As well known, the surface conditions of solid materials strongly affect flashover phenomena under high electric field. The artificial doping ingredients could change energy distribution and density electron hole traps. trapping parameters in layer have some influences on insulation strength. In order to adjust different parameters, composite epoxy resin intermingled with aluminum hydroxide are prepared. samples filler concentrations investigated through method measuring potential based...

Since the inception of research on hollow silica, use nanosilica (HNS) as additives in barrier materials has not been reported. In this study, we evaluated capacity HNS an additive modified polypropylene (MPP). According to X-ray diffraction (XRD), crystallinity, tensile strength, and thermal stability MPP/HNS nanocomposite containing 0.1[Formula: see text]phr approached maximum values. Moreover, had best performance terms water vapor oxygen resistance. The reasons for improvement were...

Optical phenomena accompanying the preflashover along a planar metal-alumina-metal structure were investigated under stepped AC voltage in vacuum. Two kinds of electrode contacts with and without sputtered gold films employed. For alumina, luminescence became observable at /spl sim/1 kV/sub peak/, revealed two stages depending on amplitude applied voltage. non-sputtered alumina optical emission appeared much higher presented irregular discrete light pulses. The energy band metal-alumina...

Ceramic material has been widely used as insulator in vacuum. Their high hardness and brittle property brings some difficulty the application. A new kind of machinable ceramic was invented recently. The can be machined easily accurately after being sintered, which provides possibility making with fine complicated configuration. paper studies its surface insulation performance flashover phenomena under pulsed excitation samples different crystallization parameters are tested vacuum level 10-4...

As well known, the surface conditions of solid materials strongly affect flashover phenomena under high electric field in vacuum. In this paper, laser treatment was used to scratch lines on alumina ceramic investigate influence sample surface. We found that after scratched by voltage changed obviously. Experimental results revealed how depth and density affected characteristic. The indicated while regulated suitably there showed a regular microstructure ceramic, vacuum shows best performance.

We report the flashover development phenomenon across a polished silicon wafer and its damage effect on surface under pulsed excitation of ∼0.4/2.5 µs with peak value >6 kV in atmospheric air. A visible light channel connecting two electrodes is observed before complete occurs. The filament pit–jut damages induced by are found surface. comprehensive hypothesis proposed according to which first filamentary current process occurs layer semiconductor then ionization air ambient above considered...

Furfural analysis has been proved a useful tool for the aging diagnosis of solid insulation in large oil-immersed power transformers. Up-to-now, diagnostic criteria operating transformers are urgent need. In investigation, quite lot data have collected, such as furfural concentrations, service durations, water contents, etc. To reveal relationship between contents oil and condition insulation, statistic analyses carried out. Then, factors affecting process duration is studied. Therefore,...

Semiconductor devices are being gradually applied in the fields of high-voltage and high-power technology, thus high-field characteristics semiconducting materials have been paid much attention. However, its development meets limitation surface discharge/flashover. Based on measurement voltage current waveforms optical observation, phenomena across silicon samples were preliminarily investigated under pulsed excitation atmosphere. Moreover, discharge behaviors compared with that insulating...

Ceramic material has been widely used as insulator in vacuum. Their high hardness and brittle property brings some difficulty the application. A new kind of machinable ceramic was invented recently. The can be machined easily accurately after being sintered, which provides possibility making with fine complicated configuration. However, insulating strength across surface is not known clearly. paper studies insulation performance flashover phenomena under pulsed excitation samples different...

Abstract Void is one of the critical issues affecting mechanical performance fiber-reinforced polymer composites. Aiming at composite parts formed by Liquid Composite Molding, this develops a sensor-aided injection strategy, including real-time online monitoring module and system, which realizes continuous detection resin flow automatic rate adjustment to minimize void content. Flow front profile continuously recorded in direction reconstructed real-time. It provides digital representation...

Electroluminescence (EL) phenomena from polymers has been investigated under 50Hz ac electrical stress. Because the light emission is very week, so we employ a sensitive photon counting module (PCM) and put sample into vacuum chamber to avoid influence of gases or impurities absorbed on surface sample. We use three kinds materials such as PTFE, LDPE, PP in this experiment. Their trap parameters are measured according theory isothermal relaxation current (IRC). By that method acquire energy...

Optical investigation of flashover phenomena across silicon is performed in vacuum. A pulse waveform ~0.4/2.5 mus employed as stimulation source. The p100-type wafers are the samples. images growing recorded by intensified charge couple device, and corresponding waveforms voltage current given. results primarily suggest that p-type begins with distortion electric field at edge anode. Injection minors may play an important role formation process filament current. It regarded plasma produced...

The extremely low frequency electric fields generated by time-harmonic dipole can be used for telecommunication, geophysical exploration and electromagnetic information of earthquake precursor. There are two main purposes the analytical solution with dipole. One is that field source described dipole, other arbitrary obtained superposing By means image method, general expression vertical embedded in second layer stratified conducting half-space derived. Firstly, boundary conditions, magnetic...

Partial admission can improve the thermal efficiency of steam turbines at low loads, but a non-uniform flow in circumference will be caused inevitably same time. That makes control stage blade subject to complex load, leading high cycle fatigue. Therefore, it is important calculate and accurately analyze transient response disk due partial admission. However, large number degrees freedom practical lead an extremely computational cost when finite element method used. A strategy for reducing...

Since the last decade, atmospheric pressure glow discharge (APGD) and dielectric barrier (DBD) has utilized for numerous applications. An experimental setup is constructed generating APGD or DBD. When inserting a mesh wire between electrode barrier, can be generated as form of The mechanisms DBD are discussed, their characteristics investigated compared by measuring electrical parameters optical emission. also employed to modify surface insulating materials. material, thickness barriers...

The surface conditions of solids strongly affect the related and interfacial phenomena, which implied difference between its bulk. In this paper, under pulsed excitation, pattern ingredient on two kinds semi-conductive material, silicon (Si) gallium arsenide (GaAs) were investigated based microcosmic analysis techniques, digital metallographic microscope (MM) scanning electron (SEM) prior to after flashover shots. At same time waveforms voltage, current light recorded for synthetically...

An online monitoring and diagnostic system for a 220 kV oil-immersed power transformer with 3 windings has been established in substation of China. The operation insulation condition evaluation were integrated into this system. Many sensors applied to monitor multiple items such as partial discharge, dissolved gas, moisture oil, oil temperature, coil hot spot iron core current, bushing so on. structure the was introduced flow, via information fusion technology, presented. Based on system, it...

Electroluminescence (EL) phenomena reveal some important information about the electrical ageing of solid insulating materials in discharge-free condition. The EL emission from surface several polymers with a planar electrode system was investigated under ac electric field vacuum. It observed at voltage as low /spl sim/1 kV. Its time-resolved distribution stepped voltages, intensity function ac, positive and negative half-rectified phase-resolved spectral distributions are studied detail....