Flashover Events Research Articles

Streak photography of the dynamic-electrical discharge behavior on insulator surfaces in vacuum

High-speed streak photography of surface breakdown or flashover events along the surface of monocrystalline quartz and polycrystalline alumina specimens is reported. The initiation of visible luminosity was observed to be a function of surface properties of the samples. It has been shown that light could originate independently at the anode as well as at the cathode, indicating that the initiation of surface flashover could start in any region. The propagation rate of luminosity, bridging the electrodes completely, was found to vary depending upon the location at which the light originated. The initiation of light at the cathode is discussed on the basis of an electron induced collision-ionization process and of radiative recombination of electrons in the conduction band with the empty or positively charged traps or defect centers. The emission of light at the anode end is discussed along the lines of a recombination process involving field ionized traps or defect centers and conduction electrons and of the hole-induced excitation of activator or defect centers by inelastic collision.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The Use Of A Zone Model In Fire Engineering Application

In this paper is shown the possibility to modernize fire protection engineering in a way that it will be on the same level as other parts of the design of a building. A fire simulation model will be presented shortly. The model predicts the time for smoke-logging, flash-over and detection events for a given geometry of the building. The input parameter is the fire growth curve. In a special section it is shown how the fire growth can be predicted. Sometimes the fire area is known, but more often statistical information has to be used. Finally some engineering applications are indicated, where the consequences of a fire in a bus garage and a textile factory are discussed.

Pulse Flashover of Solid Dielectrics in Vacuum

In an effort to understand the mechanisms which lead to changes in the surface flashover potential of insulators used in high power spark gaps a systematic study of the flashover potential of various organic insulators was undertaken. The flashover potential of these insulators was measured both before and after they had been exposed to the by-products of an arc from a surface discharge ignitor plug. These insulators were analyzed using Electron Spectroscopy for Chemical Analysis (ESCA) to determine what, if any, structural changes occurred on the surface of the insulator as a result of the flashover events and/or irradiation. A Scanning Electron Microscope (SEM) was also used to investigate the tracks formed on the insulators as the result of a surface flashover.