cage test results showed no correlation between corona initiated broad band audible noise and corona power loss, a linear empirical relationship, with excellent correlation, was found to exist between corona power loss and 100Hz Hum (dBA above 20jlPa). Results showed that, at the same magnitude of electric field, within the l h o different diameter corona cages, the corona current is the same magnitude and the corona power loss is proportional to the applied voltage.
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    An investigation into methods of modelling positive inhomogeneous-field breakdown and discharge process in SF6 with emphasis on the corona stabilisation phenomenon
    (2016-07-20) Bhutt, Sanjeev
    Corona stabilisation is not a well understood phenomenon, consequently a rigorous theoretical description of how the merhanism operates does not exist. Furthermore, postulates on the prcJ'.tse physical processes that occur during corona stabilised breakdown are varied and conflicting. 1t was thus essential to develop a qualitative theory of how the mechanism operates around which a quantitative model could be constructed. To this aim, a detailed analysis of available modelling methods and empirical data from published works was carried out. This analysis together with additional finite elements modelling done as part of this work, leads to a proposed qualitative model which serves as a basis for a quantitative model developed to simulate corona stabilized breakdown from a fixed panicle defect. There is a favorable comparison between the predictions of the model and published measurements, thus imbuing optimism in the proposed method. The problem of measuring t: .;true charge deployed in a discharge is discussed and an experiment is designed to circumvent this problem.
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    Modelling of the propulsion mechanism for a miniaturized corona ionization thruster
    (2015-10-30) Krommenhoek, Marinus Frans
    In this dissertation a recipe has been outlined on how thrust can be calculated using the conservation of momentum in continuum form. With the aim of modelling a CORION (corona ionization) like thruster in mind it was then argued using a much simpler system and stochastic calculus why a statistical description of the system is necessary. From this the one-particle distribution emerged as a natural tool for the description of a system su cient for the determination of the system's thrust.This was followed by a short investigation into the background of non-equilibrium statistical mechanics, both classical and quantum, necessary to understand how one-particle distributions could be derived formally and in a physically consistent way. Mass ow and current-voltage experiments of the CORION like thrust system, necessary for characterization of part of the system, were conducted. This led to a proposal for a modelling strategy, consisting of merging di erent modelling approaches and descriptions considered throughout the dissertation.