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dc.contributorDepartment of Electrical Engineeringen_US
dc.creatorWong, Ka-ming-
dc.identifier.urihttps://theses.lib.polyu.edu.hk/handle/200/1593-
dc.languageEnglishen_US
dc.publisherHong Kong Polytechnic University-
dc.rightsAll rights reserveden_US
dc.titleInvestigation of corona discharges and electrical breakdown in sulphur-hexafluoride/nitrogen mixturesen_US
dcterms.abstractThese days, corona was studied and investigated in different mixture ratio of SF6 and N2 by observing the pulse shape and frequency and the average current for a range of voltages from onset to breakdown. Models for the corona behaviour were developed and simulation programs written based on various proposed models for the ionisation and attachment parameters of gas mixtures. An important aspect was the use of the symmetrical point/cup electrode system introduced by MacAlpine, my supervisor whose symmetry allows the development of mathematical models not possible with the more traditional point/plane electrode system. A thorough understanding of the pre-breakdown (corona) phenomena is likely to lead to an explanation for the breakdown strength. The measurements were carried out over a range of pressures up to the commercially and industrially important 5-bar level. Both voltage polarities were studied. Experiments conducted in point-cup gaps can be considered to represent the geometric conditions in practical gas-insulated switchgear which are commonly used in power systems, where the breakdowns tend to originate with small metallic particles and the corona which develops at their pointed end. The mechanism of breakdown originating with a long metallic particle on the 'floor' of the earthed outer tube has some similarity with that of the point/plane system.en_US
dcterms.extentiii, 77 leaves : col. ill. ; 30 cmen_US
dcterms.isPartOfPolyU Electronic Thesesen_US
dcterms.issued2002en_US
dcterms.educationalLevelAll Masteren_US
dcterms.educationalLevelM.Phil.en_US
dcterms.LCSHHong Kong Polytechnic University -- Dissertationsen_US
dcterms.LCSHCorona (Electricity)en_US
dcterms.LCSHBreakdown (Electricity)en_US
dcterms.LCSHElectric insulators and insulation -- Sulphur-hexafluorideen_US
dcterms.accessRightsopen accessen_US

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