The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
From viewpoints of low environment impact, some kinds of environment-friendly insulating oils for power transformers have been developed. This paper deals with the discussion of charge behavior in these new oils by an electro-optic field measurement. Several potent insulating oils for power transformers have been proposed because of some excellent features not only on electrical but also chemical...
In this paper we use SF6 gas(GSF6) according to a surrounding temperature and are research to clarify the reason of GIS (Gas Insulated Switchgear) of the malfunction. The experiments of breakdown characteristics by temperature & pressure change of GSF6, and SF6 liquid (LSF6) in model GIS are described. From the experimentpsilas results, the breakdown characteristics 3-Pattern are classified the...
In this paper the investigation of breakdown characteristics liquefied SF6 (LSF6) in model GIS (gas insulated switchgear) were described. The ability of LSF6 insulation is higher than high-pressurized SF6 gas. The breakdown characteristics of LSF6 were produced by bubble formed evaporation of LSF6 and bubble caused by high electric emission and corona. Also, The property of dielectric breakdown is...
The main diffusion processes that are in devices for testing of transformer oil for gas chromatography are considered. The estimation of time for safety storage of most movable gas in transformer oil - hydrogen in several types of syringes is shown. It is obtained that the most suitable device is ldquoElchromrdquo, where used both glass frame of syringe and glass plunger. Besides it has PTFE sealing...
In recent years measurements of different Dielectric parameters in frequency domain is being employed for assessing the condition of the paper-oil insulation systems in Transformers. Understanding the variations in the patterns of the dielectric responses as a function of frequency of each of the dielectric media is important for judicious analysis & interpretation of the data for the realistic...
The propagation of point cathode-initiated streamers in cyclohexane with eight electronegative additives (electron scavengers) has been studied with fast impulses (<20 ns, <35 kV) applied to a 10 mm point-to-plane gap, using shadow graphic imaging and a differential charge-measurement technique. Due to a general random behavior of streamers, we could only separate effects from ldquostrongrdquo...
Even if the phenomenon of flow electrification has been observed for several decades, the physicochemical process appearing at the solid/liquid interface creating the double layer is not yet totally understood. In particular, returns from experiments (Cabaleiro, 2008) made with oil and pressboard seems to show that the wall current density at the interface for a diffuse layer under development is...
The paper presents the results of experiments on tribo-charging of a blend of mineral base oil and different zinc dialkylditophosphate (ZDDP) contents. Experiments were carried out on the specially built experimental facility to be a simplified model of an engine crankcase in whose interior an earthed metal shaft rotated at given angular velocities. The potential of a stiffening ring of a lip seal...
A complex analysis of the structure of electrohydrodynamic (EHD) flows in needle-plane electrode system is carried out on the basis of experimental data and results of computer simulation. An iterative algorithm for simulation of the bulk charge distribution is developed. Simulation is performed using the ANSYS system. The velocity and pressure fields and electrical characteristic of EHD-flows are...
The dielectric breakdown voltage of an insulating liquid is of importance as a measure of the liquidpsilas ability to withstand electric stress. The parameters of the standard test methods from different countries are not similar. In the different standards there are used five or six single breakdowns in a glass or a plastic vessel with about 0.5 litter test oil content. The voltage raising up velocities...
Gassing of oil is defined scientifically as the chemical decomposition of certain hydrocarbons, under the impact of electrical and thermal stress. Indeed, the homolytic breakdown of vulnerable covalent bonds generates both small and large free radicals. The small ones become gases dissolved in the oil, while the large fractions generate insoluble colloidal suspensions. Currently, the electrical power...
We have studied the spectral light from fast positive and negative streamers in five chlorocarbon liquids under pulsed divergent field conditions (30 kV). Atomic lines and C2 molecular Swan bands were observed, and with sufficient resolution to evaluate line and band-shapes. The characteristic broadening, shift and asymmetry of atomic lines varied significantly with the liquids, while differences...
A novel electrostatic precipitator CAROLAreg is developed for collection of fine oil mists. It operates on the principle of unipolar particle charging in the corona discharge and particle precipitation under the field of space charge. The pilot precipitator was tested at different gas temperatures. It is shown that the increase of gas temperature changes the characteristics of the corona discharge...
Highly biodegradable and renewable seed-based oils can be an alternative source of dielectric fluids to replace the non-friendly mineral oil-based dielectric fluids. However, the high moisture content of vegetable oils is not suitable for a viable dielectric fluid formulation for safe, economic and trouble free operation of power and distribution transformers. The reduction of the moisture level of...
We analyze the shear horizontal (SH) wave propagation through a viscous liquid loaded on a solid plate. Based on the analysis, the viscosity properties of liquid, liquid crystal, ionic liquid, and ionic liquid crystal are investigated. A SH wave device has a thin cell, in which we prepare a molecular orientation treatment and apply a voltage to molecules. Using the device, we measure the viscosity...
Insulating system of power transformers is mostly composed of two basic components: insulation oil and cellulose paper (oil-paper system). These components are of an organic nature and thatpsilas why they become very sensitive to operation degradation conditions (temperature, oxidation, moisture etc.). Aging of these components can endanger the failure free operation of the transformers. The main...
The acoustic phase change of a shear horizontal (SH) wave propagating into a nematic liquid crystal cell structure is measured under application of electric field. The numerical analyses are also performed by considering director distribution and viscosity distribution in the nematic liquid layer. The effective viscosity was calculated from the viscosity distribution profiles and the particle velocity...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.