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.
Extensive high resolution electro-optic Kerr field mapping measurements have been taken with transformer oil near 20°c using parallel plane electrodes and field strengths near 0.2 MV/m. Static field measurements have been extended to the transient period following the application of a step voltage. Significant space charge effects resulting in electrode fields being enhanced by a factor of up to 2...
Since earlier work (1–4) had shown that polarity effects were important, the present study was designed to measure pressure effects under non-uniform field conditions using each polarity. Part of the study was conducted at high magnification to observe the streamer inception voltage under elevated pressures.
Experiments show that electric field promotes to form a vapor locking in a gap with a hot spot and in turn the formation of locked vapor produces the serious reduction of breakdown voltage. Especially it is argued that the dielectric strengh of liquid helium under serious hot spot conditions decreases below that for saturated gas.
1- The conduction current in oil under AC and positive DC voltages increases in general with increasing field strength or oil temperature. 2- When the oil is subject to positive DC voltage the leakage current is too much smaller than that with AC voltage. 3- The breakdown voltage of oil decreases as the oil quality decreases. 4- The breakdown voltage is lower for positive polarity then for negative...
The progressive improvement in the purification techniques of dielectric liquids renders the measurement of their resistivity more and more difficult, sometimes impossible (especially at room temperature) with conventional AC bridges (SCHERING bridge, transformer ratio bridge) they are not sensitive enough to detect losses (tanδ) or conductance G of a cell of capacitance C filled with a liquid of...
Liquid insulation occupies a key position in the range of electrical insulating materials. We can conceive of a volume of empty space to which matter is added, molecule by molecule, until the vacuum is transformed, in stages through low pressure gas, high pressure gas, liquid of low viscosity, liquid of high viscosity, to an amorphous solid. First assumptions might be that as the phase changes then...
The application of high electrical fields to a liquid dielectric induces internal pressures. These internal pressures have been the subject of numerous investigations [1–5].
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.
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...
Experimental relationships between pressure drop increase and heat transfer increase, as result of applying an electic field to forced convection heat transfer of oil in a circular tube, are presented as functions of current and applied voltage. A negative electric field results in more marked enhancement of heat transfer and pressure drop than a positive field at the same voltage. However, both heat...
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.