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Using several specially designed discharge chambers embodying point-point, point-plane and point-sphere electrode systems, and filled with dielectric liquid, a zone of low luminescent intensity was detected between the electrode corona and the point in the liquid at which the discharge channel originated. This dark zone is evidently the location of the mechanisms which are the critical precursors...
The results presented here refer to a tungsten point anode and stainless steel plane cathode. Figure 1 relates maximum positive streamer growth to pulse duration and pulse amplitude in nhexane. The figure shows a scatter in experimental points on the graph typical of such a set of curves. A smooth curve is drawn through each set of points, by eye, to approximate a best fit curve with a degree of uncertainty...
Studies were carried out for needle-plane gaps with a comparatively long separation in transformer oil. Relations between needle voltages and space charge quantities due to coronas by lightning impulse and AC voltages were obtained. It was found that the charge quantities for AC voltages were larger by 1.2 times and 6 times than that for the positive and the negative impulse voltages respectively...
Localized electrical discharges have been used to generate vapor bubbles in dielectric liquids, and the growth and collapse of these bubbles has been recorded photographically. The optical studies are based on a flash-illuminated shadowgraph apparatus. The expansion and collapse of a cavity in the low viscosity limit follows a simple hydrodynamic model and the predictions of the model are experimentally...
Measurements of the temporal variation of voltage and current in the spark discharge of liquid n-hexane were carried out. A dc-voltage, which increased linearly in time, was applied to a test cell with tip-plane electrode geometry. By careful mechanical design of the test cell a defined wave impedance of the whole experimental set-up was realized. A capacitive voltage divider was integrated into the...
A much refined experimental technique and analysis of measurements of dielectric breakdown in hydrocarbon liquids, in particular: n-hexane, has shown that the time lag distribution of an unperturbed liquid is governed by a Weibull probability function. Among dielectric liquids stressed at a constant electric field this is the first account of the applicability of the statistics of extreme values....
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