Pre-breakdown conduction current pulses in insulating oils under non-uniform field conditions

Abstract

The pre-breakdown conduction current pulses in degassed transformer oil were studied using needle-sphere electrodes. The current pulses were recorded on a magnetic tape and then analysed using a pulse height analyser. The results showed that these current pulses were sensitive to the applied hydrostatic pressure as well as to the liquid temperature. With the needle positive the number of larger pulses reached a minimum at a pressure between 250 and 500 torr, while with the needle negative the pulse rate was greatest in this range of pressure. Increasing the temperature of the liquid or the applied voltage increased the pulse activity. When a needle-needle electrode system was used, pulse activity also showed a pronounced response to the applied hydrostatic pressure. It is suggested that a gaseous phase is involved in the breakdown process of liquids, which is most likely to be due to dissociation of the liquid molecules by energetic electrons.

General hypergeometric systems of equations and series of hypergeometric type

“…Also, the amplitudes and repetition rates of the conduction current bursts have been the subject of numerous statistical studies in recent years (Megahed and Nosseir 1969, Nosseir and Megahed 1970, Megahed and Tropper 1971, Nosseir 1973.…”

New observations of conduction current bursts in highly-stressed insulating liquids

“…Previous observations of conduction currents under direct voltages have usually been of their average values and their variations with voltage and with physical conditions (Singh et al 1972). Also, the amplitudes and repetition rates of the conduction current bursts have been the subject of numerous statistical studies in recent years (Megahed and Nosseir 1969, Nosseir and Megahed 1970, Megahed and Tropper 1971, Nosseir 1973.…”