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Results are presented for charging and reverse currents in spectral grade carbon tetrachloride, toluene and transformer oil. The decay of charging current with, time can be changed at first by exponential lair but after that as I∼ t−n where n = 0.33 for carbon tetrachloride and n = 0.5 for toluene. The voltage-current characteristics have been studied over a range of time interval from 0.3 sec to...
Past studies of the electrically modified forced flow through a cell with a wire two plate electrode geometry modelling the injection zone of an E.H.D. generator showed the existence of two flow regimes. We present here some more refined results based on velocity measurements by L.D.A‥ For both regimes, the velocity profiles allow us to explain how the injected space charge modifies the flow and how,...
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...
Using Kerr effect charge injection from point cathode and anode in nitrobenzene in prebreakdown electric field under pulse voltage of microsecond range has been recorded. Cathode emission started at Ei=0.5MV/cm and anode - at Ei=1.0MV/cm. Negative space charge was approximately uniformly distributed around the point cathode top, and anode positive charges injection was of local nature. Prebreakdown...
The Coulomb force appears appropriate for laboratory simulations of geophysical flows in spherical geometry. In particular the general atmospheric circulation may be modelled by injecting ions in an insulating liquid between non parallel electrodes (a spherical and a ellipsoidal one) thus generating a meridian flow in the absence of rotation. We study here the flow in the simple geometry of two planes...
The gas generation in a liquid is studied with a test arrangement simulating an all-film capacitor, a model previously developed. In the case of step voltages, the generation threshold voltage is obtained with good accuracy and low spread by recording bursts on the transient currents. These bursts are associated with the presence of streamers from which result gas generation. The presence of space...
An investigation has been made in order to develop a location technique of corona discharge in insulating oil, on behalf of the development of the UHV transformer. This paper describes the principle of analyzing the corona location by making use of electrostatic probes. The corona produces a space charge in the oil, and induces charges on the probes electrostatically. Thus, the location as well as...
Electric field distribution including space charge effect is calculated by the Charge Simulation Method. From the analysis of conduction current expression, the conduction current in liquids is found to be caused by Schottky emission affected by space charge. Experiments and simulations are performed with needle electrodes of various materials (W, Cu, Mo and Ni) with various tip radius (3, 6, 10,...
Extensive Kerr electro-optic field mapping and voltage/current measurements have been taken with highly purified water over the temperature range of T=0−30°C using parallel plane electrodes with average field strengths up to 160kV/cm. The Kerr constant of water B was measured to be B≃3.4 – 3.6×10−14m/V2 for free space light wavelength of 590nm and only slightly varies with temperature over the measurement...
We first described the equipment composed of two concentric cylindrical electrodes. The inner one is made of stainless steel and a special device has been perfected in order to have a film of fluid streaming down on this electrode. An electric field of several KV/cm is applied between this two electrodes. Then in the theoretical study the general equations for the space charge convected are established,...
The stationary current-voltage characteristics in a blade-plane set-up generally exhibit two main regimes of electrical conduction, a quasi-ohmic regime and one of rapid increase. The latter regime corresponds to dominance of charge injection by the blade associated with a vigourous liquid motion which contributes to the passage of the current. The theoretical study of bulk conduction in a wire-cylinder...
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