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Prebreakdown current, photo current and conduction current are measured inn-hexane, cyclo-hexane, 1-hexene and benzene. Similar phenomena are observed in the saturated hydrocarbon liquids, n-hexane and cyclohexane, whereas great difference is observed in the unsaturated hydrocarbons, 1-hexene and benzene. In the case of bush-type light emission, the mean velocity is about 100 m/s, and the waveforms...
We show, in figs 1–5, how some typical current density characteristics are affected by variations in the model parameters. Although a direct comparison with experiment is not included in the present work the shape and magnitude of these curves agree closely with those obtained from experimental measurements on typical non-polar liquids [8]. Our choice of recombination coefficients is also broadly...
Series of experiments have shown that when liquid flows over the surface of solid body, both the liquid and the solid body become electrified, mainly because of friction. The quantity of charge and its polarity depends on mutual induction of the two bodies, also on their dielectrical previousness.
Steady state photocurrents observed on certain semiconducting electrodes of rather different properties depend on the square root of light intensity. This, together with the detailed Kinetics of the current transients, can be understood by assuming second order charge carrier recombination Kinetics to prevail within the solid phase.
Summarizing the more peculiar results of this work, we can point out that: i) Low-field physico-chemical properties of A and B types for M/DBT (and PXE) are in many respect remarkably different. ii) At AC high-voltages, it was shown that conduction in M/DBT is mainly due to an injection mechanisms.
An experimental investigation of electric field induced motion in transformer oil is reported. The oil was subjected to a voltage step giving fields of up to 5 MV /m. The observations are explained in terms of a model based on behavior of particles both at the oil/electrode interface and in the bulk of the oil. The results indicate that charged particles with diameters less than one micro-meter, rather...
The liquid crystal cholesteryl oleate (ChO) has been studied through the measured electric permittivity (ε′) and loss (ε″) over a vide range of temperature extending from its crystal phase to isotropic phase and at different spot frequencies in the range 1.25 to 200 MHz. The dipole moment, dielectric relaxation time and other related parameters have been evaluated and interpreted in terms of molecular...
The dielectric study of p-azoxy anisole and 1,1-diacetyl ferrocene liquid crystalline substances in dioxan solution at different concentrations and room temperature is reported. The dipole moment and the relaxation time are evaluated and a comparision of the dipole moment values is done with those calculated by using statical methods. The contributions of electronic polarizability, London dispersion...
Current instabilities in the farm of randomly occurring pulses are a problem encountered by all who endeavour to produce current-voltage characteristics of a liquid insulant. These pulses signal the impending electrical breakdown of the system unless precautions are taken. In addition to an intensive cleaning of the system and filtration of the liquid entering the test cell the usual procedure is...
These two new experiments bring us more information about the behaviour of liquid dielectrics. We intend to develop them by studying more liquids and by analysing more precisely the main characters affecting the partial discharges.
The electrical breakdown of liquid dielectrics involves the generation and growth of a vapor cavity [1,2] and the dynamics of these pre-breakdown cavities in low-viscosity fluids have been widely studied photographically through the use of pulsed schlieren and shadowgraph techniques. Hakim and Higham, Farazmand, and Chadband and Wright [31, were the first to publish schlieren photographs that optically...
Little concentrations of a hydrogen-bonding impurity as glycerol, tend to break the hydrogen bonded structure of pure water and to prevent crystallization. The properties obtained by extrapolation are certainly those of pure water: Tg is in good agreement with the glass transition temperature of vitreous ice; εs(T) shows the variations predicted by the model of RICE. Our results support the idea of...
(1) The states of water dissolved in DOP are classified into free water, cluster and hydrogen bonded water. (2) The water measured by Karl Fischer's method is free water. (3) The conduction in DOP is dependent on the free water i.e. primary and secondary free water. (4) The breakdown voltage depends on the amount of free water. The clusters work as the source of free water.
In spite of its lack of accuracy, the method presented gives a good idea of the thermalization distances of electrons created by photoionization of pure liquids; and allows discussion15 of the validity of the classical model of photoionization.
An experimental tool with a response time of milliseconds capable of indicating both the direction and magnitude of induced liquid motion within a stressed test gap has been developed. Observations are made at electrode surfaces with minimal disturbance. The basic principle of operation involves the use of an electrobalance to measure the force created by moving fluid at an electrode surface. The...
An experimental study on the combined γ-radiation and heat effects on the electrical properties of transformer oil is presented. Several samples of fresh unused transformer oil of the type used in Egypt is irradiated in a γ-cell for different time periods, at the same radiation conditions. Each sample, one at a time, is then raised to a different pre-specified temperature. At this temperature, we...
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