Recurrent-surge investigations

Fines, Ronald R (1956) Recurrent-surge investigations. PhD thesis, University of Glasgow.

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Abstract

This thesis concerns the design, construction and applications of two equipments, the Recurrent-Surge Oscillograph (R.S.O.), and the Recovery Voltage Indicator (R.V.I.) which rely on the recurrent injection of a suitable voltage or current waveform to an electrical network, and the oscillographic display of potentials across the whole or part of the network on a timebase synchronised to the injection waveform. The R.S.O. is particularly useful in determining the voltage distribution in windings, especially transformer windings, when subjected to rapid rates-of-rise of voltage such as occur on transmission lines under fault conditions, Whereas the natural phenomena are of considerable magnitude and occurring at random, the instrument described generates typical surge waveforms of low amplitude ( < 1000 volts) repetitively at fifty times per second, so that resulting stresses may be investigated at will and without fear of damage to the winding. The equipment may also be used as a high-speed oscillograph for the recording of repetitive transient phenomena, a special feature being the time resolution afforded, of the order of ten millimicroseconds, during the period immediately following timebase triggering. Tests may also be made to determine the characteristics (and certain faults to earth) of cables using reflected pulse techniques. The R.V.I. is used to inject a current repetitively, again at fifty times per second, into an electrical system which ideally may be a uniform transmission line, but in practice consists more often of an inter-connection of cables, reactors and transformers. The Injected current is of half-sine-wave form and represents the last half-cycle of line current (often a heavy fault current) before circuit breaker contacts open ideally, and the current ceases. Again the injected quantity is small (milllamperes) compared with the typical practical quantity (up to thousands of amperes), and the resultant recovery voltage across the circuit breaker contacts, which in the case of miniature simulation are represented by anode and cathode of a valve, is correspondingly small compared with the abnormally high potentials which may cause restriking of an arc between contacts in practice. These recovery voltages are due to the stored energy in the system at the time of rupture of current, and theoretical prediction of their severity is considered in various appendices. Part 1 of the thesis refers particularly to the R.S.O., and Part 2 to the R.V.I.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: F M Bruce
Keywords: Electromagnetics
Date of Award: 1956
Depositing User: Enlighten Team
Unique ID: glathesis:1956-73483
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56
URI: http://theses.gla.ac.uk/id/eprint/73483

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