On the relation between current pulses and discharges

Effect of Additives on the Performance of Cable Oil and Kraft Paper Oil Composite

“…However, this trend changes above 14 kV, as the prebreakdown region approaches and most of the pulses in this region are larger in amplitude by several orders of magnitude. This phenomena is therefore similar to partial discharge activity reported in literature (Qureshi and Chadband 1988). formation of bubble on account of high current density at its sharp tip is the likely mechanism of pulse generation.…”

“…Their source of occurrence is not yet resolved and controversies continue, as some workers attribute them to suspended impurity particles (Wintenberg et al 1989, Buffman andBrignell 1979) whereas others consider either the gas bubbles as the reason (Zaky and Hawley 1973) or due to the initiation of partial discharge activity in oil (Qureshi and Chadband 1988). Fig 3 displays the behavior of pulse activity due to increasing stress level on the cathode point.…”

Electrical and transient atomization characteristics of a pulsed charge injection atomizer using electrically insulating liquids

“…However, the analysis was restricted to quiescent liquids and to single voltage steps. Qureshi (1992) examined the e↵ect of applying repeated voltage pulse trains in to dielectrics, however once more, the research was restricted to quiescent liquids, and in this case concentrated on discharge phenomena rather than maximizing the injected current. Furthermore, his experiments were not at frequencies and duty cycles typical of small engine applications.…”

“…It is sensible to assume that once the pulse width goes to a level smaller than relevant internal electrical timescales, such as ⌧ k , the output spray should behave di↵erently, and here this has been roughly observed. A reasonable explanation is that at pulse widths smaller than relevant electrical timescales, before the liquid emerges from the orifice, the dielectric has already been supplied with multiple HV pulses, therefore simulating a natural discharge process which injects charge in the form of pulses (Qureshi (1992)). While this is not of practical importance in engine applications, it has provided insight in to how such a device operates and has also verified that the timescales employed in calculations within this paper are applicable to charge injection atomizer operation and may be used to predict transient charge injection in computer simulations.…”