Thesis (Ph. D.)--Johns Hopkins University, 1928. / Cover title. Vita. "By J.B. Whitehead and R.H. Marvin." "Report to Engineering foundation of an experimental research conduceted in the Laboratory of electrical engineering of the Johns Hopkins university, Baltimore, MD." Bibliography: p. 15-16.

Thesis (Ph. D.)--John Hopkins University, 1931. / "By J.B. Whitehead and F. Hamburger, jr." Vita. "Presented at the summer convention of A.I.E.E., Asheville, N.C., June 22-26, 1931." Bibliography: p. 11.

Thesis (Ph. D.)--Columbia University, 1934. / Vita. Bibliography: p. 41-42.

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The present methods of ascertaining the probable sludging of transformer oils are laborious. A simple test, comparable to that used in obtaining the dielectric strength, would be of considerable value in reducing test manpower, equipment and expense. Present investigators measure such properties as oxygen absorption, colour change, increase in acidity, carbon dioxide evolved, water formed, the power factor, and the lnterfacial-tension value. Numerous dielectric materials exhibit anomalous dispersions. The attendant rise in dissipation factor encountered at the points of dispersion is helpful in determining the amounts and types of polarization present. Transformer oils, although initially non-polar, are subject to oxidation. This oxidation produces materials of polar molecular structure which govern the power loss in alternating current electric fields. The problem is one of correlating such losses to the state of the oil under test. This thesis deals with the investigations carried out on the above problem. Absorption bands for transformer oils have been found. The present work describes the presence and location of such absorption bands, and illustrates how the dipolar state of the oil affects the position of the loss peaks. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

No description available.

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in ful lment of the requirements for the degree of Master of Science in Engineering. June 2016 / It has been reported in literature that newly installed cable accessories can pass typical commissioning tests and yet show signi cant PD activity leading to premature failure in the long term. This research report details the partial discharge (PD) characterisation of three arti cial defects in MV cable terminations, at both power and very low frequency (VLF). The defects included a semi-conductor feather, a tram line in the cross-linked polyethylene (XLPE) insulation and an XLPE ring cut. The experimental methodology involved subjecting the terminations to a standard overvoltage withstand test, after which the PD activity was monitored, at 0.1 Hz and at 50 Hz excitation frequencies. All the defects passed the overvoltage test, despite some showing signi cant discharges. The defects gave distinct phase-resolved PD patterns that are e ectively invariant of excitation frequency. The PD magnitudes at power frequency were typically bigger than at VLF, while the PD inception voltages tended to be lower at VLF. The PD magnitudes of the semi-conductor feather defect surface discharges were found to increase with increasing applied voltage, while no increase was observed for the tram line and ring cut void discharges. The results show that common installation defects in MV cable terminations can be suitably characterised using VLF PD measurements / MT2016

No description available.

No description available.